National Academies Press: OpenBook

Signal Timing Manual - Second Edition (2015)

Chapter: Chapter 8 - Implementation and Maintenance

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Suggested Citation:"Chapter 8 - Implementation and Maintenance ." National Academies of Sciences, Engineering, and Medicine. 2015. Signal Timing Manual - Second Edition. Washington, DC: The National Academies Press. doi: 10.17226/22097.
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Chapter 8. Implementaon and Maintenance CHAPTER 8 IMPLEMENTATION AND MAINTENANCE CONTENTS 8.1 TRANSFER PLANS FROM OFFICE TO FIELD .................................................................. 8-2 8.1.1 Finalize Timing Plans .............................................................................................................. 8-2 8.1.2 Create Timing Plan Mark-Ups or Electronic Files ....................................................... 8-3 8.1.3 Transfer Timing Plans to Local Controllers ................................................................... 8-5 8.2 FIELD OBSERVATIONS AND ADJUSTMENTS ................................................................ 8-5 8.2.1 Observe Trafic Operations at Individual Intersections............................................ 8-6 8.2.2 Drive Corridor and Observe Trafic Operations along the Corridor .................... 8-6 8.2.3 Make Adjustments .................................................................................................................... 8-6 8.2.4 Document Changes and Create As-Builts ........................................................................ 8-7 8.3 AFTER IMPLEMENTATION ................................................................................................. 8-7 8.3.1 Perform Before-and-After Study to Assess Desired Outcomes .............................. 8-7 8.3.2 Monitor the Signal System .................................................................................................... 8-9 8.3.3 Perform Maintenance Updates .......................................................................................... 8-18 8.4 STAFFING NEEDS ................................................................................................................. 8-20 8.4.1 Staff Positions ........................................................................................................................... 8-20 8.4.2 Staff Training ............................................................................................................................ 8-22 8.5 REFERENCES ......................................................................................................................... 8-22 Signal Timing Manual, Second Edion

Chapter 8. Implementaon and Maintenance LIST OF EXHIBITS Exhibit 8-1 Signal Timing Implementation and Maintenance Process .......................... 8-1 Exhibit 8-2 Signal Timing Plan Elements .................................................................................... 8-2 Exhibit 8-3 Signal Timing Transfer Using a Central System ............................................... 8-3 Exhibit 8-4 Signal Timing Transfer in the Field ....................................................................... 8-4 Exhibit 8-5 Signal Timing Transfer Using Hand-Entering ................................................... 8-4 Exhibit 8-6 Example of Signal Timing Plan Mark-Up ............................................................. 8-4 Exhibit 8-7 Field Work ....................................................................................................................... 8-5 Exhibit 8-8 Individual Intersection Observations ................................................................... 8-6 Exhibit 8-9 Potential Signal Timing Adjustments Based on Field Observations ................................................................................................................... 8-6 Exhibit 8-10 Example of Before-and-After Comparison: Time-Space Diagram ............ 8-8 Exhibit 8-11 Example of Before-and-After Comparison: Delay and Speed Graph .................................................................................................................................. 8-9 Exhibit 8-12 Example of Before-and-After Comparison: Percent Arrival on Green ............................................................................................................................... 8-10 Exhibit 8-13 Operational Monitoring Activities ...................................................................... 8-10 Exhibit 8-14 Example of PCD: Before Offset Adjustment .................................................... 8-12 Exhibit 8-15 Example of PCD: After Offset Adjustment ....................................................... 8-12 Exhibit 8-16 Potential Signal-Equipment-Related Issues .................................................... 8-13 Exhibit 8-17 Public Service Requests and Associated Signal Operations Considerations ............................................................................................................ 8-16 Signal Timing Manual, Second Edion

Chapter 8. Implementaon and Maintenance LIST OF EXHIBITS Exhibit 8-1 Signal Timing Implementation and Maintenance Process .......................... 8-1 Exhibit 8-2 Signal Timing Plan Elements .................................................................................... 8-2 Exhibit 8-3 Signal Timing Transfer Using a Central System ............................................... 8-3 Exhibit 8-4 Signal Timing Transfer in the Field ....................................................................... 8-4 Exhibit 8-5 Signal Timing Transfer Using Hand-Entering ................................................... 8-4 Exhibit 8-6 Example of Signal Timing Plan Mark-Up ............................................................. 8-4 Exhibit 8-7 Field Work ....................................................................................................................... 8-5 Exhibit 8-8 Individual Intersection Observations ................................................................... 8-6 Exhibit 8-9 Potential Signal Timing Adjustments Based on Field Observations ................................................................................................................... 8-6 Exhibit 8-10 Example of Before-and-After Comparison: Time-Space Diagram ............ 8-8 Exhibit 8-11 Example of Before-and-After Comparison: Delay and Speed Graph .................................................................................................................................. 8-9 Exhibit 8-12 Example of Before-and-After Comparison: Percent Arrival on Green ............................................................................................................................... 8-10 Exhibit 8-13 Operational Monitoring Activities ...................................................................... 8-10 Exhibit 8-14 Example of PCD: Before Offset Adjustment .................................................... 8-12 Exhibit 8-15 Example of PCD: After Offset Adjustment ....................................................... 8-12 Exhibit 8-16 Potential Signal-Equipment-Related Issues .................................................... 8-13 Exhibit 8-17 Public Service Requests and Associated Signal Operations Considerations ............................................................................................................ 8-16 Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-1 CHAPTER 8. IMPLEMENTATION AND MAINTENANCE This chapter summarizes activities required for effective signal timing implementation and maintenance. Exhibit 8-1 illustrates the process of taking inal timing plans (discussed throughout Chapters 5–7) through implementation and to the point where they must be monitored and maintained. Although initial implementation is important for the success of a signal timing project, maintenance ensures that the signal timing will continue to operate at the level expected by the operating agency and general public. Exhibit 8-1 Signal Timing Implementaon and Maintenance Process Signal Timing Manual, Second Edion

8-2 Chapter 8. Implementaon and Maintenance Before beginning the process shown in Exhibit 8-1, the practitioner should plan every step with future needs in mind. For example, in order to perform the before-and- after study in Step 8, a practitioner must collect the “before” data prior to implementing the timing plans in Step 3. A procedure should also be developed for saving existing timing plans. Not only will they serve as historical records, but they will also be a reference point if problems are observed after implementation. 8.1 TRANSFER PLANS FROM OFFICE TO FIELD After timing plans have been  inalized in the of ice, they must be transferred to controllers in the  ield. Various methods can be used for this transfer depending on the available communication (described in Chapter 4). If a central system has been connected to the  ield controllers,  inal plans can be transferred from the of ice; however, without communication between  ield controllers or a central system, timing plans must be installed at each location in the  ield either by hand or electronically. 8.1.1 Finalize Timing Plans Before implementation can begin, the practitioner should con irm that the elements outlined in Exhibit 8-2 have been de ined and approved by the operating agency as part of the signal timing development process. Timing Plan Category Timing Plan Element Reference Objecves Operang Agency Objecves 3.4 Operaonal Objecves and Performance Measures General Parameters Time-of-Day Schedules 6.3 Time-of-Day Plans Phase Numbering 5.1.1 Movement and Phase Numbering Phase Sequence 5.1.2 Ring-and-Barrier Concept 5.1.3 Leƒ-Turn Phasing 7.2.6 Bandwidth 7.6.1 Phase Sequence Overlaps 5.1.4 Overlaps Detector Assignments 5.1.5 Detector Assignments Detector Configuraons 6.2 Detector Configuraons 7.5.2 Actuang the Coordinated Phase Load Switch Assignments 5.1.6 Load Switch Assignments Uncoordinated Parameters Yellow Change 6.1.1 Yellow Change Red Clearance 6.1.2 Red Clearance Minimum Green 6.1.3 Minimum Green Maximum Green 6.1.4 Maximum Green Passage Time 6.1.5 Passage Time (Unit Extension or Gap Time) Minimum Gap 6.1.5 Passage Time (Unit Extension or Gap Time) Time Before Reducon 6.1.5 Passage Time (Unit Extension or Gap Time) Time to Reduce 6.1.5 Passage Time (Unit Extension or Gap Time) Walk Interval 6.1.6 Pedestrian Intervals 7.5.1 Pedestrian Timing and Walk Modes Flashing Don’t Walk Interval 6.1.6 Pedestrian Intervals 7.5.1 Pedestrian Timing and Walk Modes Dual Entry 6.1.7 Dual Entry Recalls 6.1.8 Recalls and Memory Modes Memory Modes 6.1.8 Recalls and Memory Modes Exhibit 8-2 Signal Timing Plan Elements Signal Timing Manual, Second Edi­on

