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233 6.1 Introduction This chapter presents four case studies of project design processes that evaluate alterna- tives for improving the accommodation of all users (motorized and non-motorized) of a facility. In each case study, the roadways under design are primarily auto-dominated facili- ties, and the design process evaluates alternatives for balancing safety, LOS and QOS to all anticipated modes. The four design case studies are abbreviated versions of case examples originally devel- oped in other design guidance documents. To accommodate the style variations of the case studies, numbered headings extend only to second-level headings in this chapter. Case studies A and C are adapted with permission from Designing Walkable Urban Thorough- fares: A Context Sensitive Approach (ITE 2010a). The design process used in these examples is relatively simple and qualitative, but the cases provide effective examples of a thoughtful and comprehensive process for developing, evaluating and selecting solutions to design challenges. They employ a straightforward, high-level trade-off analysis for different design elements and goals. The design examples provide a general overview of the process to illustrate the five suggested stages of design in the ITE document. As summarized in this Guide, case studies A and C focus on the details of the evaluation and development of the actual design. Case studies B and D are adapted with permission from NCHRP Report 785: Performance- Based Analysis of Geometric Design of Highways and Streets (Ray et al. 2014). The design process used in these examples represents a higher order of design analysis that is intended to help users apply the concepts, models and performance evaluation framework element presented in the NCHRP report. The original case studies are based on a variety of specific projects, amalgams of projects, or project considerations that are commonly found in practice. The key project elements evaluated are emphasized to support and promote the principles of performance- based analysis of geometric design. The examples selected for case studies B and D in this Guide involve designing projects for a mix of users in common scenarios potentially faced by design practitioners. All the case study examples provide useful information to the design practitioner. They illus- trate the range of qualitative and quantitative design analysis that can be applied to a multimodal design process addressing several different roadway classifications and contexts in low- and intermediate-speed environments. The formatting of headings and text within the case studies generally reflect the presentations used in the original documents. For readersâ convenience, some minor stylistic edits have been made and exhibit numbering has been updated for consis- tency with the rest of this Guide. C H A P T E R 6 Case Studies: Designing for All Users
234 Design Guide for Low-Speed Multimodal Roadways 6.2 Design Case Study A: Creating a Retail-Oriented Main Street This design alternatives case study for creating a retail-oriented main street is taken from Designing Walkable Urban Thoroughfares: A Context Sensitive Approach (ITE 2010a). The project involves conversion of an existing four-lane collector street into a commercial-oriented street that supports typical community main street activities. Although the design case study illustrates how a designer can evaluate design alternatives in a primarily qualitative manner, elements of quantitative analysis (e.g., employing more detailed quality, capacity and safety analysis procedures) could be integrated into the design concept evaluation process. Additional information about the specific context designations mentioned in the case study can be found in the original ITE document (ITE 2010a). 6.2.1 Design Objective Convert an existing four-lane minor collector street into a commercial-oriented street that supports an adjacent mix of retail, restaurants and entertainment uses on the ground floor. Stage 1: Review or develop an Area Transportation Plan. Review the area transportation plan(s) to determine how the subject thoroughfare relates to the overall network, types of modes served, functional classification, existing and future opera- tional characteristics and so forth. Collect existing and projected data as necessary. 6.2.2 Existing Street Characteristics The existing street is a four-lane, undivided collector street with the following characteristics (see Exhibits 6-1 and 6-2). ⢠Functional classification: minor collector; ⢠Right-of-way: 60 ft.; ⢠Four through-traffic lanes plus 6-ft. sidewalks on each side; ⢠On-street parking: none; ⢠Average daily traffic (ADT): 10,000â13,000 vehicles per day (VPD); ⢠Speed limit: 35 mph; ⢠Percent heavy vehicles: 2â3 percent; ⢠Intersection spacing: 600â700 ft.; Source: ITE (2010a) Exhibit 6-1. View of existing street.
Case Studies: Designing for All Users 235 ⢠Network pattern: grid; ⢠Center turn lane: none; ⢠Transit: low-frequency local route; ⢠Bicycle facilities: not a designated bike route; ⢠No landscaping; and ⢠Conventional street and safety lighting. Stage 2: Understand community vision for context and thoroughfare. 6.2.3 Vision An existing commercial street in a suburban area undergoing change to an urban center. Emphasizes an active street life that is to be achieved through the mix and intensity of land uses, site and architectural design, with an emphasis on pedestrian facilities and on-street parking. Stage 3: Identify compatible thoroughfare types and context zones. Existing context is identified by assessing the character and attributes of existing land uses such as building orientation to the street, building height, parking orientation, mix and density of uses and so forth. Future context is determined by interpreting the vision, goals and objec- tives for the area. Note: The thoroughfare type is selected based on the set of urban thorough- fare characteristics listed in Table 4.2 in Designing Walkable Urban Thoroughfares (ITE 2010a). For brevity, the table is not reproduced in this Guide. ⢠Existing context zone: C-3 (suburban area); ⢠Future context zone: C-5 (urban center); and ⢠Desired thoroughfare type: avenue. Stage 4: Develop and test the initial thoroughfare design. 6.2.4 Desirable Design Elements Desirable design elements (ranked based on vision): ⢠Lower target speed; ⢠On-street parking; ⢠Wide sidewalks; ⢠Street furniture and landscaping including benches and space for cafes, public space and so forth; ⢠Pedestrian-scaled lighting; ⢠Street trees; ⢠Bus stops with shelters; ⢠Transitions between main street and adjacent higher-volume segments; ⢠Mid-block crosswalks on long block sections; and ⢠Bicycle accommodations. Source: ITE (2010a) Exhibit 6-2. Existing street cross section.
236 Design Guide for Low-Speed Multimodal Roadways 6.2.5 Factors to Consider/Potential Trade-Offs Factors to consider/potential trade-offs are: ⢠Right-of-way constrained to 60 ft.; ⢠Maximized parking using angled versus parallel parking (although change to angled parking may increase accidents and delays); ⢠Reduction in the number of through lanes and vehicle capacity versus wider sidewalks and on-street parking; ⢠Accommodation of large vehicles versus narrowing lane width and smaller curb-return radii to reduce pedestrian crossings; and ⢠Accommodation of bicyclists versus width of other design elements. 6.2.6 Possible Alternative Solutions Possible alternative solutions (see Exhibit 6-3) are: 1. Emphasize vehicular capacity by retaining existing four-lane section with 10-ft.-wide travel lanes to allow 10-ft.-wide sidewalks; 2. Emphasize parking by providing angled parking on one side, parallel parking on the other side and narrowing the two remaining travel lanes; 3. Emphasize parking and wider sidewalks by providing parallel parking on both sides, two travel lanes and 12-ft.-wide sidewalks; or Source: ITE (2010a), Figure 6-12 Exhibit 6-3. Alternative street cross sections.
