National Academies Press: OpenBook

Performance-Based Management of Traffic Signals (2020)

Chapter: Chapter 1 - Roadmap to Performance Measures

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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
×
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
×
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
×
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
×
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
×
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Suggested Citation:"Chapter 1 - Roadmap to Performance Measures." National Academies of Sciences, Engineering, and Medicine. 2020. Performance-Based Management of Traffic Signals. Washington, DC: The National Academies Press. doi: 10.17226/25875.
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CHAPTER 1 ROADMAP TO PERFORMANCE MEASURES 1.1 SIGNAL PERFORMANCE MEASURE BASICS 4 1.2 SIGNAL PERFORMANCE MEASURE BENEFITS 6 1.3 INVESTING IN SIGNAL PERFORMANCE MEASURES 8 1.4 IMPLEMENTING SIGNAL PERFORMANCE MEASURES 9 1.5 REFERENCE 11 LIST OF EXHIBITS EXHIBIT 1-1. FLOW OF INFORMATION 5 EXHIBIT 1-2. TRADITIONAL VERSUS PERFORMANCE-BASED SIGNAL TIMING PROCESS 5 EXHIBIT 1-3. SIGNAL PERFORMANCE MEASURE BENEFITS 6 EXHIBIT 1-4. STAKEHOLDER ROLES, OBJECTIVES, AND SIGNAL PERFORMANCE MEASURE BENEFITS 7 EXHIBIT 1-5. ACTIVITIES THAT SUPPORT SIGNAL PERFORMANCE MEASURES BY STAFF LEVEL 8 EXHIBIT 1-6. ROADMAP FOR IMPLEMENTING SIGNAL PERFORMANCE MEASURES 9

CHAPTER FOCUS Chapter 1 is a roadmap to signal performance measures, providing basic information and a summary of benefits and required investments. It also includes an introduction to the rest of the guidebook chapters, organized using the steps for installing and applying signal performance measures. While there are many signal performance measures available, this guidebook focuses on automated traffic signal performance measures (ATSPMs) developed using high-resolution controller data. ATSPMs allow an agency to continuously monitor maintenance and operations at traffic signals with a high degree of granularity because events are recorded up to 10 times every second. Most of the information in this document is directed at engineers and managers, but there is guidance throughout about how to share data with other agency groups, as signal performance measures can also enhance day-to-day activities for them. This document provides guidance under the assumption that a practitioner has basic knowledge of traffic signal systems. For more information about traffic signals and a glossary of terms, refer to NCHRP Report 812: Signal Timing Manual, 2nd Ed. (STM2) (Urbanik et al. 2015). 1.1 SIGNAL PERFORMANCE MEASURE BASICS Signal retiming projects have traditionally been triggered when a manager assigns an intersection or corridor to an engineer for retiming based on a pre-determined schedule or public service request. The engineer collects counts and observes operations in the field, builds a model to try to reflect those conditions, and adjusts the signal timing to improve operations in the model. Staff deploy the signal timing in the field, make additional adjustments based on field observations, and potentially complete a before-and-after study to document impacts. The traditional signal retiming process limits an engineer’s perspective on traffic conditions to a few days of data and field observations. While some aspects of this process will continue to be important (e.g., field observations), signal performance measures have the distinct benefit of efficiency because staff have access to comprehensive data. EXHIBIT 1-1 illustrates the basic flow of information to produce ATSPMs. Signal state (i.e., green, yellow, red) and detector events originate at an intersection and are recorded by a data logger. The logs are transferred to data storage (either server- or cloud-based), where the data can be processed by ATSPM software into a variety of reports. SIGNAL PERFORMANCE MEASURES report cycle-by- cycle events that can provide automated information for all aspects of traffic signal planning, design, and implementation through better-informed, data-driven decisions as part of a performance-based management approach. AUTOMATED TRAFFIC SIGNAL PERFORMANCE MEASURES (ATSPMs) are developed using high-resolution controller data allowing for continuous monitoring of traffic flow and traffic signal operations with a high degree of granularity because events are recorded up to 10 times every second. 4 PERFORMANCE-BASED MANAGEMENT OF TRAFFIC SIGNALS