8-2 Chapter 8. Implementaon and Maintenance Before beginning the process shown in Exhibit 8-1, the practitioner should plan every step with future needs in mind. For example, in order to perform the before-and- after study in Step 8, a practitioner must collect the “before” data prior to implementing the timing plans in Step 3. A procedure should also be developed for saving existing timing plans. Not only will they serve as historical records, but they will also be a reference point if problems are observed after implementation. 8.1 TRANSFER PLANS FROM OFFICE TO FIELD After timing plans have been  inalized in the of ice, they must be transferred to controllers in the  ield. Various methods can be used for this transfer depending on the available communication (described in Chapter 4). If a central system has been connected to the  ield controllers,  inal plans can be transferred from the of ice; however, without communication between  ield controllers or a central system, timing plans must be installed at each location in the  ield either by hand or electronically. 8.1.1 Finalize Timing Plans Before implementation can begin, the practitioner should con irm that the elements outlined in Exhibit 8-2 have been de ined and approved by the operating agency as part of the signal timing development process. Timing Plan Category Timing Plan Element Reference Objecves Operang Agency Objecves 3.4 Operaonal Objecves and Performance Measures General Parameters Time-of-Day Schedules 6.3 Time-of-Day Plans Phase Numbering 5.1.1 Movement and Phase Numbering Phase Sequence 5.1.2 Ring-and-Barrier Concept 5.1.3 Leƒ-Turn Phasing 7.2.6 Bandwidth 7.6.1 Phase Sequence Overlaps 5.1.4 Overlaps Detector Assignments 5.1.5 Detector Assignments Detector Configuraons 6.2 Detector Configuraons 7.5.2 Actuang the Coordinated Phase Load Switch Assignments 5.1.6 Load Switch Assignments Uncoordinated Parameters Yellow Change 6.1.1 Yellow Change Red Clearance 6.1.2 Red Clearance Minimum Green 6.1.3 Minimum Green Maximum Green 6.1.4 Maximum Green Passage Time 6.1.5 Passage Time (Unit Extension or Gap Time) Minimum Gap 6.1.5 Passage Time (Unit Extension or Gap Time) Time Before Reducon 6.1.5 Passage Time (Unit Extension or Gap Time) Time to Reduce 6.1.5 Passage Time (Unit Extension or Gap Time) Walk Interval 6.1.6 Pedestrian Intervals 7.5.1 Pedestrian Timing and Walk Modes Flashing Don’t Walk Interval 6.1.6 Pedestrian Intervals 7.5.1 Pedestrian Timing and Walk Modes Dual Entry 6.1.7 Dual Entry Recalls 6.1.8 Recalls and Memory Modes Memory Modes 6.1.8 Recalls and Memory Modes Exhibit 8-2 Signal Timing Plan Elements Signal Timing Manual, Second Edi­on Chapter 8. Implementaon and Maintenance 8-3 Timing Plan Category Timing Plan Element Reference Coordinated Parameters Coordinated Phases 7.3.1 Coordinated Phases 7.4.1 Coordinated Phases Guidance Cycle Length 7.3.2 Cycle Length 7.4.2 Cycle Length Guidance Splits 7.3.3 Splits 7.4.3 Splits Guidance Force-Offs 7.3.4 Force-Offs 7.4.4 Force-Offs Guidance Permissives 7.3.5 Permissives 7.4.5 Permissives Guidance Yield Point 7.3.6 Yield Point 7.4.6 Yield Point Guidance Paern Sync Reference 7.3.7 Pa ern Sync Reference 7.4.7 Pa ern Sync Reference Guidance Offset Reference Point 7.3.8 Offset Reference Point 7.4.8 Offset Reference Point Guidance Offsets 7.3.9 Offsets 7.4.9 Offsets Guidance Walk Modes 7.5.1 Pedestrian Timing and Walk Modes Transion Modes 7.5.3 Transiˆon Logic 8.1.2 Create Timing Plan Mark-Ups or Electronic Files As mentioned previously, there are three basic methods for transferring inal timing plans from the ofice to controllers in the ield: 1. Use of a central system (as shown in Exhibit 8-3), 2. Electronic transfer in the ield (as shown in Exhibit 8-4), and 3. Hand-entering values (as shown in Exhibit 8-5). If a practitioner plans to use a central system or transfer timing plans electronically in the ield, electronic iles of the timing plans must be produced. A detailed review of each electronic ile should be performed before sending the inal iles to the controllers. This will minimize the number of data entry errors and allow for adequate preparation prior to ield implementation. If yellow and/or red settings are being altered or if phasing is being revised, a formal approval by the operating agency’s trafic signal engineer may be required before the changes can be implemented. Exhibit 8-3 Signal Timing Transfer Using a Central System Signal Timing Manual, Second Edion

8-4 Chapter 8. Implementaon and Maintenance If a practitioner plans to hand-enter values, an easy way to ensure that all of the required signal timing changes are incorporated in the ield is to mark-up existing timing sheets by hand, as shown in Exhibit 8-6. Hand-entering values is not the preferred method for signal timing implementation because it increases the potential for errors, but it can be a useful approach when the operating agency does not have the ability to download timing plans electronically. Taking marked-up timing plans to the ield will reduce the time required to hand-enter all of the values. Once the draft controller mark-ups are complete, a detailed review of this information should be performed to ensure that the correct timings have been transcribed. Additionally, this review can serve as quality assurance, revealing any parameters that might need to be modiied in order for the new timing plans to operate correctly. Exhibit 8-4 Signal Timing Transfer in the Field Exhibit 8-5 Signal Timing Transfer Using Hand-Entering Exhibit 8-6 Example of Signal Timing Plan Mark-Up Signal Timing Manual, Second Edion

8-4 Chapter 8. Implementaon and Maintenance If a practitioner plans to hand-enter values, an easy way to ensure that all of the required signal timing changes are incorporated in the ield is to mark-up existing timing sheets by hand, as shown in Exhibit 8-6. Hand-entering values is not the preferred method for signal timing implementation because it increases the potential for errors, but it can be a useful approach when the operating agency does not have the ability to download timing plans electronically. Taking marked-up timing plans to the ield will reduce the time required to hand-enter all of the values. Once the draft controller mark-ups are complete, a detailed review of this information should be performed to ensure that the correct timings have been transcribed. Additionally, this review can serve as quality assurance, revealing any parameters that might need to be modiied in order for the new timing plans to operate correctly. Exhibit 8-4 Signal Timing Transfer in the Field Exhibit 8-5 Signal Timing Transfer Using Hand-Entering Exhibit 8-6 Example of Signal Timing Plan Mark-Up Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-5 8.1.3 Transfer Timing Plans to Local Controllers As explained previously, this step depends on the type of communication that is available. Before making any changes, the practitioner should save all existing timing plans in case the new timing plans have unacceptable results. If there is a central system or master controller with communications in place (as illustrated in Exhibit 8-3), the signal timing software will be capable of transferring the signal timing plans directly to each controller. While manual ine-tuning in the ield may be required as part of ield implementation, manual inputs will be signiicantly reduced with a central system. On the other hand, if there is no central system or master controller with communications, the practitioner will need to transfer the timing plans in the ield at each individual controller, which can be done electronically (as illustrated in Exhibit 8-4) or manually (as illustrated in Exhibit 8-5). While electronic transfers still take time (because each timing plan must be uploaded individually), this method reduces the potential for human error. Regardless of the method used to transfer the timing plans, the practitioner should verify that the values were successfully uploaded at each controller. 8.2 FIELD OBSERVATIONS AND ADJUSTMENTS Field implementation (Exhibit 8-7 is practitioner observing real-time operation) is the most critical part of the signal timing process. Both science and inesse are needed to fully realize a good timing plan in the ield because of potential site-speciic conditions. However, care should be taken not to draw erroneous conclusions from a snapshot of time. Cycle-by-cycle variations will occur, and the practitioner must be patient during observations. A simple and effective means of observation is periodically driving the corridor at different times of day. For example, some staff can be assigned corridors to observe on their way to and from work. Depending on the history of the corridor and the number of proposed timing plans, ield implementation and observations should span a minimum of three days (two days during weekday operations and one day during weekend operations). If feasible, observing trafic operations simultaneously in the ield and via trafic management center (TMC) cameras can provide an eficient way to identify problem areas along a corridor (resulting from short split times, excessive queuing, phase failures, and/or hardware issues). The following section provides guidance on ield observations and associated signal timing adjustments. To assist with field implementaon, a field notebook should be generated that includes hard copies of the exisng and proposed signal ming plans, me- space diagrams, traffic volumes, and a method for nong changes in the field. Exhibit 8-7 Field Work Signal Timing Manual, Second Edi‡on