Case Studies: Designing for All Users 237 4. Emphasize parking and vehicular capacity with parallel parking on both sides, 9-ft.-wide sidewalks, two travel lanes and a center turn lane. In all cases, use a grid network to divert some traffic from project thoroughfare so a reduced number of traffic lanes will suffice. This approach may require operational or physical improve- ments to other streets. Traffic to be diverted will depend on travel patterns, context and design of other thoroughfares. Compare the benefits of the alternatives. Exhibit 6-4 demonstrates one way of showing such a comparison. 6.2.7 Selected Solution This alternative: ⢠Maximizes sidewalk width; ⢠Provides moderate to good level of on-street parking; ⢠Balances street width with accommodation of larger vehicles and speed reduction; ⢠Allows for left-turn lanes at intersections by restricting parking; and ⢠Provides 10-ft. minimum travel lane width. Stage 5: Develop a detailed thoroughfare design. Exhibit 6-5 shows a rough schematic view of how the selected alternative might be designed. 6.2.8 Solution Design Features Traveled Way: ⢠Target speed: 25 mph; ⢠Traffic signals synchronized to target speed; ⢠Two 10-ft. travel lanes; and ⢠Two 8-ft. parallel parking lanes. Source: ITE (2010a) Exhibit 6-4. Relative comparison of alternative trade-offs.
238 Design Guide for Low-Speed Multimodal Roadways Streetside: ⢠12-ft. sidewalks; ⢠Pedestrian-scaled lighting; ⢠Street trees in tree wells; ⢠6-ft. furnishings and edge zone; ⢠6-ft. clear pedestrian throughway; and ⢠No frontage zone. Intersections: ⢠Curb extensions to reduce pedestrian crossing distance unless left-turn lane is provided; ⢠High-visibility crosswalk markings; ⢠Safety lighting; ⢠Far-side bus stops with curb extension and shelters; and ⢠ADA compliance. Source: ITE (2010a) Exhibit 6-5. Schematic plan view of Alternative 3.
Case Studies: Designing for All Users 239 Parallel Thoroughfares (as needed): ⢠Directional signing; ⢠Operational adjustments or improvements; and ⢠Physical improvements. 6.3 Design Case Study B: Cascade Avenue The design alternatives case study for Cascade Avenue is taken from NCHRP Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets (Ray et al. 2014). This project involved reconstruction of an existing urban arterial with the goal of integrating new âcomplete streetsâ elements into the corridor project to better accommodate multiple modes and support improvements to community livability and increased economic activity. This case study illustrates how the performance-based analysis suggested by NCHRP Report 785 can be incorporated into the design concept development process. It also dem- onstrates the complicated nature of evaluating and interpreting results for several alternatives across multiple modes using a variety of performance measures. For a more detailed version of this case study that includes the report authorâs notes, see NCHRP Report 785. This project example illustrates how performance-based analysis can be integrated into recon- structing an existing auto-oriented urban arterial to incorporate complete street attributes with a focus on alternative street cross sections. In this project example, the project is initiated and championed by local business owners (i.e., local business improvement district) who would like to see the corridor revitalized in terms of the local economy and broader community livability. The learning objectives of this project example include the following: ⢠Incorporate performance measures and decisions related to accommodating multiple modes; ⢠Illustrate trade-offs between modes considering measures beyond mobility; and ⢠Capture considerations and trade-offs within a constrained physical environment. The broader project objectives (i.e., increase economic vitality and community livability) are connected to geometric design performance categories of QOS for multiple modes, safety, access, reliability and mobility. 6.3.1 Project Initiation Project Context The following summary of the project context sets the foundation for the remaining activi- ties within the performance-based analysis framework. An important factor in the context of this project example is that the motivation for the project is being driven both by members of the local business community, who would like to see the corridor revitalized from an economic standpoint, and by the perspective of long-term livability for the surrounding community. The local business community lobbied city staff and decision makers to study and implement design solutions to Cascade Avenue. The intended project outcome is to make it a more com- fortable, safe and attractive urban street for transit riders, pedestrians and bicyclists. Cascade Avenue is an urban arterial providing a north-south connection between the downtown district and a university campus approximately 2 miles north of downtown. It is currently a four-lane undivided arterial with on-street parallel parking and intermittent transit stops. Under the exist- ing condition, there are no bicycle lanes and sidewalks are curb-tight (i.e., no landscape buffer exists between the sidewalk and roadway).