EXHIBIT 1-1. FLOW OF INFORMATION ATSPM reports are an essential part of a modern retiming process because they are used at every step – identifying when changes are needed, informing which parameters need to change and by how much, verifying that the changes had a positive impact, and reporting results. EXHIBIT 1-2 illustrates the different steps involved in traditional and ATSPM signal retiming. Performance-based management is different from traditional retiming because staff can use ATSPMs to continuously, proactively monitor the traffic signal system instead of making periodic, reactive adjustments. EXHIBIT 1-2. TRADITIONAL VERSUS PERFORMANCE-BASED SIGNAL TIMING PROCESS SIGNAL STATE AND DETECTOR EVENTS ST M 2 ST E P S TR A D IT IO N A L A T SP M s DATA LOGGER DATA STORAGE SOFTWARE ATSPM REPORTS Trigger Event Implement Identify Desired Outcomes Monitor Develop New Signal Timing Document Public Service Request or Periodic Retiming Program Signal Timing in Controller Field Observations Counts Model Static Before/After Study Field Observations Automated Alert Program Signal Timing in Controller Review ATSPM Reports Determine Adjustments Using ATSPM Reports Dynamic ATSPM Reports Review ATSPM Reports ROADMAP TO PERFORMANCE MEASURES 5

EXHIBIT 1-3. SIGNAL PERFORMANCE MEASURE BENEFITS SOLVE PROBLEMS FASTER AUTOMATE ALERTS FOR PROACTIVE MANAGEMENT REDUCE MODELING NEEDS FOR EXISTING CONDITIONS IDENTIFY HIGH-PRIORITY LOCATIONS TRACK PROGRESS TOWARD AGENCY GOALS PRODUCE SHARABLE REPORTS THAT SUMMARIZE IMPACTS 1.2 SIGNAL PERFORMANCE MEASURE BENEFITS Using ATSPMs is a proactive approach to traffic signal system management because trends are monitored over time, allowing staff to identify issues before the public calls to report them. If public service requests are received, staff can use ATSPMs to quickly verify the information and troubleshoot issues without spending considerable time monitoring the intersection in the field. Real- time data can be used to determine impacts of signal timing changes and if additional adjustments are required. Some of the most impactful benefits are summarized in EXHIBIT 1-3. EXHIBIT 1-4 summarizes the unique roles, objectives, and benefits for each stakeholder group involved in the implementation of signal performance measures. 6 PERFORMANCE-BASED MANAGEMENT OF TRAFFIC SIGNALS

EXHIBIT 1-4. STAKEHOLDER ROLES, OBJECTIVES, AND SIGNAL PERFORMANCE MEASURE BENEFITS ROLE(S) in the management, operation, and use of the transportation system.STAKEHOLDER(S) OBJECTIVE(S) related to traffic signal operations. BENEFIT(S) achieved through the use of signal performance measures over traditional methods. Traffic Signal Engineers/ Technicians • Identify malfunctioning equipment • Adjust signal timing • Troubleshoot, validate, and address public service requests • Maximize functioning equipment • Minimize delay for transportation system users • Improve safety • Improve progression • Manage traffic variability • Continuously available metrics • Less modeling required • Automated alerts for maintenance and operational issues Traffic Signal Managers • Prioritize project locations for infrastructure improvements and signal retiming • Set agency policies and standard practices • Report to decision- makers • Acquire necessary staff and equipment resources • Allocate resources effectively • Comparable metrics across intersections and corridors for prioritizing activities • Sharable reports that summarize the impacts of maintenance and operational activities Policy Decision- Makers • Identify funding sources and determine allocation • Report to the public • Maximize investments • Quantitative performance tracking • Real-time updates IT Staff • Procure and install equipment/software • Ensure security and backups • Manage servers and databases • Install a system that is sustainable • Keep the technology functioning • Potential new role in the signal system group Other Agency Staff • Perform transportation planning • Execute design and construction • Program future transportation projects • Design and build functional traffic signals • Minimize delay during construction • Continuously available metrics • Benefit/cost information Public • Use transportation system • Provide input on performance • Reach destination in a safe and timely manner • Improved mobility • Improved reliability • Improved safety ROADMAP TO PERFORMANCE MEASURES 7