8-6 Chapter 8. Implementaon and Maintenance 8.2.1 Observe Traffic Operaons at Individual Intersecons A practitioner should start ield observations at individual intersections, ensuring that the timing plans were transferred correctly at each location. There are some signal timing parameters that will be easy to check by timing operations at the intersection, while other parameters will simply need to be veriied through observation (as summarized in Exhibit 8-8). In particular, it will be important for the practitioner to determine whether the cycle length and green time distributions are appropriate for the trafic demand. Timed Parameters Observed Parameters □ Yellow change □ Red clearance □ Minimum green □ Cycle length □ Walk interval □ Flashing don’t walk interval □ Phase sequence □ Overlaps □ Minor street delay □ Major street le€-turn delay □ Vehicle queuing 8.2.2 Drive Corridor and Observe Traffic Operaons along the Corridor The signalized intersections that are part of the ield implementation may be operating independently, which would not require a review of the corridor operations. However, if the signal system is coordinated, the practitioner should drive the corridor after observing operations at each individual intersection. A review of vehicle progression can help determine whether changes to the offsets or left-turn phase sequence are necessary. 8.2.3 Make Adjustments If the practitioner observes opportunities for improvement at individual intersections or along the corridor, he or she can make adjustments in the ield. Cycle- by-cycle variations can occur, so the practitioner should ensure that changes are made based on observations of a cross-section of conditions. Exhibit 8-9 provides a summary of some potential adjustments that may improve operations. Because changes can have a domino effect, the practitioner should be aware of how adjustments may inluence other movements or intersections. Most importantly, the practitioner should keep the operating agency’s objectives in mind when making any adjustments in the ield. Field Observation Potential Adjustments Long minor street delay □ Redistribute green me between major street phases and minor street phases (e.g., minimum green, maximum green, or splits). □ Review cycle length. □ Review passage se‰ngs for major street phases. □ Consider actuang the coordinated phase(s). Long major street le€- turn delay □ Redistribute green me to major street le€-turn phases (e.g., minimum green, maximum green, or splits). □ Review passage se‰ngs for major street through phases and minor street phases. □ Consider le€-turn phase sequence. Exhibit 8-8 Individual Intersecon Observaons Exhibit 8-9 Potenal Signal Timing Adjustments Based on Field Observaons Signal Timing Manual, Second Edion

8-6 Chapter 8. Implementaon and Maintenance 8.2.1 Observe Traffic Operaons at Individual Intersecons A practitioner should start ield observations at individual intersections, ensuring that the timing plans were transferred correctly at each location. There are some signal timing parameters that will be easy to check by timing operations at the intersection, while other parameters will simply need to be veriied through observation (as summarized in Exhibit 8-8). In particular, it will be important for the practitioner to determine whether the cycle length and green time distributions are appropriate for the trafic demand. Timed Parameters Observed Parameters □ Yellow change □ Red clearance □ Minimum green □ Cycle length □ Walk interval □ Flashing don’t walk interval □ Phase sequence □ Overlaps □ Minor street delay □ Major street le€-turn delay □ Vehicle queuing 8.2.2 Drive Corridor and Observe Traffic Operaons along the Corridor The signalized intersections that are part of the ield implementation may be operating independently, which would not require a review of the corridor operations. However, if the signal system is coordinated, the practitioner should drive the corridor after observing operations at each individual intersection. A review of vehicle progression can help determine whether changes to the offsets or left-turn phase sequence are necessary. 8.2.3 Make Adjustments If the practitioner observes opportunities for improvement at individual intersections or along the corridor, he or she can make adjustments in the ield. Cycle- by-cycle variations can occur, so the practitioner should ensure that changes are made based on observations of a cross-section of conditions. Exhibit 8-9 provides a summary of some potential adjustments that may improve operations. Because changes can have a domino effect, the practitioner should be aware of how adjustments may inluence other movements or intersections. Most importantly, the practitioner should keep the operating agency’s objectives in mind when making any adjustments in the ield. Field Observation Potential Adjustments Long minor street delay □ Redistribute green me between major street phases and minor street phases (e.g., minimum green, maximum green, or splits). □ Review cycle length. □ Review passage se‰ngs for major street phases. □ Consider actuang the coordinated phase(s). Long major street le€- turn delay □ Redistribute green me to major street le€-turn phases (e.g., minimum green, maximum green, or splits). □ Review passage se‰ngs for major street through phases and minor street phases. □ Consider le€-turn phase sequence. Exhibit 8-8 Individual Intersecon Observaons Exhibit 8-9 Potenal Signal Timing Adjustments Based on Field Observaons Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-7 Field Observation Potential Adjustments Vehicle queuing □ Redistribute green me to phases with queuing (e.g., minimum green, maximum green, or splits). □ Review cycle length. □ Review offsets. □ Review passage se­ngs for other phases (not experiencing queuing). □ Consider le‚-turn phase sequence. □ Consider phase re-service. Vehicle platoons arriving on red □ Review offsets. □ Consider le‚-turn phase sequence. □ Review cycle length. □ Review upstream intersecons for early return to green and possible offset adjustment. 8.2.4 Document Changes and Create As-Builts Documenting the signal timing plans that were ultimately implemented in the ield is important to the long-term success of a signal system. Changes should be documented in three places: • On Paper. Any changes that are made in the ield should be documented in both a ield notebook that will be taken back to the of ice and in the cabinet notebook kept at each intersection. • Electronically. All electronic iles saved to the central computer should be updated at the end of ield implementation to re lect the latest timing plans. If a central system and communication exist, the timing plans can be transferred from the ield controllers to the central system. In the absence of a central system, a practitioner may want to use a laptop (if available) to transfer timing plans from intersections with changes. However, it may be more ef icient to record changes in the ield notebook and update the electronic iles by hand once back at the of ice. • In Software Models. In order to simplify future maintenance efforts, the practitioner should also update any software used to develop signal timing. If changes in traf ic require the operating agency to reconsider operations in the future, a model of inal timing values will be ready. Such model networks may also be useful for before-and-after studies, as discussed in the next section. 8.3 AFTER IMPLEMENTATION After ield implementation is complete, there are usually two outstanding items: (1) a before-and-after study (if desired or required) and (2) ongoing monitoring and maintenance. Before-and-after studies are optional, but they can help an operating agency evaluate signal timing objectives and document system performance. Monitoring and maintenance are activities that will continue throughout the life of the signal and are necessary for keeping the signal operating in a manner that is acceptable to the public and the operating agency. 8.3.1 Perform Before-and-A­er Study to Assess Desired Outcomes While before-and-after studies are a traditional means of assessment, they take into account a very small sample of operations. Newer techniques of operational monitoring (See Section 8.3.2.1) are beginning to replace more traditional data collection and Signal Timing Manual, Second Edi„on

8-8 Chapter 8. Implementaon and Maintenance analysis, such as before-and-after studies, which are often more expensive to perform and more limited in their assessment. Before-and-after studies commonly compare travel time, delay, and queuing, but an operating agency’s objectives should be reviewed when choosing which performance measures to evaluate. While before-and-after studies may incorporate some information from software models, the most valuable information will come from the ield. For example, travel time and delay are often evaluated using loating cars that drive the corridor, typically while using a GPS device that records distance and time. Time-space diagrams (introduced in Chapter 7) are often used to illustrate the before-and-after effects of signal timing plans, speciically those related to travel time, delay, and speed. A time-space diagram can highlight the locations on the corridor where users experience stops and long delays (as shown in Exhibit 8-10). Overall, this example shows that progression along the corridor improved after the new signal timing plans were implemented; the time to travel the entire corridor decreased. Graphs of performance measures can also help a practitioner identify changes that resulted from new signal timing plans. Exhibit 8-11 illustrates delay and speeds experienced at speciic intersections along a corridor. This example shows that speeds increased after implementation of new signal timing plans, and delay was distributed more evenly across the corridor, with most locations experiencing a decrease. A before-and-after study report is an opportunity to conirm that the objectives of a retiming effort were met. Some agencies use this step in the process to inform elected leaders about the success of a project and to document future opportunities. It may be posted on the agency website and/or passed along to news agencies for the public to view. The after study is also a benchmark for use in ongoing monitoring of the system and can be used as a basis to determine retiming needs. Exhibit 8-10 Example of Before-and-Aer Comparison: Time- Space Diagram When developing a project, it is important to determine the type of before-and-aer report that will be needed. Signal Timing Manual, Second Edion

8-8 Chapter 8. Implementaon and Maintenance analysis, such as before-and-after studies, which are often more expensive to perform and more limited in their assessment. Before-and-after studies commonly compare travel time, delay, and queuing, but an operating agency’s objectives should be reviewed when choosing which performance measures to evaluate. While before-and-after studies may incorporate some information from software models, the most valuable information will come from the ield. For example, travel time and delay are often evaluated using loating cars that drive the corridor, typically while using a GPS device that records distance and time. Time-space diagrams (introduced in Chapter 7) are often used to illustrate the before-and-after effects of signal timing plans, speciically those related to travel time, delay, and speed. A time-space diagram can highlight the locations on the corridor where users experience stops and long delays (as shown in Exhibit 8-10). Overall, this example shows that progression along the corridor improved after the new signal timing plans were implemented; the time to travel the entire corridor decreased. Graphs of performance measures can also help a practitioner identify changes that resulted from new signal timing plans. Exhibit 8-11 illustrates delay and speeds experienced at speciic intersections along a corridor. This example shows that speeds increased after implementation of new signal timing plans, and delay was distributed more evenly across the corridor, with most locations experiencing a decrease. A before-and-after study report is an opportunity to conirm that the objectives of a retiming effort were met. Some agencies use this step in the process to inform elected leaders about the success of a project and to document future opportunities. It may be posted on the agency website and/or passed along to news agencies for the public to view. The after study is also a benchmark for use in ongoing monitoring of the system and can be used as a basis to determine retiming needs. Exhibit 8-10 Example of Before-and-Aer Comparison: Time- Space Diagram When developing a project, it is important to determine the type of before-and-aer report that will be needed. Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-9 8.3.2 Monitor the Signal System Monitoring a signal system allows an operating agency to proactively make adjustments or respond in a timely and eficient manner to external input (e.g., public service requests). Signal system monitoring should include not only the functionality of signal timing parameters, but also signal system equipment (e.g., detection) that inluences intended timing operations. Common monitoring activities, which are described throughout this section, include • Operational monitoring, • Equipment monitoring, • Reviewing changes to agency policies or national standards, and • Responding to public service requests. If possible, it is desirable to use data that the signal system automatically collects to assess operational and equipment performance. For example, some signal systems can be programmed to collect data and graphically report various performance measures, as shown in Exhibit 8-12. However, obtaining meaningful real-time performance data from signalized intersections has historically been dificult because detection systems are not designed to provide good count information. Data are often summarized in averages that may not be calibrated, and access to the information is typically limited to personnel managing the signal system. Exhibit 8-11 Example of Before-and-Aer Comparison: Delay and Speed Graph Signal Timing Manual, Second Edion