240 Design Guide for Low-Speed Multimodal Roadways The AADT volume for Cascade Avenue is 22,000 VPD. It is a key arterial for three different fixed transit routes serving approximately 45 percent of the transit riders traveling within the city. Despite the lack of bicycle facilities on Cascade Avenue, it is already a frequently used route by bicyclists traveling between downtown and the university campus, as it is the most direct route between those two origins-destinations. The posted speed on Cascade Avenue is 35 mph. Local law enforcement has a difficult time enforcing the posted speed during off-peak periods when traffic is relatively low. The higher speeds in off-peak travel periods make Cascade Avenue less attractive to pedestrians and bicyclists. The local business community would like Cascade Avenue to become a more well-rounded city street. They would like people in the surrounding communities to see and use it as a place to spend time, visit shops, linger at cafes and restaurants, as well as use it to travel within the city. The business communityâs overarching motivation for the project is to revitalize Cascade Avenue and the surrounding area economically. They see improvements to Cascade Avenue from an urban design and transportation perspective as critical to their mission. The city agreed to study the street to identify and evaluate a range of potential configurations to better serve multiple modes and create a more complete urban street environment. This project example documents the preliminary design development and evaluation of alter- native street cross sections. The primary condition requested by local business owners is to keep the potential solutions on Cascade Avenue within the existing 82-ft.-wide right-of-way. The business community is open to removing the existing on-street parking as a means to provide more space for other modes or uses. They are also in the process of gaining support from a broad base of local business owners to form a local improvement district (LID) to help fund the project. 6.3.2 Intended Project Outcomes The project example summarizes the key information related to stakeholders the project is intended to serve, what the project is intended to achieve (i.e., intended project outcome), the applicable project performance category (or categories), and the applicable performance measures. In this project example, the project purpose is to enhance the multimodal characteristics of Cascade Avenue in support of the local business improvement district that would like to have more pedestrian activity along the corridor as a means for revitalizing the surrounding com- munity. There are no direct geometric performance measures for evaluating how well a proj- ect alternative will revitalize or facilitate economic or community growth. However, there are indirect geometric performance measures contributing to characteristics that would support economic and/or community revitalization (e.g., QOS for pedestrians, bicyclists and transit riders). In this project example, safety, mobility, QOS, accessibility and reliability are the geo- metric performance categories contributing to the broader goal of improving economic vitality along the corridor. The local business community is the champion for the project. They are the catalyst for identifying and implementing a project on Cascade Avenue with the purpose of revitalizing the street and surrounding areas from an economic and livability perspective. The primary target audience is the business community stakeholders who would like to see transit riders, pedestrians and bicyclists better served by Cascade Avenue. As a result, transit riders, pedestri- ans and bicyclists are key road users served by the project. Secondary target audiences include local residents and existing motorists. The project will need to balance the impacts on existing
Case Studies: Designing for All Users 241 automobile and transit service. The key agency stakeholders are the city and local transit agency. The city has jurisdictional responsibility over Cascade Avenue. Therefore, it will be responsible for capital improvements, maintenance and operations of the street. The local transit agency currently has three of its major fixed-route bus routes using Cascade Avenue to serve a large portion of its ridership. The intent of the study is to improve the road user experience and provide access for road users not previously served while enhancing the economic vitality and activity of the street. The performance categories selected are QOS, safety, accessibility, reliability and mobility. The performance measures to be used to evaluate alternative roadway cross sections are: ⢠QOS (MMLOS from the HCM (TRB 2010); ⢠Safety (crash frequency and number and management of conflict points); ⢠Accessibility (type and presence of facilities and transit service characteristics); ⢠Mobility (average travel time); and ⢠Reliability (consistency in travel time). These performance measures do not directly measure economic vitality for an area or the potential for economic vitality. However, they are connected to geometric character- istics and reflect characteristics influencing different road usersâ quality of experience. For example, a better MMLOS grade for the pedestrian mode corresponds to roadway geometric characteristics more likely to create an attractive environment in which pedestrians feel safe and comfortable. This helps achieve the business communityâs goal of transforming Cascade Avenue into a city street where people want to shop, dine, and generally spend time. Similar parallels can be drawn for the other performance measures listed. 6.3.3 Concept Development Geometric Influences Roadway cross-sectional elements were selected as the primary geometric elements likely to influence the performance measures associated with: ⢠Lane width; ⢠Number of automobile through lanes; ⢠Bicycle facility presence and type (e.g., bicycle lanes, buffered bicycle lanes); ⢠Sidewalk width; ⢠Presence and width of landscaped buffer between sidewalk and travel lanes; ⢠Presence and type of on-street parking (e.g., parallel parking, angled parking); ⢠Bus-only lanes; and ⢠Central roadway median. The potential solutions explore different combinations of cross-section characteristics and create a range of alternatives reflecting the trade-offs inherent in trying to serve different travel modes within a constrained right-of-way. 6.3.4 Potential Solutions The primary constraint and challenge in developing solutions for Cascade Avenue is serv- ing the range of existing and desired road users within the existing right-of-way. Automobiles are currently given the majority of space on Cascade Avenue; therefore, additional alternatives developed for Cascade Avenue are oriented toward one or more combinations of better serving
242 Design Guide for Low-Speed Multimodal Roadways transit riders, pedestrians, and bicyclists. The four basic alternatives (including the existing condition) are: ⢠Basic Alternative 1: Existing cross section oriented toward serving automobiles; ⢠Basic Alternative 2: Transit-oriented cross section; ⢠Basic Alternative 3: Bicycle- and pedestrian-oriented cross section; and ⢠Basic Alternative 4: Hybrid of transit, bicycle, and pedestrian features. Alternative 1 will serve as a common baseline for comparison across alternatives; it is the existing roadway that prioritizes space for automobiles. Alternative 2 focuses on serving transit vehicles and riders. The roadway features within Alternative 2 include elements such as transit- only lanes. Alternative 3 is oriented toward bicycle and pedestrian modes and includes features such as buffered bicycle lanes. Alternative 4 is a hybrid of alternatives 2 and 3. It strives to balance the needs of transit riders, bicyclists, and pedestrians. ⢠Resources used to develop solutions. The project team used the Urban Street Design Guide (NACTO 2013) as a resource for developing alternative cross sections. The team also used NACTOâs Urban Bikeway Design Guide (NACTO 2014) and AASHTOâs Guide for the Devel- opment of Bicycle Facilities, 4th Ed. (AASHTO 2014b) in identifying and developing alter- natives. They used these guidance documents in combination with the cityâs local design guides and standards. The resources were particularly helpful in providing visuals, examples, and alternative approaches for addressing the challenge of serving multiple travel modes. This project example focuses on documenting the development, analysis, and selection of a new, basic cross section for Cascade Avenue. There is valuable information in these reference materials regarding design and operational strategies for managing conflicts between modes at intersections and within the transition areas influencing how well an overall street corridor serves road users. ⢠Solution development. Each alternative cross section has a modal emphasis in contrast to the existing auto-oriented cross section. The cross-section alternatives were developed to