1.3 INVESTING IN SIGNAL PERFORMANCE MEASURES The building blocks for performance-based management are people and equipment. Knowledgeable staff are needed to deploy and apply signal performance measures, and collecting and calculating signal performance measures requires specialized equipment. These are the key areas where an agency needs to invest to establish a scalable, sustainable system for measuring performance. 1.3.1 PEOPLE Transitioning to performance-based management has many benefits, but it requires funding and staff resources. If an agency has champions in decision-making roles, they may be able to directly allocate budget and prioritize staff time. With that level of commitment to managing the traffic signal system, a program can function at a high level even when key staff depart. Champions are not always at the senior- management level, however, so EXHIBIT 1-5 summarizes activities that staff at all levels can undertake to support the integration of signal performance measures. It is important for an agency to gain support and cultivate champions at all levels when transitioning to performance-based management. EXHIBIT 1-5. ACTIVITIES THAT SUPPORT SIGNAL PERFORMANCE MEASURES BY STAFF LEVEL STAFF LEVEL RELATIONSHIP TO SIGNAL PERFORMANCE MEASURES ACTIVITIES THAT SUPPORT SIGNAL PERFORMANCE MEASURES Senior Management • Define agency policies • Make data-supported decisions • Clearly define staff roles and responsibilities when establishing a performance-based program • Promote use of performance measures to improve signal system management practices Mid-Level Management • Report high-level outcomes to senior management • Communicate technical details to staff • Use projects to show staff, advisory groups, citizens, and policymakers how signal performance measures can promote the mission, goals, and objectives of the agency Staff (i.e., Engineers, Technicians, Planners) • Work directly with the data and outcomes from signal performance measures • Support choices that will make signal performance measures a viable option in the future • Educate managers about the benefits of performance-based management for more effective and productive investments 8 PERFORMANCE-BASED MANAGEMENT OF TRAFFIC SIGNALS

1.3.2 EQUIPMENT AND SOFTWARE Physical equipment and software are required to collect data and process signal performance measures. An important step in implementing signal performance measures is taking stock of existing equipment and determining the degree to which it is ready for ATSPMs. The main components required for signal performance measures include: Communication Detection Data Logging Devices (i.e., Controllers) Data Storage (i.e., Server) Software Communication and detection are not required for a traffic signal to function, but they are critical to signal performance measures. Communication connects the various physical components for remote access, and detection provides information about the arrival and departure characteristics of transportation system users relative to the signal state (i.e., green, yellow, red). There are several options available for data collection devices, data storage devices, and software through vendors and open source platforms. Each system has different implementation costs, maintenance costs, features, and customization options. 1.4 IMPLEMENTING SIGNAL PERFORMANCE MEASURES The remaining chapters in this guidebook provide a path to integrate signal performance measures into the management of a traffic signal system once an agency has decided to implement them. The eight basic steps are summarized in EXHIBIT 1-6. Additional details are provided throughout the chapters as shown. EXHIBIT 1-6. ROADMAP FOR IMPLEMENTING SIGNAL PERFORMANCE MEASURES 1 SELECT PERFORMANCE MEASURES CHAPTERS 2 + 3 2 DETERMINE IMPLEMENTATION SCALE 3 CONDUCT SYSTEM NEEDS GAP ASSESSMENT CHAPTER 4 4 PROCURE RESOURCES 5 CONFIGURE SYSTEM CHAPTER 56 VERIFY SYSTEM 7 APPLY PERFORMANCE MEASURES 8 INTEGRATE INTO AGENCY PRACTICE CHAPTER 6 ROADMAP TO PERFORMANCE MEASURES 9