8-10 Chapter 8. Implementaon and Maintenance 8.3.2.1 Operaonal Monitoring Operations at a signalized intersection or along a signalized corridor can change for a variety of reasons, including • Changes in trafic demand (e.g., change in minor street demand, change in turning movement volumes or spillback, change in major street demand, change in vehicle mix, or change in time-of-day volume distribution); • Changes in roadway geometry (e.g., addition of an approach lane or moving a bus stop from near-side to far-side); and • Changes in pedestrian trafic due to land use changes (e.g., the opening of a school or residence for the elderly). Operational monitoring can be conducted through relatively low-tech methods (e.g., signal operators traveling a corridor during their commute) or high-tech methods that use controller or central system functionality to actively monitor performance. Exhibit 8-13 provides examples of low- and high-tech methods for monitoring a signal system. Low-Tech Monitoring Acvies High-Tech Monitoring Acvies □ Scheduled intersecon visits □ Established commute routes for signal personnel to observe operaons during commute □ Public service requests □ Track growth areas and/or land use changes □ Track changes in crash pa­erns □ Mobile applicaons to monitor intended versus actual operaons □ Controller or system-based performance measure logs □ Permanent corridor travel me data collectors Exhibit 8-12 Example of Before-and-A…er Comparison: Percent Arrival on Green Exhibit 8-13 Operaonal Monitoring Acvies Signal Timing Manual, Second Edion

8-10 Chapter 8. Implementaon and Maintenance 8.3.2.1 Operaonal Monitoring Operations at a signalized intersection or along a signalized corridor can change for a variety of reasons, including • Changes in trafic demand (e.g., change in minor street demand, change in turning movement volumes or spillback, change in major street demand, change in vehicle mix, or change in time-of-day volume distribution); • Changes in roadway geometry (e.g., addition of an approach lane or moving a bus stop from near-side to far-side); and • Changes in pedestrian trafic due to land use changes (e.g., the opening of a school or residence for the elderly). Operational monitoring can be conducted through relatively low-tech methods (e.g., signal operators traveling a corridor during their commute) or high-tech methods that use controller or central system functionality to actively monitor performance. Exhibit 8-13 provides examples of low- and high-tech methods for monitoring a signal system. Low-Tech Monitoring Acvies High-Tech Monitoring Acvies □ Scheduled intersecon visits □ Established commute routes for signal personnel to observe operaons during commute □ Public service requests □ Track growth areas and/or land use changes □ Track changes in crash pa­erns □ Mobile applicaons to monitor intended versus actual operaons □ Controller or system-based performance measure logs □ Permanent corridor travel me data collectors Exhibit 8-12 Example of Before-and-A…er Comparison: Percent Arrival on Green Exhibit 8-13 Operaonal Monitoring Acvies Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-11 8.3.2.1.1 High-Resoluon Data “High-resolution” event data are an emerging source of data. Rather than storing the average values of data, individual time-stamped trafic events (i.e., when a detector turns on or off or when a phase turns green, yellow, or red) are logged in the controller, or in an external data collector, at a resolution of 0.1 seconds or faster. This type of data can support a variety of performance measures and other applications used to evaluate and improve signal operations (1). These performance measures have been successfully used by agencies in Indiana, Utah, Minnesota, and elsewhere. One application of high-resolution data is a visualization tool called the “Purdue Coordination Diagram” (PCD). The PCD is a useful tool that enables practitioners to quickly evaluate (1) how well a coordinated signal is operating on a particular approach and (2) operations before and after signal timing improvements are made (such as signal retiming or deployment of an advanced control system) (2). Exhibit 8-14 is an example PCD illustrating the operations on a coordinated approach over a 24-hour period. Information available in a PCD includes the following: • The dots represent vehicle arrivals as measured by a setback detector. These are plotted by time of day along the horizontal axis and by time during the cycle along the vertical axis. • The green and red lines show the start and end of green, respectively, during each cycle. Vehicle arrivals that occur above the green line represent arrivals during a green indication, while those occurring below the green line are arrivals during a red indication. • The upper red line is also indicative of the cycle length occurring at the intersection. Exhibit 8-14 shows coordinated operations that start at 6:00 a.m. and continue through the end of the day. The cycle length is 120 seconds, with some luctuation occurring due to actuation of the coordinated phase. Before 6:00 a.m. and after 10:00 p.m., cycle lengths luctuate considerably during fully- actuated, uncoordinated operations. • Platoons of vehicles are evident in the clustering of dots that occur throughout the day. Exhibit 8-14 shows that during the morning (6:00 a.m. to 9:00 a.m.), large clusters of vehicle arrivals are evident above the green line, which indicates arrivals on green (or good quality progression). In the afternoon (3:00 p.m. to 7:00 p.m.), this is not the case. The platoons arrive slightly before the start of green, which indicates an opportunity to improve progression (i.e., by adjusting the offsets). • The same data that are used to produce the PCD can also be used to compute a quantitative performance measure. For example, the percentage of vehicles arriving on green is shown for each coordination plan at the top of Exhibit 8-14. To demonstrate the utility of the PCD as an evaluation tool, Exhibit 8-15 illustrates operations at the same intersection after offsets have been optimized. During this study, the offsets for all of the timing plans were adjusted, but the afternoon plan (3:00 p.m. to 7:00 p.m.) experienced the most improved quality of progression. In Exhibit 8-15, more vehicle arrivals occur above the green line (i.e., vehicles were arriving on green), illustrating an improvement compared to the “before” case in Exhibit 8-14 (where vehicles were arriving on red). The percentage of arrival on green increased from 53.2 percent to 86.6 percent during the afternoon plan. Several vendors currently support “high-resoluon” data logging in the most recent versions of their controllers. Signal Timing Manual, Second Edion

8-12 Chapter 8. Implementaon and Maintenance 0 15 30 45 60 75 90 105 120 135 150 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Ti m e In C yc le (s ) Time of Day AM Peak 82.6% Midday 82.9% PM Peak 53.2% Evening 88.7%Not Coordinated Not Coord 0 15 30 45 60 75 90 105 120 135 150 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Ti m e In C yc le (s ) Time of Day AM Peak 86.8% Midday 89.9% PM Peak 86.6% Evening 87.4%Not Coordinated Not Coord Exhibit 8-14 Example of PCD: Before Offset Adjustment Exhibit 8-15 Example of PCD: Aer Offset Adjustment Signal Timing Manual, Second Edion

8-12 Chapter 8. Implementaon and Maintenance 0 15 30 45 60 75 90 105 120 135 150 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Ti m e In C yc le (s ) Time of Day AM Peak 82.6% Midday 82.9% PM Peak 53.2% Evening 88.7%Not Coordinated Not Coord 0 15 30 45 60 75 90 105 120 135 150 0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Ti m e In C yc le (s ) Time of Day AM Peak 86.8% Midday 89.9% PM Peak 86.6% Evening 87.4%Not Coordinated Not Coord Exhibit 8-14 Example of PCD: Before Offset Adjustment Exhibit 8-15 Example of PCD: Aer Offset Adjustment Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-13 8.3.2.2 Equipment Monitoring Equipment monitoring is often critical to effective signal timing and signal systems. Equipment failures can range from very noticeable issues (e.g., dark signals or signals in lash) to less noticeable system issues that may cause poor performance but are not as obvious (e.g., clock drift). Exhibit 8-16 lists potential signal-equipment-related issues that may affect signal timing. Signal-Equipment-Related Issue Descripon Signal Timing Impact Detector Fail/ Pedestrian Push Buon Fail Failure indicaon of a detector (e.g., fail on, fail off, or chaer). Fail on results in maximum recall, regardless of user demand. Fail off results in user demand not being served, encouraging control violaons due to excessive delay. Count Irregularity Detected discrepancy in counts on a movement found by comparing recent or real-me counts against an expected profile. None, unless ming is related to measured volume (e.g., responsive, adapve, or condional service). Controller Status Online/offline status and/or failure mode indicaon of a traffic signal controller. Offline limits remote ming changes, monitoring, log access, etc. Failure modes have varying impacts. Alarms Number of controller alarms reported. Varies. Controller Parameter Inconsistency Detected discrepancy in controller parameter se‹ngs found by comparing actual and expected controller parameters (likely in a database). Varies. Timing Irregularity Detected discrepancy in ming for a movement found by comparing real-me ming against an expected condion. Varies. Clock Synchronizaon Check for correct local controller clock se‹ng. Loss of progression. Transion Frequency The number of mes and duraon that a signal is reported in transion. Varies, some transion is normal; excessive transion may indicate a problem. Flash/Conflict Frequency The number of flash/conflict events, by type if available. Varies, but typically is very disrupve to traffic. Power Source Signal operang on normal or back-up power. Signal not operang on normal power supply may be in flash. Communicaon Quality The number of successful, failed, and bad poll messages; poron of me a device is connected or disconnected via communicaon. Offline limits remote ming changes, monitoring, log access, etc. Failure modes have varying impacts. Response Time How long to repair a detected issue. Varies. Repair Frequency Frequency of repair to a consistent issue and/or locaon. Varies. The health of signal equipment should be assessed prior to timing update efforts. For example, if vehicle detection for a left-turn movement is discovered to have failed, Exhibit 8-16 Potenal Signal-Equipment- Related Issues Signal Timing Manual, Second Edion