be reasonable representations of a type of alternative. This means some design details (such as curb type) will be determined in later stages of project development. A common element among the alternatives is the lack of on-street parking. The local busi- ness community expressed interest in increasing pedestrian activity on the street and there- fore the desire to focus on solutions providing more space for that activity. This approach is consistent with the broader cityâs goals and policies to focus on projects serving person- trips rather than auto-only trips. This translates to creating more space for modes other than autos. The primary concern related to eliminating on-street parking on Cascade Avenue was that vehicles would use on-street parking in adjacent residential areas. The city is address- ing this concern as part of a broader citywide parking management plan encompassing the Cascade Avenue area as well as the downtown district and the area surrounding the university. Other trade-offs considered by the project team while developing and identifying the spe- cific characteristics within each cross section included allocating lanes for specific modes. For example, providing a transit-only lane has the ability to improve mobility and reliability for transit riders by reducing the average travel time along the corridor for transit riders. This option also provides more predictable operating conditions for transit vehicles in peak traffic conditions. Allocating space to transit vehicles negatively impacts mobility (and potentially reliability) for automobiles, however, because they are reduced to one lane in each direction of travel instead of the existing two lanes. Similar trade-offs were considered related to pro- viding bicycle lanes and wider sidewalks for pedestrians. Another characteristic reflected in two of the alternatives is adding a central landscaped median that would transform Cascade Avenue to a divided facility. There are documented safety benefits for autos and pedestrians in having a median. A median also provides space
Case Studies: Designing for All Users 243 to implement landscaping to help improve the aesthetics of the corridor. As will be seen in Alternative 3, the project team also considered changes that would provide additional desig- nated space for pedestrians and bicyclists and create a buffer between pedestrians and bicy- clists and moving vehicles. The intent of these features is to decrease the likelihood of crashes and improve the overall experience of traveling and spending time on Cascade Avenue. 6.3.5 Primary Alternatives for Evaluation Using the resources and considerations previously described in brief, the project team arrived at the following alternatives for evaluation: ⢠Alternative 1 (Existing, Auto Oriented): Four-lane undivided roadway with on-street parallel parking on both sides of the street (see Exhibit 6-6); ⢠Alternative 2 (Transit Oriented): Four-lane divided roadway with transit-only lanes and increased sidewalk widths (see Exhibit 6-7); ⢠Alternative 3 (Bicycle and Pedestrian Oriented): Two-lane divided roadway with a buff- ered bicycle lane, landscaped buffer, wider sidewalks, and shared auto-transit lane (see Exhibit 6-8); and ⢠Alternative 4 (Hybrid of Transit, Bicycle and Pedestrian Alternatives): Four-lane undivided roadway with transit-only lanes, bicycle lanes, and a wider sidewalk (see Exhibit 6-9). The exhibits illustrate common elements among the alternatives. For example, the alternatives: ⢠Fall within the existing 82-ft. of right-of-way width and, therefore, do not require additional right-of-way; ⢠Require changing the existing curb locations and, therefore, revising stormwater management and drainage along the corridor; Exhibit 6-6. Cross section of existing roadway. Exhibit 6-7. Transit-oriented roadway cross section.
244 Design Guide for Low-Speed Multimodal Roadways ⢠Reduce the capacity for automobiles from two lanes in each direction to one lane in each direction; ⢠Remove on-street parking (as discussed previously); and ⢠Increase sidewalk width for pedestrians. The differentiating factors across the alternatives that influence their performance include the amount of space designated for bicyclists, presence of a central median, the presence of a physical buffer for pedestrians and bicyclists from motorized vehicles, and the type of space allocated for transit vehicles. Additional critical issues that are not directly captured in the exhibits but that will need to be considered prior to selecting an alternative for implementation include the following: ⢠Logistics (e.g., allocating designated zones) of truck loading and unloading for the businesses along Cascade Avenue; ⢠Definition of transition areas on approach to intersections or major driveways where vehi- cle turning movements will occur; these conflict areas will need to be managed particularly within alternatives providing transit-only and/or bicycle lanes; and ⢠Revisiting, confirmation, and possibly modification of intersection control, lane configu- rations, and/or signal timing (if a signal is present) to better align with the selected cross section. For example, if Alternative 2, the transit-oriented cross section, is selected, the city may want to implement transit signal priority to help maintain consistent and reliable transit ser- vice along the corridor. These additional considerations are not addressed within this project example but are considered in the broader context of implementing the selected cross-sectional alternative. Exhibit 6-8. Bicycle- and pedestrian-oriented roadway cross section. Exhibit 6-9. Hybrid of transit, pedestrian and bicycle alternatives.
Case Studies: Designing for All Users 245 6.3.6 Evaluation and Selection The performance categories evaluated for this project focus on the following: ⢠Safety, as defined by crash frequency, crash severity and conflict points; ⢠Mobility, as defined by average travel time; ⢠Reliability, as defined by variation in travel time; ⢠Accessibility, as defined by type and facility presence and transit service characteristics; and ⢠QOS, as defined by MMLOS. To the extent feasible, the project team estimated the performance of each alternative quanti- tatively. However, in some cases, due to the state of the research and practice, a qualitative assess- ment was necessary. Exhibit 6-10 summarizes the resources used to calculate the performance of each alternative. The NCHRP Report 785 project team faced several challenges in being able to assess each alternative quantitatively across the full range of selected categories and associated performance measures. The primary challenge reflected gaps in the available research findings. For example, these gaps impeded efforts to quantify the performance of all of the innovative street cross sec- tions being considered for Cascade Avenue. This section provides more detailed descriptions of how each resource can be used to estimate the performance measures identified under the âIntended Project Outcomes.â The descriptions include instances when a qualitative assessment was necessary. ⢠Safety. The methodologies and information in AASHTOâs HSM can be used to estimate the predicted safety performance for roadway cross sections of urban/suburban arterials. The HSM addresses cross sections ranging from two-lane undivided to five lanes (a five-lane cross section has two lanes in each direction with a two-way center turn lane). Therefore, the HSM can be used to estimate the long-term annual safety performance of Cascade Avenue under existing conditions. However, the remaining alternatives include cross-sectional features that cannot be evaluated using the HSM or another known resource: â The transit lanes present in Alternatives 2 and 4, â The buffered bicycle lane present in Alternative 3, and â The traditional bicycle lane in Alternative 4. Therefore, the relative safety performance of these alternatives was considered qualitatively based on their abilities to separate conflicting modes and provide additional and/or protected space for vulnerable users (i.e., pedestrians and bicyclists). ⢠Mobility. The project team used a software program to implement HCM 2010 methodolo- gies (TRB 2010) and estimate the average travel time from one end of Cascade Avenue to the other. The average travel time was estimated for the morning, midday, and evening weekday Alternative Safety Mobility Reliability Accessibility QOS 1: Existing Condition HSM, Chapter 12 HCM 2010 HCM 2010 Qualitative Assessment HCM 2010 2: Transit Oriented HSM, Chapter 12 Principles HCM 2010 HCM 2010 Qualitative Assessment HCM 2010 3: Bicycle and Pedestrian Oriented HSM, Chapter 12 Principles HCM 2010 HCM 2010 Qualitative Assessment HCM 2010 4: Hybrid of Transit, Bicycle, & Pedestrian HSM, Chapter 12 Principles HCM 2010 HCM 2010 Qualitative Assessment HCM 2010 Resource references: HSM (AASHTO 2010), HCM 2010 (TRB 2010) Source: Ray et al. (2014) Exhibit 6-10. Summary of resources for performance evaluation.