STEP 1: SELECT PERFORMANCE MEASURES The first step in establishing a performance- based program is determining which signal performance measures are the most important. The answer will depend on agency goals, objectives, and methods of signal system management. Although an agency may be capable of producing many signal performance measures, it is helpful to identify the key measures for decision- making to avoid overwhelming staff with data. Chapter 2 outlines the recommended process for selecting signal performance measures based on signal system objectives, which is similar to the outcome-based process introduced in the STM2 (Urbanik et al. 2015). Detailed descriptions of each performance measure are provided in Chapter 3. STEP 2: DETERMINE IMPLEMENTATION SCALE Some agencies may choose to implement signal performance measures across their entire system in a single effort. However, most agencies will use an incremental approach, deploying small-scale pilot projects or upgrading equipment as part of programmed projects or an existing maintenance program. Chapter 2 summarizes how an agency should assess and plan the implementation scope. STEP 3: CONDUCT SYSTEM NEEDS GAP ASSESSMENT Once performance measures and intersections have been selected, an agency should conduct a gap assessment to determine if any changes to equipment, business processes, organizational structure, or resources are required. Chapter 4 provides guidance on conducting a gap assessment and shows how the results may influence what performance measures are ultimately implemented. STEP 4: PROCURE RESOURCES The results of the gap assessment will identify additional resources necessary for a successful deployment and long-term operations and maintenance. Chapter 4 provides guidance on acquiring equipment and staff, including coordination with other jurisdictions. ATSPMs are a critical step on the road to smart communities and connected people, so Chapter 4 also includes procurement considerations related to future technologies. STEP 5: CONFIGURE SYSTEM Deployment involves activities at the intersection and system level. The equipment and software used to collect, store, and process data from the traffic signals will need to be configured, and information for each intersection will need to be programmed. Chapter 5 describes the typical process an agency will use to configure hardware and software. STEP 6: VERIFY SYSTEM Once the system has been installed, a verification process should be undertaken to ensure that data is being collected consistently with an acceptable degree of precision and that performance measures are being calculated correctly. External data from separate sensor networks or special field studies may be useful in this step. Chapter 5 provides a number of strategies to verify that performance measures match field conditions. 1 4 5 6 2 3 10 PERFORMANCE-BASED MANAGEMENT OF TRAFFIC SIGNALS

STEP 7: APPLY PERFORMANCE MEASURES Signal performance measures can be used to inform signal timing adjustments, identify mis-programmed signal timing parameters (e.g., values that were initially programmed incorrectly), and identify equipment that is malfunctioning. Chapter 5 uses examples to demonstrate how an agency can apply different ATSPMs for effective management of the traffic signal system. STEP 8: INTEGRATE INTO AGENCY PRACTICE By integrating signal performance measures into day-to-day practice, an agency will have continuous monitoring capabilities. Further, developing a record of performance will enable an agency to be better informed about the effectiveness of maintenance and operations practices and where to invest funding and staff resources. Chapter 6 describes how to incorporate performance-based management into agency policies and how signal performance measures may change day-to-day practices for various stakeholders. 1.5 REFERENCE 1. Urbanik, T., et al. 2015. NCHRP Report 812: Signal Timing Manual, 2nd Ed. Transportation Research Board of the National Academies, Washington, DC. 7 8 ROADMAP TO PERFORMANCE MEASURES 11

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Performance-Based Management of Traffic Signals Get This Book
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Management of traffic signal systems is a critical function for many transportation agencies. Thanks to advancements in technology, it is now possible to collect large amounts of data at signalized intersections, leading to the development of dozens of performance measures.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 954: Performance-Based Management of Traffic Signals provides information to help agencies invest in signal performance measures as part of a comprehensive approach to performance-based management.

Supplementary materials to the report include a data dictionary and a PowerPoint presentation.

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