8-14 Chapter 8. Implementaon and Maintenance the detection should be ixed prior to making signal timing adjustments. In order to streamline signal timing efforts, the operating agency should maintain a database of signal equipment, where technicians can record any signal equipment failures or changes that occur. 8.3.2.3 Reviewing Changes to Agency Policies and Naonal Standards Agency policies and national standards inluence both overarching agency objectives and speciic signal timing parameters. A practitioner should monitor changes to policies and standards because they may impact when signal timing updates are made to certain signals and how values are chosen for signal timing parameters. For example, a city might have a new comprehensive plan that includes a goal to improve bicycle routes around the city. While vehicle delay may have been the primary evaluation tool before, the number of stops for bicyclists could now be an important measure for certain routes, which would require the signal timing to be adjusted. On a national level, the Manual on Uniform Trafic Control Devices for Streets and Highways (MUTCD, 3) inluences speciic signal timing parameters. The MUTCD recently changed the walking speed used to calculate pedestrian intervals (from 4 feet per second to 3.5 feet per second), which necessitates an update at all intersections timed under the old standard. It is important for a practitioner to stay apprised of these types of changes so that signal systems remain current. 8.3.2.4 Responding to Public Service Requests Citizen input is one of the most common reasons for reviewing intersection operations. The public may give input for any number of reasons, including • A lack of understanding of intersection and controller operations, • A signal that was in transition between two different timing plans, • An equipment failure, • A legitimate observation regarding a shortcoming in the existing timing, or • An incident near or at the intersection that impacted trafic operations. Citizens often have a sophisticated understanding of intersection operations resulting from their familiarity with a given roadway. For this reason, as well as for possible reasons of safety, their input should be taken very seriously. Each agency should have a process in place to receive public input and address concerns in a timely, professional manner. 8.3.2.4.1 Collecng Data from the Public A well-managed operating agency will employ a procedure similar to that below in response to public input (which could arrive by telephone, email, or a letter): 1. Identify the name and contact information of the caller. 2. Identify the location where the problem occurred. 3. Deine the time of day when the problem was observed. 4. Determine whether the problem is recurring. Some agencies include a scker with a logo, phone number, and catch phrase on the outside of the traffic signal controller cabinet to assist the public with obtaining the correct contact informaon. Signal Timing Manual, Second Edion

8-14 Chapter 8. Implementaon and Maintenance the detection should be ixed prior to making signal timing adjustments. In order to streamline signal timing efforts, the operating agency should maintain a database of signal equipment, where technicians can record any signal equipment failures or changes that occur. 8.3.2.3 Reviewing Changes to Agency Policies and Naonal Standards Agency policies and national standards inluence both overarching agency objectives and speciic signal timing parameters. A practitioner should monitor changes to policies and standards because they may impact when signal timing updates are made to certain signals and how values are chosen for signal timing parameters. For example, a city might have a new comprehensive plan that includes a goal to improve bicycle routes around the city. While vehicle delay may have been the primary evaluation tool before, the number of stops for bicyclists could now be an important measure for certain routes, which would require the signal timing to be adjusted. On a national level, the Manual on Uniform Trafic Control Devices for Streets and Highways (MUTCD, 3) inluences speciic signal timing parameters. The MUTCD recently changed the walking speed used to calculate pedestrian intervals (from 4 feet per second to 3.5 feet per second), which necessitates an update at all intersections timed under the old standard. It is important for a practitioner to stay apprised of these types of changes so that signal systems remain current. 8.3.2.4 Responding to Public Service Requests Citizen input is one of the most common reasons for reviewing intersection operations. The public may give input for any number of reasons, including • A lack of understanding of intersection and controller operations, • A signal that was in transition between two different timing plans, • An equipment failure, • A legitimate observation regarding a shortcoming in the existing timing, or • An incident near or at the intersection that impacted trafic operations. Citizens often have a sophisticated understanding of intersection operations resulting from their familiarity with a given roadway. For this reason, as well as for possible reasons of safety, their input should be taken very seriously. Each agency should have a process in place to receive public input and address concerns in a timely, professional manner. 8.3.2.4.1 Collecng Data from the Public A well-managed operating agency will employ a procedure similar to that below in response to public input (which could arrive by telephone, email, or a letter): 1. Identify the name and contact information of the caller. 2. Identify the location where the problem occurred. 3. Deine the time of day when the problem was observed. 4. Determine whether the problem is recurring. Some agencies include a scker with a logo, phone number, and catch phrase on the outside of the traffic signal controller cabinet to assist the public with obtaining the correct contact informaon. Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-15 5. Ask for a description of the problem in terms of traf ic conditions and traf ic signal operations. (For example, if preemption exists at the signal, ask the caller if there were emergency vehicles or rail activity.) 6. Assure the caller that the problem will be investigated within a prede ined number of days that has been established by agency policy. 7. Enter all information provided, along with the time and date of the contact, into a database. Investigation of the problem should be scheduled as part of the agency’s maintenance or operations program. If signal timing adjustments are required, the procedures described later in this chapter can be used to address the problem. In all cases, the results of the investigation should (1) be recorded in a database (or written documents) and (2) communicated to the person who made the request using the same media (e.g., telephone, email, or mail) that was used to make the original contact. If no change was made, the reason for maintaining the status quo should be explained. A website may be used to record input and provide an estimate of response time, as well as to provide a way to maintain the records database. This is a particularly effective technique in regions where multiple jurisdictions are involved with signal operations and maintenance. Establishing a regional website allows problems and public service requests to be directed to the appropriate agency without requiring callers to determine the responsible agency themselves. While some agencies utilize sophisticated call-processing software that handles the database functions described here, smaller agencies may ind simple spreadsheets to be just as effective for keeping track of public service requests. In either case, it is critical to ensure that all calls are investigated and that a response is provided to the caller in a timely manner. Ideally, a response should be received by the caller within 1 week of the date that the initial contact was made. 8.3.2.4.2 Invesgang Service Requests After information has been collected from the public about a perceived problem, the irst task for the operating agency is to identify whether the reported problem is related to the operation of the signal. Commonly reported issues that are unrelated to signal operations include • A dark signal due to a power outage, • A signal with damaged hardware, • A burned-out bulb, and • A signal-monitor lash. Exhibit 8-17 includes examples of common public service requests that are related to signal operations, as well as questions that the operating agency should consider when trying to address these problems. When evaluating a problem in the ield, a diagnosis of the potential operational problem should be made before opening the signal cabinet door, unless there is a current safety issue. Responsive service is the key to good customer relaons. Diagnose the operaonal problem before opening the cabinet door, unless there is an immediate safety issue. Signal Timing Manual, Second Edion