246 Design Guide for Low-Speed Multimodal Roadways periods, as well as the Saturday midday peak period. The intent of including multiple periods was to obtain a sense of the range of travel time during low-, mid-, and high-traffic volume periods. The analysis focused on average travel time for motorists and transit vehicles (and, therefore, transit riders). ⢠Reliability. Research is ongoing within the transportation profession to develop performance measures and a means to strengthen the connection between reliability and geometric design decisions. In the context of urban arterials, measuring the variation in travel time is the best means for estimating relative consistency for motorists and transit riders on Cascade Avenue. To estimate the potential variation in travel time, the project team simulated traffic operations along the corridor for different periods of the day to reflect different traffic volume demands and introduced different unanticipated events (e.g., partial or full lane closure due to a crash or truck loading/unloading) to estimate the relative consistency in travel time for each alter- native. The analysis focused on the variation in travel time for auto and transit vehicles. As will be seen in the results discussed later, providing a transit-only lane can notably help improve reliability for transit vehicles and riders. Results only speak to the reliability of the transit routes while they are traveling on Cascade Avenue; events may occur prior to or after the routes depart Cascade Avenue that negatively impact their overall reliability. ⢠Accessibility. The project team evaluated access qualitatively, giving it an assessment of low, moderate or high depending on the presence of facilities for specific modes and the transit service characteristics reflected in each alternative. Within this project context, additional access to the corridor for pedestrians, bicyclists, and transit riders was considered a positive performance characteristic given the overarching goal of the project to increase economic vitality of the corridor through increased pedestrian activity or person-trips. ⢠QOS. MMLOS was calculated using the methodology presented in the HCM 2010 (TRB 2010). The methodology produces a letter grade (A through F) to indicate the quality of the travel experience from specific road usersâ perspectives. Therefore, it is possible for the same alterna- tive to produce a LOS C for bicyclists and LOS B for pedestrians. In other words, the methodol- ogy reflects that one street cross section can result in different qualities of experience depending on whether a person is walking, biking, taking transit or driving an automobile. It is a useful methodology, particularly in combination with the HSM, because MMLOS captures some of the benefits from project elements the HSM cannot, such as bicycle lanes. The results of the performance analysis are summarized in Exhibit 6-11. The results for the safety and access evaluations are categorized as low, moderate or high. In the context of this project, high performance in those two categories is desirable. High safety performance means, in a qualitative assessment, there is a lower likelihood of crashes and/or severe crashes due to attributes such as separate designated space for vulnerable modes, physical separation of vulnerable modes from motorized vehicles, and other similar attributes. Exhibit 6-11 demonstrates that it can be a complicated exercise to evaluate and interpret results from the evaluation of several alternatives across multiple modes using a variety of per- formance measures. Key themes the project team identified from the performance evaluation results included the following: ⢠Safety. Alternatives 2 and 3 are expected to have better safety performance compared to other alternatives. This is attributable to the presence of the central median. The median separates vehicles moving in the opposite direction and provides a pedestrian refuge for pedestrian cross- ings at intersections and mid-block. These alternatives also include separate facilities designated for auto, transit and bicycles. Furthermore, Alternative 3 includes additional buffering for pedes- trians and bicyclists from motorized traffic. As noted previously, if Alternative 2 or 3 is selected (or if Alternative 4 is selected), the project team will need to spend time designing transition areas to transition from the street cross section to intersections where vehicle turn movements will need to occur. Within Alternative 3, the team will also need to consider and develop an approach
Case Studies: Designing for All Users 247 for managing conflicts between transit vehicles and bicyclists on approach to transit stops. This may include strategies such as moving the transit stop to a platform away from the sidewalk and having the bicycle lane pass between the platform and the sidewalk. Alternatives 1 and 4 have the lowest expected safety performance. This is attributed to the lack of a central median and, in the case of Alternative 1, the lack of separate facilities for bicyclists and transit vehicles. ⢠Mobility. Alternative 1 is expected to have the highest mobility (i.e., lowest average travel time) for motorists on Cascade Avenue, which is attributed to the four-lane cross section. Alternatives 2 and 4 are the next two alternatives with higher mobility for motorists and tran- sit vehicles. Each of these alternatives includes a transit and auto lane in each direction and, therefore, has similar mobility results for those modes. The average travel time reflected in alternatives 2 and 4 is closer to the posted speed limit on Cascade Avenue of 35 mph, which is desirable with respect to safety (i.e., it provides more time for motorists to react to roadway conditions and is more likely to result in less severe crashes in the event one occurs) and creat- ing a more comfortable environment for pedestrians and bicyclists. ⢠Reliability. Alternatives 2 and 4 have the highest reliability (i.e., lowest variation in travel time) for transit riders and motorists. While these two alternatives do not have the highest mobility for motorists, they do create moderately more consistent travel times. Increased reliability is achieved primarily by the transit lanes included within the alternatives. Transit lanes prevent 1 â Existing Condition Pedestrian Low â â Low D Bicycle Low â â Low F Transit Low 4.43 3.68 to 5.26 Moderate D Auto Low 2.67 2.42 to 3.17 High A 2 â Transit Oriented Pedestrian High â â Moderate C Bicycle Moderate â â Moderate E Transit High 4.40 3.68 to 4.76 High B Auto High 3.43 3.35 to 3.60 Low C 3 â Bicycle and Pedestrian Oriented Pedestrian High â â High B Bicycle High â â High C Transit High 4.80 3.97 to 6.00 Moderate D Auto High 4.80 3.80 to 6.10 Low D 4 â Hybrid of Transit, Bicycle and Pedestrian Pedestrian Low â â Moderate C Bicycle Moderate â â Moderate D Transit Moderate 4.38 3.65 to 4.78 High B Auto Low 3.45 3.32 to 3.56 Low C The exhibit summarizes results for the Saturday midday peak period. Similar summaries were prepared for the weekday evening and morning periods. â indicates not applicable. Source: Ray et al. (2014) Exhibit 6-11. Performance evaluation results.
248 Design Guide for Low-Speed Multimodal Roadways motorists from being stuck behind a transit vehicle loading and unloading passengers. The increased reliability is also attributable to removing the on-street parking present in Alter- native 1. Alternative 3 has the lowest reliability for transit riders and motorists. This is because transit vehicles and motorists are sharing a single travel lane in each direction; therefore, transit stops, truck loading and unloading maneuvers, and incidents (and incident manage- ment) directly affect the space both modes need for travel. This creates the greater variation in travel time. ⢠Accessibility. Alternatives 2, 3 and 4 provide similar levels of access for pedestrians, transit riders, bicyclists, and motorists. Within Alternatives 2, 3 and 4, access (with respect to being able to travel on Cascade Avenue and gain access to the businesses along it) ranges from moderate to high for pedestrians, transit riders and bicyclists because of the presence of facilities for those modes. Within those same alternatives, access for motorists is evaluated as low. This is primarily because on-street parking is not included in alternatives 2, 3 or 4. ⢠QOS. Alternative 3 provides the highest QOS for pedestrian and bicycle modes. The high QOS for pedestrians is attributable to the wider sidewalks, landscaping buffer and additional separa- tion from motorized vehicles gained from the adjacent buffered bicycle lane. For bicyclists, the higher QOS is attributable to eliminating on-street parking, providing a designated bicycle lane and including a wider width for the buffered bicycle lane. Alternatives 2 and 4 provide the best QOS for transit riders, which is primarily attributed to the operational benefits of the transit lanes (e.g., better service characteristics). This is in combination with the pedestrian improve- ments included in those alternatives. Motoristsâ QOS is highest in Alternative 1 because of the higher mobility and relatively few times motorists would need to stop. Motorists are expected to experience moderate QOS within alternatives 2 and 4. This is likely attributed to separating automobiles and transit vehicles to help manage the number of times motorists would need to stop while traveling the corridor. Given these considerations purely based on performance evaluation results, the project team and broader stakeholders felt Alternatives 2 and 3 had performance characteristics best reflecting the attributes they desired for Cascade Avenue. To evaluate financial feasibility, the project team developed cost estimates for each alternative. The cost estimates considered critical characteristics such as the costs of curb relocations, modi- fications needed to stormwater drainage and management, new pavement markings, revisions to signing, modifications to transit stop locations and configurations, improved illumination, and landscaping and other similar costs associated with the unique characteristics of each alternative. Exhibit 6-12 summarizes the cost estimates for the alternatives. The significant elements influ- encing cost include modifying the stormwater drainage, adding a median, landscaping, changing transit stop locations and configurations, and pavement rehabilitation. Many of these attributes are present within Alternatives 2, 3 and 4 to varying degrees. Alter- natives 2 and 3 are higher in cost than Alternative 4 because of the median and additional landscaping that they include. The NCHRP Report 785 project team did not estimate a benefit/cost ratio or calculate a cost-effectiveness factor for the alternatives. To be able to calculate a benefit/cost ratio or Alternative Cost per Mile 1: Existing Condition $0 2: Transit Oriented $1.4 million 3: Bicycle and Pedestrian Oriented $1.6 million 4: Hybrid of Transit, Bicycle and Pedestrian $1.0 million Source: Ray et al. (2014) Exhibit 6-12. Cost estimates.
Case Studies: Designing for All Users 249 cost-effectiveness factor, simplifying assumptions would be needed, and the city and project stakeholders did not want to oversimplify or omit performance measures they felt to be critical in selecting an alternative for Cascade Avenue. The city used the project cost information in combination with the performance evaluation results and understanding of the project context to reach consensus with project stakeholders on a preferred alternative. 6.3.7 Selected Alternative The city and project stakeholders selected Alternative 2 as the preferred alternative. Alterna- tive 2 provides improved safety, reliability, access and QOS for transit riders, pedestrians and bicyclists. Within this alternative, the bicycle QOS is the least improved relative to transit riders and pedestriansâ anticipated experience. Within Alternative 2, bicyclists will need to share the transit lane with transit vehicles. This is an improvement over existing conditions because of the lower number of transit vehicles relative to automobiles and the width of the transit vehicle lane. The city felt most comfortable with the performance of Alternative 2. This is primarily because of the improvement in safety across modes and the preservation of reasonable mobility and reliability for motorists and transit vehicles. Cascade Avenue is a critical corridor for transit service within the city. There are limited parallel alternative routes for motorists to use in place of Cascade Avenue that are not through residential areas. For those reasons, it was of high importance to the city to maintain a reasonable degree of mobility and reliability for motorists and transit, while better serving other modes. The local business community that initiated the Cascade Avenue improvements preferred Alternative 3 and Alternative 2 as their secondary selection. Attributes from Alternative 3 that the city plans to integrate into Alternative 2 to address the business communityâs interests include adding landscaping along the sidewalks by using tree wells or other landscaping areas spaced at regular intervals. Attributes and characteristics to better serve bicyclists included elements such as bicycle corrals for easy parking in front of businesses, wayfinding signs for bicyclists, and signs and pavement markings to communicate to bicyclists and transit riders that bicyclists are permitted and encouraged to use the transit lane for travel. 6.4 Design Case Study C: High-Capacity Thoroughfare in Urbanizing Area This design alternatives case study is for creating a high-traffic capacity arterial roadway that also buffers adjacent users and land use from the traffic impact to the greatest extent possible. The original case study appears in Designing Walkable Urban Thoroughfares: A Context Sensitive Approach (ITE 2010a). Although the case study illustrates how a designer can evaluate design alternatives in a primarily qualitative manner, elements of quantitative analysis (e.g., employing more detailed quality, capacity and safety analysis procedures) also could be integrated into the design con- cept evaluation process. The context designations are the same as those used in Design Case Study A. Additional details about the guidance and support information used to develop the case study can be found in the original ITE document (ITE 2010a). 6.4.1 Design Objective Design a thoroughfare in a newly urbanized area that accommodates high levels of traffic and buffers adjacent land uses from traffic impacts.
250 Design Guide for Low-Speed Multimodal Roadways Stage 1: Review or develop an Area Transportation Plan. 6.4.2 Existing Street Characteristics (see Exhibits 6-13 and 6-14) Existing street is a five-lane undivided arterial street with the following characteristics: ⢠Functional classification: minor arterial; ⢠Right of way: 90 ft.; ⢠Four through-traffic lanes plus center turn lane, median; ⢠On-street parking: none; ⢠Existing ADT: 25,000â30,000 VPD; ⢠Projected ADT: 45,000 VPD; ⢠Speed limit: 40 mph; ⢠Percent heavy vehicles: 4â5 percent; ⢠Intersection spacing: 600â700 ft., with many driveways; ⢠Network pattern: suburban curvilinear; few alternative parallel routes; ⢠Center turn lane: TWLTL with turn bays at intersections; ⢠Transit: moderate-frequency regional and local routes; ⢠Bicycle facilities: designated bicycle route with 8-ft.-wide paved shoulders on both sides; ⢠Narrow attached sidewalks (5 ft.) on both sides; ⢠No landscaping within right-of-way; and ⢠Conventional street and safety lighting. Source: ITE (2010a) Exhibit 6-13. View of existing street. Source: ITE (2010a) Exhibit 6-14. Existing street cross section.