8-16 Chapter 8. Implementaon and Maintenance Signal Operaons Category Example Public Service Requests Potenal Quesons to Idenfy a Soluon Not Geng a Green □ “My movement is not geng a green.” □ Is the intersecon part of a coordinated system (that dedicates me to certain phases for progression)? □ Have the detectors been damaged? □ Is the stopping point well defined (so that vehicles will stop over the detectors)? □ Is the detecon zone appropriate (e.g., large enough to detect vehicles in a wide approach, sensive enough to detect bicycles)? □ How are the detectors being operated? Is the non-locking seng being used when needed? □ Was preempon acve? Short Green □ “My movement gets a green, but the green is too short.” □ If the intersecon is part of a coordinated system, is the correct plan running? □ Are the splits appropriate and customized for the intersecon? □ If the parcular phase is on recall, are the detectors working properly? □ Was preempon acve? □ If it is a mul-lane approach, is a lane temporarily out of service due to construcon or incomplete snow plowing? □ Is the approach on a steep grade, where a slippery road could affect performance? Excessive Delay Before Green □ “My movement gets a green, but the delay is excessive.” □ If the intersecon is part of a coordinated system, is the correct ming plan running? □ How are offset adjustments being made? □ Are detectors located appropriately (so that the first vehicle places a call)? □ Was preempon acve (potenally for a long me, if an emergency vehicle pulled over with the emi‡er sll running)? Protected LeŠ- Turn Delay □ “When I am making a leŠ turn, why do I have to wait for the arrow when there is no traffic?” □ Would protected-permi‡ed leŠ-turn phasing be appropriate? □ Should the protected movement be restricted to certain mes of day or certain traffic condions? Unexpected Stops at a Second Signal AŠer Leaving the First Signal □ “I leave one signal, and then I am suddenly stopped at the next signal.” □ Are the intersecons closely spaced and not coordinated? □ If the intersecons are coordinated, is this condion predicted (such as in the off-peak direcon of a one-way progression plan)? □ If coordinated, is the first intersecon experiencing early release because of light traffic (that could be addressed through a split or offset adjustment)? □ How are offset adjustments being made? □ If the intersecons are part of a coordinated system and on the major street, are the extended detectors at the second intersecon working correctly? □ If the approach phase at the second intersecon is on recall or running semi-actuated, is there a detector malfuncon? □ Are the intersecons part of an adapve system and in a locaon with speeds greater than 40 miles per hour (mph)? Depending on the system, there may or may not be setback detecon (or even detecon directly controlling the length of individual green intervals). Exhibit 8-17 Public Service Requests and Associated Signal Operaons Consideraons Signal Timing Manual, Second Edion

8-16 Chapter 8. Implementaon and Maintenance Signal Operaons Category Example Public Service Requests Potenal Quesons to Idenfy a Soluon Not Geng a Green □ “My movement is not geng a green.” □ Is the intersecon part of a coordinated system (that dedicates me to certain phases for progression)? □ Have the detectors been damaged? □ Is the stopping point well defined (so that vehicles will stop over the detectors)? □ Is the detecon zone appropriate (e.g., large enough to detect vehicles in a wide approach, sensive enough to detect bicycles)? □ How are the detectors being operated? Is the non-locking seng being used when needed? □ Was preempon acve? Short Green □ “My movement gets a green, but the green is too short.” □ If the intersecon is part of a coordinated system, is the correct plan running? □ Are the splits appropriate and customized for the intersecon? □ If the parcular phase is on recall, are the detectors working properly? □ Was preempon acve? □ If it is a mul-lane approach, is a lane temporarily out of service due to construcon or incomplete snow plowing? □ Is the approach on a steep grade, where a slippery road could affect performance? Excessive Delay Before Green □ “My movement gets a green, but the delay is excessive.” □ If the intersecon is part of a coordinated system, is the correct ming plan running? □ How are offset adjustments being made? □ Are detectors located appropriately (so that the first vehicle places a call)? □ Was preempon acve (potenally for a long me, if an emergency vehicle pulled over with the emi‡er sll running)? Protected LeŠ- Turn Delay □ “When I am making a leŠ turn, why do I have to wait for the arrow when there is no traffic?” □ Would protected-permi‡ed leŠ-turn phasing be appropriate? □ Should the protected movement be restricted to certain mes of day or certain traffic condions? Unexpected Stops at a Second Signal AŠer Leaving the First Signal □ “I leave one signal, and then I am suddenly stopped at the next signal.” □ Are the intersecons closely spaced and not coordinated? □ If the intersecons are coordinated, is this condion predicted (such as in the off-peak direcon of a one-way progression plan)? □ If coordinated, is the first intersecon experiencing early release because of light traffic (that could be addressed through a split or offset adjustment)? □ How are offset adjustments being made? □ If the intersecons are part of a coordinated system and on the major street, are the extended detectors at the second intersecon working correctly? □ If the approach phase at the second intersecon is on recall or running semi-actuated, is there a detector malfuncon? □ Are the intersecons part of an adapve system and in a locaon with speeds greater than 40 miles per hour (mph)? Depending on the system, there may or may not be setback detecon (or even detecon directly controlling the length of individual green intervals). Exhibit 8-17 Public Service Requests and Associated Signal Operaons Consideraons Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-17 Signal Operaons Category Example Public Service Requests Potenal Quesons to Idenfy a Soluon Signal Serves Approach or Movement with no Demand □ “I am waing while an approach with no traffic is served before me.” □ Is there unnecessary locking memory? □ Is the phase on recall? □ Are detecon zones misplaced? □ Is there right-turn-on-red with inappropriate detecon and delay seƒngs? Red Light Running □ “I see a lot of red light running.” □ Are the yellow change and red clearance intervals set appropriately? □ Is the minimum green set appropriately (or will drivers be surprised by a short green)? □ Is the cycle length appropriate? Drivers who are familiar with a signal that has a long cycle length may be encouraged to run the red light instead of waing through another cycle. □ Are the detectors placed in an appropriate locaon? □ Do the detectors provide adequate decision zone protec on? Near Misses □ “I see a lot of near misses.” □ Are the yellow change and red clearance intervals set appropriately? □ Is the minimum green set appropriately (or will drivers be surprised by a short green)? □ Is the cycle length appropriate? Drivers who are familiar with a signal that has a long cycle length may be encouraged to run the red light instead of wai ng through another cycle. □ Are the detectors placed in an appropriate loca on? □ Do the detectors provide adequate decision zone protec on? □ If le -turn movements are permi€ed, should a por on of the movement be protected? □ If le -turn movements are protected-permi€ed, should the ming and detec on for the protected interval be revised? Short Walk Time □ “I only get partway into the intersec on and the flashing don’t walk comes on.” □ Does the caller understand how a pedestrian phase is med and what the indica ons mean? □ Is there heavy pedestrian ac vity or heavy turning vehicle traffic across the crosswalk that would jus fy a longer walk interval? □ Is the advance walk feature appropriate? Short Flashing Don’t Walk Interval □ “I cannot finish crossing during the flashing don’t walk.” □ Does the caller understand how a pedestrian phase is med and what the indica ons mean? □ Does the intersec on serve elderly or young pedestrians that would require a longer pedestrian clearance me? □ Does the intersec on have heavy turning vehicle traffic across the crosswalk that would jus fy a longer pedestrian clearance me? Delay in Ge‘ng Walk □ “I push the bu€on, and it takes a long me to get a walk.” □ Does the caller understand how a pedestrian phase is med and what the indica ons mean? □ Are the push bu€ons opera ng properly? □ Is the cycle length too long for condi ons? □ Can the signal be operated in free mode? Don’t Walk Understanding □ “I see a circular green, but I don’t get a walk (even though I pushed the bu€on). When I start to cross, le - turning traffic nearly hits me.” □ Is split phasing being used (where a pedestrian may be confused about conflic ng traffic) without the use of le -arrow displays? Signal Timing Manual, Second Edion

8-18 Chapter 8. Implementaon and Maintenance Signal Operaons Category Example Public Service Requests Potenal Quesons to Idenfy a Soluon Emergency Preempon Understanding □ “When an emergency vehicle goes through the intersecon, the signal operates “funny,” and what does the flashing white light mean?” □ Would a public informaon effort be appropriate? Railroad Preempon Understanding □ “When a train goes through the crossing adjacent to the intersecon and I am on the other roadway, the delays are excessive.” □ Is the system operang as designed? □ Is the preempon operaon efficient? Railroad Crossing Understanding □ “When I am on an approach to a signal with a railroad crossing right at the intersecon, I am not sure what I should do.” □ Is the preempon ming correctly (parcularly the track clearance phase ming and the ming of pedestrian intervals)? □ Are appropriate signs provided on each approach? □ Is detecon working appropriately (parcularly on the approach behind the tracks)? Night Flash Operaons □ “Late at night, the signal creates excessive delay, and there is li’le to no traffic. Why can’t it be in flash?” □ “The signal is sll in flash in the morning when traffic gets heavy.” □ What is the agency’s night flash policy? □ Are the hours of flash set correctly in the controller? □ Have the peak periods shi–ed during the day (requiring flash to be run during different hours)? □ Is the me (set in the controller or, alternavely, in the me- switch that controls flash) set correctly? 8.3.3 Perform Maintenance Updates If deiciencies are identiied as part of the monitoring activities explained in the previous section, the following process can be used to make signal timing updates. Because updates are made for a variety of reasons, the following process should only be used as a starting point, with adaptations made on a case-by-case basis. Before heading to the ield to address a signal timing problem, the operating agency should complete the following activities: • Determine the possible presence of maintenance or construction activity at or near the signal in question. • Assess the trafic conditions likely to be experienced during the time of day when the problem was observed. A review of available trafic data may be required. • Review previous retiming reports, if available. Signal ming updates are different from the systemac reming efforts discussed in Chapters 5–7, but the field work will ulize a procedure similar to that used for implementaon of a new ming plan (described previously in this chapter). Signal Timing Manual, Second Edion