Case Studies: Designing for All Users 251 Stage 2: Understand community vision for context and thoroughfare. 6.4.3 Vision Area plans envision a mix of high-density housing, retail centers and low-intensity commer- cial uses fronting the street. Because the roadway accommodates high levels of through traffic, access control is desired. The roadway is currently a bicycle route with bicyclists using the paved shoulder, but bicycle lanes are desired to close gaps in the bicycle system. Adjacent properties provide off-street parking, but some fronting residential and commercial uses would benefit from on-street parking. The area will generate pedestrians who desire buffering from adjacent traffic. The area plan calls for a boulevard design including an alternative for a multiway boulevard with fronting access lanes to provide on-street parking and buffer proposed mixed use develop- ment with ground floor retail and housing above. Stage 3: Identify compatible thoroughfare types and context zones. ⢠Existing context zone: C-3; ⢠Future context zone: C-5; and ⢠Thoroughfare type: boulevard. Stage 4: Develop and test the initial thoroughfare design. 6.4.4 Desirable Design Elements Desirable design elements (prioritized by vision) are: ⢠Lower target speed (35 mph); ⢠Emphasis on vehicular capacity; ⢠Access management with landscaped median; ⢠Bicycle lanes; ⢠Streetside buffered from traffic; ⢠Street trees; ⢠Bus stops with shelters; ⢠Increased crossing opportunities at signalized intersections; ⢠Pockets of on-street parking adjacent to fronting commercial or mixed use development; and ⢠Multiway boulevard design adjacent to mixed use development. 6.4.5 Factors to Consider/Potential Trade-Offs Factors to consider/potential trade-offs include: ⢠Effective width for streetside buffer versus width requirements for elements in traveled way; ⢠Accommodation of wider than minimum sidewalks, particularly in commercial areas; ⢠Provision of on-street parking in select segments versus other design elements; ⢠Intersections spaced to optimize traffic flow versus need for increased crossing opportunities; ⢠Accommodation of large vehicles, particularly turning at intersections; ⢠Right-of-way requirements for implementing a multiway boulevard; and ⢠Efficient intersection operations with multiway boulevard. 6.4.6 Possible Alternative Solutions Possible alternative solutions (see Exhibit 6-15) are: ⢠Alternative 1: Emphasize streetside buffering and provision of bike lanes; provide minimal width median for access control and narrower travel lanes.
252 Design Guide for Low-Speed Multimodal Roadways ⢠Alternative 2: Implement multiway boulevard with local access streets that provide on-street parking and shared bicycle/vehicle environment. This allows a wider streetside area and removes bicycles from higher-speed roadway. This configuration requires 15 ft. of right-of- way acquisition on each side of roadway, or adjacent development dedicates streetside and on-street parking lane. ⢠Alternative 3: Emphasize landscaped median and bicycle lanes by narrowing streetside. Provides minimal sidewalk width and reduced buffer area. In all cases use grid network to divert some traffic from project thoroughfare. This may require operational or physical improvements to other streets. Traffic to be diverted will depend on travel patterns, context and design of other thoroughfares. Compare benefits of the three alternatives. Exhibit 6-16 demonstrates one way of showing such a comparison. 6.4.7 Selected Alternative Alternative 2 was selected as the solution. This alternative: ⢠Provides desirable design features, including the desire for a multiway boulevard; ⢠Is feasible to implement in newly urbanizing area with redevelopment opportunities; ⢠Requires either dedication or right-of-way acquisition, but could be implemented in phases; and ⢠Requires special design of intersections to maintain efficient operations. Stage 5: Develop a detailed thoroughfare design. Exhibits 6-17 through 6-19 show a schematic view of how the selected alternative might be designed. Source: ITE (2010a) Exhibit 6-15. Alternative street cross sections.
Case Studies: Designing for All Users 253 Source: ITE (2010a) Exhibit 6-16. Relative comparison of alternative trade-offs. Source: ITE (2010a) Exhibit 6-17. Schematic plan view of Alternative 2.
254 Design Guide for Low-Speed Multimodal Roadways 6.4.8 Solution Design Features Traveled Way: ⢠Target speed: 35 mph; ⢠Four, 11-ft. travel lanes in central roadway; ⢠Parallel, 18-ft.-wide local access lanes separated by 8-ft.-wide landscaped medians; ⢠Local access roads provide shared vehicle/bicycle lane and 9-ft. travel lane; and ⢠Left-turn lanes on central roadway at intersections. Streetside: ⢠12-ft. sidewalks; ⢠Pedestrian-scaled lighting; and ⢠Street trees in tree wells. Source: ITE (2010a) Exhibit 6-18. Alternative intersection design for Alternative 2. Source: ITE (2010a) Exhibit 6-19. Alternative intersection design for Alternative 2.