8-18 Chapter 8. Implementaon and Maintenance Signal Operaons Category Example Public Service Requests Potenal Quesons to Idenfy a Soluon Emergency Preempon Understanding □ “When an emergency vehicle goes through the intersecon, the signal operates “funny,” and what does the flashing white light mean?” □ Would a public informaon effort be appropriate? Railroad Preempon Understanding □ “When a train goes through the crossing adjacent to the intersecon and I am on the other roadway, the delays are excessive.” □ Is the system operang as designed? □ Is the preempon operaon efficient? Railroad Crossing Understanding □ “When I am on an approach to a signal with a railroad crossing right at the intersecon, I am not sure what I should do.” □ Is the preempon ming correctly (parcularly the track clearance phase ming and the ming of pedestrian intervals)? □ Are appropriate signs provided on each approach? □ Is detecon working appropriately (parcularly on the approach behind the tracks)? Night Flash Operaons □ “Late at night, the signal creates excessive delay, and there is li’le to no traffic. Why can’t it be in flash?” □ “The signal is sll in flash in the morning when traffic gets heavy.” □ What is the agency’s night flash policy? □ Are the hours of flash set correctly in the controller? □ Have the peak periods shi–ed during the day (requiring flash to be run during different hours)? □ Is the me (set in the controller or, alternavely, in the me- switch that controls flash) set correctly? 8.3.3 Perform Maintenance Updates If deiciencies are identiied as part of the monitoring activities explained in the previous section, the following process can be used to make signal timing updates. Because updates are made for a variety of reasons, the following process should only be used as a starting point, with adaptations made on a case-by-case basis. Before heading to the ield to address a signal timing problem, the operating agency should complete the following activities: • Determine the possible presence of maintenance or construction activity at or near the signal in question. • Assess the trafic conditions likely to be experienced during the time of day when the problem was observed. A review of available trafic data may be required. • Review previous retiming reports, if available. Signal ming updates are different from the systemac reming efforts discussed in Chapters 5–7, but the field work will ulize a procedure similar to that used for implementaon of a new ming plan (described previously in this chapter). Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-19 • If the intersection has remote monitoring capabilities, the problem should be investigated with that tool irst. In particular, performance monitoring logs may be helpful. If the operating agency is not able to determine a solution based on ofice activities, a ield visit may be warranted, and the following procedure can be employed: • Schedule a ield visit for the time of day and type of day (e.g., weekend or weekday) during which the problem was identiied. • Assemble the timing and coniguration information for the intersection being visited. Timing information should include controller settings and, if available, trafic count data. If the intersection is part of a system, the information should also include the master clock, offsets, and time-of-day schedules. • If the intersection is included in a system, coordinate with system operators to ensure that operations personnel will be available to support the ield activities. • When arriving at the intersection, observe the physical condition of the street hardware (including the poles, mast arms or span wires, signal heads, detection, pedestrian displays, and cabinet). Make a preliminary assessment of the existence of a problem and its likely cause before opening the cabinet (unless an obvious safety problem needs to be immediately addressed). • Open the cabinet and check the log book, and then perform a physical inspection of the cabinet interior (including cabling, physical condition and operation of cabinet components, air ilter, and fan). • Check operability of all cabinet components either through observation or suitable maintenance diagnostics. • Review controller timing by comparing settings with timing documentation. • Qualitatively compare trafic conditions at the intersection with the trafic count data (data must be for same time period). Determine whether major changes in demand have occurred since the trafic counts were taken to support the development of the timing plans currently in use. If major changes have occurred, determine whether they are temporary (e.g., due to nearby construction) or permanent. If they are temporary, it may still be desirable to update the intersection timing. However, include a note in the maintenance log (and any other cabinet documentation) that a second signal timing update may be required when construction is complete. • In all cases, after timing and/or scheduling changes have been made, the impact of the changes should be evaluated through observation of the intersection operations. • The inal step of this process is to log the actions taken. This is essential for responding to the individual who initiated the maintenance, as well as records that must be maintained by the operating agency for a variety of engineering, operational, and legal reasons. 8.3.3.1 Common Timing Updates for Under-Saturated Condions It is likely that the most frequent requests for intersection maintenance will occur during normal low conditions. These are the conditions that impact a large number of Signal Timing Manual, Second Edion

8-20 Chapter 8. Implementaon and Maintenance roadway users, who all expect high signal timing quality. Users will be annoyed at instances of wasted green time when they are waiting at a red signal indication with no vehicles on other phases or when they have to stop at successive signals due to poor offsets. When retiming an intersection for under-saturated (free-low) conditions, the following steps are recommended: • Perform a qualitative evaluation of the intersection performance to determine whether any obvious improvements are possible. • Adjust the splits to relect demand on competing approaches. • Adjust the offsets to relect platoon arrival times. • Adjust the start and end times of timing plans (in the time-of-day plan). • Review the cycle length to determine the need for a new timing study. 8.3.3.2 Common Timing Updates for Oversaturated Condions It is important to recognize the need for different trafic signal timing strategies for networks that experience oversaturated trafic conditions (i.e., demand exceeds intersection capacity). Strategies begin to change from mobility and progression to queue management. When initially assessing signal timing at a congested intersection, the splits (irst) and cycle length (second) should be reviewed and adjusted if possible to reduce the congestion. (Note that congestion may exist for some users because of higher-priority operational objectives for other users.) If typical under-saturated adjustments are not able to produce reasonable results, then oversaturated techniques (discussed in Chapter 12) may be necessary. However, the presence of congestion should not immediately cause a practitioner to assume that there is excessive demand. In many cases, congestion is the result of poor signal timing parameters, especially excessively long cycle lengths or bad offsets that do not promote progression. 8.4 STAFFING NEEDS An agency may need a variety of staff positions and roles to adequately operate and maintain its trafic signal system. The size and breadth of the staff dedicated to trafic signal operations and maintenance should depend primarily on the size and complexity of the system. 8.4.1 Staff Posi ons Larger organizations have specialized staff to support signal systems. Depending on the size of the signal system, some of these positions may be combined. The roles of each position described below are based on information from agencies and relevant Institute of Transportation Engineers (ITE) and Federal Highway Administration (FHWA) literature: • Trafic Signal Engineer: This staff person is responsible for the day-to-day operations of the signal system. Tasks include responding to public comments, approving new signal turn-on’s, assisting in the TMC, evaluating signal timing on existing arterials, managing signal operations staff, and coordinating with the signal design and maintenance supervisors. Congeson can be recognized by the presence of queues (at signalized intersecons) that are not completely discharged during the green period. Chapter 12 has addional informaon on symptoms of oversaturaon. The important point is that a complete set of skills is needed to operate and maintain a traffic signal system, but those skills can reside in different combinaons of staff posions. Signal Timing Manual, Second Edi on

8-20 Chapter 8. Implementaon and Maintenance roadway users, who all expect high signal timing quality. Users will be annoyed at instances of wasted green time when they are waiting at a red signal indication with no vehicles on other phases or when they have to stop at successive signals due to poor offsets. When retiming an intersection for under-saturated (free-low) conditions, the following steps are recommended: • Perform a qualitative evaluation of the intersection performance to determine whether any obvious improvements are possible. • Adjust the splits to relect demand on competing approaches. • Adjust the offsets to relect platoon arrival times. • Adjust the start and end times of timing plans (in the time-of-day plan). • Review the cycle length to determine the need for a new timing study. 8.3.3.2 Common Timing Updates for Oversaturated Condions It is important to recognize the need for different trafic signal timing strategies for networks that experience oversaturated trafic conditions (i.e., demand exceeds intersection capacity). Strategies begin to change from mobility and progression to queue management. When initially assessing signal timing at a congested intersection, the splits (irst) and cycle length (second) should be reviewed and adjusted if possible to reduce the congestion. (Note that congestion may exist for some users because of higher-priority operational objectives for other users.) If typical under-saturated adjustments are not able to produce reasonable results, then oversaturated techniques (discussed in Chapter 12) may be necessary. However, the presence of congestion should not immediately cause a practitioner to assume that there is excessive demand. In many cases, congestion is the result of poor signal timing parameters, especially excessively long cycle lengths or bad offsets that do not promote progression. 8.4 STAFFING NEEDS An agency may need a variety of staff positions and roles to adequately operate and maintain its trafic signal system. The size and breadth of the staff dedicated to trafic signal operations and maintenance should depend primarily on the size and complexity of the system. 8.4.1 Staff Posi ons Larger organizations have specialized staff to support signal systems. Depending on the size of the signal system, some of these positions may be combined. The roles of each position described below are based on information from agencies and relevant Institute of Transportation Engineers (ITE) and Federal Highway Administration (FHWA) literature: • Trafic Signal Engineer: This staff person is responsible for the day-to-day operations of the signal system. Tasks include responding to public comments, approving new signal turn-on’s, assisting in the TMC, evaluating signal timing on existing arterials, managing signal operations staff, and coordinating with the signal design and maintenance supervisors. Congeson can be recognized by the presence of queues (at signalized intersecons) that are not completely discharged during the green period. Chapter 12 has addional informaon on symptoms of oversaturaon. The important point is that a complete set of skills is needed to operate and maintain a traffic signal system, but those skills can reside in different combinaons of staff posions. Signal Timing Manual, Second Edi on Chapter 8. Implementaon and Maintenance 8-21 • Trafic Signal Technician/Analyst: This staff person assists the trafic signal engineer with his or her day-to-day operations. Focus areas include signal timing, new signals, and the TMC. • Intelligent Transportation Systems (ITS) Engineer: This staff person is responsible for the implementation of ITS projects. Tasks include responding to public comments, evaluating new products, assisting in the TMC, managing ITS contractors and vendors, and coordinating with the signal design and maintenance supervisors. • Trafic Signal Maintenance Technician: This staff person is generally responsible for troubleshooting and maintenance of the physical trafic signal equipment. • Electronic/Communications Specialist: This staff person is responsible for the complex electronic equipment at the heart of the signal system. Some tasks include closed-circuit television (CCTV) system repair (ield and central system); iber-optic-cable system testing, repair, and termination; telecommunications system maintenance and repair; TMC system maintenance and repair; trafic signal controller electronics testing, repair, and inventory; and other ITS devices repair. The skills required include knowledge of Ethernet communications, databases, troubleshooting software, and an understanding of the software that monitors, maintains, and runs the system. Information Technology (IT) skills are a vital part of a successful system. • TMC Operator: This staff person is responsible for observing trafic conditions, responding to incidents that occur in the ield, and providing support to homeland security efforts. This role is critical to the rapid response and resolution of signal system situations. • Public Relations Coordinator: This staff person is responsible for ielding phone calls from the public, coordinating with the trafic signal engineer and technician/analyst on responses, and marketing the TMC, incident management plan, and trafic signal operations to the public. Depending on the size of the agency, this position could be a full-time position or these tasks might be passed on to the trafic signal engineer and technician/analyst. Proximity to trafic signals is an important consideration when determining stafing needs, particularly for technicians who are tasked with responding to public service requests or maintenance problems. A city with a large downtown may have 100 signals within 1 square mile, as opposed to a rural district with 100 signals over 1000 square miles. Obviously, in these cases, the stafing needs are likely different and may require different skillsets and stafing levels. Additional information regarding stafing needs has been summarized in several publications, including • ITE Trafic Engineering Handbook (4) and ITE Trafic Control System Operations: Installation, Management, and Maintenance (5). These texts suggest labor requirements of 20 to 25 hours per intersection for trafic signal retiming. They estimate that one trafic engineer is needed to properly operate and maintain every 75 to 100 signals and that one technician is needed to properly operate and maintain every 40 to 50 signals. While good rules of Signal Timing Manual, Second Edion

8-22 Chapter 8. Implementaon and Maintenance thumb, the current transportation environment requires much more detailed estimates. • FHWA Trafic Signal Operations and Maintenance Stafing Guidelines (6). This publication provides stafing and resource guidance for agencies in order to help them effectively operate and maintain their trafic signal systems. Surveys performed by FHWA as background for these guidelines indicate that agencies are able to achieve a high level of performance under a wide variety of signal system conditions. Because of the wide variety of successful stafing and resource combinations, performance-based criteria were developed to help agencies deine realistic and concise objectives and performance measures, which can then be used to estimate stafing and resource needs. 8.4.2 Staff Training A valuable component of trafic signal maintenance is ensuring that the staff managing and maintaining the trafic signals has been trained to operate the system. Training can include activities such as peer exchanges (within or between agencies), technical sessions with outside experts, or attending conferences, educational seminars, or universities. Critical training elements highlighted in the FHWA Guidelines for Transportation Management Systems: Maintenance Concept and Plans (7) include • Training by Vendors. Procurement contracts should include a requirement for on-site training of agency staff in maintenance and operation of the equipment, preferably conducted by the vendor. • Training by Contractors. Procurement contracts should also include a requirement for on-site training of agency staff in the maintenance and operation of the assembled systems, including software, hardware, and devices. • Training Library. The operating agency should maintain a library of system documentation and, if available, a video library of training materials. • Staff Retention. This can be dificult in a high-tech environment, but there are ways to improve retention, such as supporting additional training, allowing travel to technical conferences and workshops, and providing other beneits for agency staff. In addition to internal staff training, the operating agency might also consider hosting short work sessions or seminars that are open to the public and other agency oficials. External training gives roadway users the opportunity to gain insight into signal timing and trafic operations, which only enhances the external input received for monitoring and maintenance activities. 8.5 REFERENCES 1. Day, C. M., D. M. Bullock, H. Li, S. M. Remias, A. M. Hainen, R. S. Freije, A. L. Stevens, J. R. Sturdevant, and T. M. Brennan. Performance Measures for Trafic Signal Systems: An Outcome-Oriented Approach. Purdue University, West Lafayette, Indiana, 2014. The equipment and soware u lized by many agencies for their traffic signal systems are only as good as the availability of skilled and trained staff. Signal Timing Manual, Second Edion

8-22 Chapter 8. Implementaon and Maintenance thumb, the current transportation environment requires much more detailed estimates. • FHWA Trafic Signal Operations and Maintenance Stafing Guidelines (6). This publication provides stafing and resource guidance for agencies in order to help them effectively operate and maintain their trafic signal systems. Surveys performed by FHWA as background for these guidelines indicate that agencies are able to achieve a high level of performance under a wide variety of signal system conditions. Because of the wide variety of successful stafing and resource combinations, performance-based criteria were developed to help agencies deine realistic and concise objectives and performance measures, which can then be used to estimate stafing and resource needs. 8.4.2 Staff Training A valuable component of trafic signal maintenance is ensuring that the staff managing and maintaining the trafic signals has been trained to operate the system. Training can include activities such as peer exchanges (within or between agencies), technical sessions with outside experts, or attending conferences, educational seminars, or universities. Critical training elements highlighted in the FHWA Guidelines for Transportation Management Systems: Maintenance Concept and Plans (7) include • Training by Vendors. Procurement contracts should include a requirement for on-site training of agency staff in maintenance and operation of the equipment, preferably conducted by the vendor. • Training by Contractors. Procurement contracts should also include a requirement for on-site training of agency staff in the maintenance and operation of the assembled systems, including software, hardware, and devices. • Training Library. The operating agency should maintain a library of system documentation and, if available, a video library of training materials. • Staff Retention. This can be dificult in a high-tech environment, but there are ways to improve retention, such as supporting additional training, allowing travel to technical conferences and workshops, and providing other beneits for agency staff. In addition to internal staff training, the operating agency might also consider hosting short work sessions or seminars that are open to the public and other agency oficials. External training gives roadway users the opportunity to gain insight into signal timing and trafic operations, which only enhances the external input received for monitoring and maintenance activities. 8.5 REFERENCES 1. Day, C. M., D. M. Bullock, H. Li, S. M. Remias, A. M. Hainen, R. S. Freije, A. L. Stevens, J. R. Sturdevant, and T. M. Brennan. Performance Measures for Trafic Signal Systems: An Outcome-Oriented Approach. Purdue University, West Lafayette, Indiana, 2014. The equipment and soware u lized by many agencies for their traffic signal systems are only as good as the availability of skilled and trained staff. Signal Timing Manual, Second Edion Chapter 8. Implementaon and Maintenance 8-23 2. Day, C. M., R. Haseman, H. Premachandra, T. M. Brennan, Jr., J. S. Wasson, J. R. Sturdevant, and D. M. Bullock. Evaluation of Arterial Signal Coordination: Methodologies for Visualizing High-Resolution Event Data and Measuring Travel Time. In Transportation Research Record: Journal of the Transportation Research Board, No. 2192, Transportation Research Board of the National Academies, Washington, D.C., 2010, pp. 37–49. 3. Manual on Uniform Trafic Control Devices for Streets and Highways, 2009 Edition. United States Department of Transportation, Federal Highway Administration, Washington, D.C., 2009. 4. Trafic Engineering Handbook, 6th Edition. Institute of Transportation Engineers, Washington, D.C., 2009. 5. Giblin, J. M., and W. H. Kraft. Trafic Control System Operations: Installation, Management, and Maintenance. Institute of Transportation Engineers, Washington, D.C., 2000. 6. Gordon, R., and C. Braud. Trafic Signal Operations and Maintenance Stafing Guidelines. Report FHWA-HOP-09-006, Federal Highway Administration, United States Department of Transportation, 2009. 7. Vick, C., and R. Sumner. Guidelines for Transportation Management Systems: Maintenance Concept and Plans. Report FHWA-OP-04-011, Federal Highway Administration, United States Department of Transportation, 2002. Signal Timing Manual, Second Edion

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TRB’s National Cooperative Highway Research Program (NCHRP) Report 812: Signal Timing Manual - Second Edition, covers fundamentals and advanced concepts related to signal timing. The report addresses ways to develop a signal timing program based on the operating environment, users, user priorities by movement, and local operational objectives.

Advanced concepts covered in the report include the systems engineering process, adaptive signal control, preferential vehicle treatments, and timing strategies for over-saturated conditions, special events, and inclement weather.

An overview PowerPoint presentation accompanies the report.

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