Case Studies: Designing for All Users 255 Intersections: ⢠Special design treatment required to accommodate multiple movements between central roadway and local access lanes; and ⢠Intersections widened to accommodate left-turn lane within the central roadway. Parallel Thoroughfares (as needed): ⢠Directional signing; ⢠Operational adjustments or improvements; and ⢠Physical improvements. 6.5 Design Case Study D: 27th Avenue The design alternatives case study for 27th Avenue is adapted from NCHRP Report 785: Performance-Based Analysis of Geometric Design of Highways and Streets (Ray et al. 2014). The purpose of this project is to design a new urban collector to provide additional connectivity in an industrial area and at the same time better balance modes using the roadway. This case study illustrates how the performance-based analysis suggested by NCHRP Report 785 can be incorporated into the design concept development process. It also demonstrates that evalu- ating and interpreting alternatives across multiple modes using a variety of performance measures can be a complicated exercise. For a more detailed version of this case study that includes the report authorâs notes, see NCHRP Report 785. This project example considers alternative alignments and cross sections for a new urban collector roadway, 27th Avenue, which is being designed to provide additional connectivity within and access to an industrial area. The overarching intended project outcome is to entice and encourage new employers to the newly zoned industrial area. The city, within which the industrial area is located, would like to increase its industrial employment base. The new urban collector would connect to the broader roadway network by way of existing US-33. The learning objectives for this project example are as follows: ⢠Illustrate how to consider the broader context before beginning the details of design; ⢠Demonstrate how the needs of different modes can be balanced; and ⢠Apply the performance-based analysis process within an EA. 6.5.1 Project Initiation Project Context The city is trying to increase the number of industrial employment opportunities to create a more well-rounded local economy. The city council approved expanding the industrial zone adjacent to the existing heart of the cityâs industrial land uses. To draw in larger industrial- type employers and supporting services, the city is going to construct some of the necessary street infrastructure to make the new area viable for employers. The area is bounded by a steep hillside to the west, the downtown core to the south, and existing industrial uses to the north and east. An existing highway, US-33, runs along the newly zoned areaâs northeasterly border. Exhibit 6-20 illustrates the location of the expanded industrial zone. Despite the proximity to rail, other industrial uses, and US-33 (a regional highway), there are some inhibitors for industrial employers. There is not sufficient connectivity within the newly zoned area to facilitate its use without heavy reliance on US-33. US-33 has relatively stringent access spacing standards, making it difficult to obtain access permits from the state DOT. Also, there are limited access points to the area and those that do exist are not consistently conducive
256 Design Guide for Low-Speed Multimodal Roadways to heavy-vehicle traffic. US-33 serves the existing industrial uses in the area while being a critical connection between the downtown and a regional park located to the north. As a result, US-33 is heavily traveled by recreational bicyclists traveling between downtown and the regional park. This high demand occurs despite the lack of bicycle lanes on US-33 and the variation in the paved shoulder width from 2 to 4 ft. along the corridor. 6.5.2 Intended Project Outcomes In this project example, the project purpose is to make improvements to the roadway network to encourage and entice employers to the existing industrial area. There are no direct geometric performance measures for evaluating how well a project alternative will encourage or entice employers to the industrial area. However, there are indirect geometric performance measures contributing to characteristics that would support encouraging employers within an industrial area (e.g., quality of service for large vehicles, access to regional highways or freeways). City planners would like to address some of the inhibitors for industrial employers, while also addressing some of the issues related to mixed bicycle and heavy-vehicle traffic on US-33 within an area that does not have sufficient space for both modes. The city has decided to focus their investment on improving connectivity within the newly zoned area. In doing so, it hopes Source: Ray et al. (2014) Exhibit 6-20. Existing conditions of new industrial area.
Case Studies: Designing for All Users 257 to address some of the deterrents for employers and explore ways to improve bicycle accom- modations from the downtown area to the regional park. The cityâs basic approach for achieving this goal is to plan, design, and construct a new urban collector, 27th Avenue, within the newly zoned industrial area. The city plans to seek federal funding for part of the 27th Avenue project. Enough work has been done to know the project does not qualify for a categorical exclusion, and so the city needs to perform an EA to determine if the project could result in significant environmental impacts. The project did not qualify for a categorical exclusion due to its proximity to the hillside (previously shown in Exhibit 6-20), which is a federally listed critical habitat. Considering the new 27th Avenue, the city will need to avoid, and demonstrate there is no, significant impact to the hillside from the 27th Avenue construction. If it is unable to demonstrate no significant impact, the city will need to produce an Environmental Impact Statement (EIS). The city would prefer to avoid significant environmental impact and, therefore, plans to adapt the 27th Avenue project design accordingly. With respect to funding, a LID has also been formed to generate funds for ongoing main- tenance and improvements within the newly zoned industrial area. The city will operate and maintain the roadway when it is constructed. The primary audience to be served by this project is heavy-vehicle operators who will need to be able to easily access and circulate within the industrial area. The city knows this is a critical factor industrial businesses consider in selecting their location. The secondary audience of users who also need to be considered in developing 27th Avenue are bicyclists and motorists traveling between the regional park and downtown districts. The other participating stakeholders are the business owners in the area participating in the LID that will help with funding 27th Avenue. From the cityâs perspective, the overarching intended outcome of the project is to entice industrial employers to the newly zoned industrial area. The city wishes to generate employment opportunities for a currently under-employed segment of the cityâs population. No clear direct performance measures connect design decisions to generation of additional industrial-based jobs within an area. Surrogate transportation performance categories and associated measures reflecting the type of roadway system industrial-based businesses value are identified as acces- sibility, quality of service, and safety. The performance measure to be used for access is the ease with which heavy vehicles will be able to navigate the industrial area and the quality of access to US-33 and the downtown. The performance measure selected to measure quality of service is MMLOS performance for bicyclists (to access the regional park) and transit riders (to serve employees accessing jobs within the industrial area). The expected frequency and severity of crashes will be used to measure safety. 6.5.3 Concept Development Geometric Influences The NCHRP Report 785 project team decided to focus the initial alternative development and analysis on two elements: (1) obtaining a finding of no significant environmental impact and (2) creating design attributes and parameters supporting the transportation performance measures previously identified. Roadway alignment is the primary factor influencing whether the 27th Avenue project can avoid a significant environmental impact. The critical habitat is part of the hillside and the base of the hillside along the western border of the newly zoned industrial area. Therefore, horizon- tal alignment of 27th Avenue is one area of focus and consideration with respect to geometric design decisions.
258 Design Guide for Low-Speed Multimodal Roadways In addition to the roadway alignment, the project team focused on defining a set of cross- section design parameters that can be used to develop 27th Avenue. The cross sections must balance some of the performance trade-offs between access for heavy vehicles, quality of service for bicyclists and transit riders, and safety across modes. The project team selected the following design parameters to explore because of their direct relationship to the previously mentioned performance measures: ⢠Intersection geometry as it relates to being able to accommodate large vehicles (e.g., radius of curb returns); ⢠Lane width; ⢠Bicycle facility presence and type (e.g., bicycle lanes); ⢠Ability to accommodate transit; and ⢠Sidewalk presence and width for pedestrians and transit riders. 6.5.4 Potential Solutions The project teamâs initial effort focused on defining the alignment for 27th Avenue. Three alignment options were developed and assessed based on their ability to avoid a significant envi- ronmental impact, provide access to US-33 and downtown, and facilitate circulation within the industrial-zoned area. In addition, the alignments ideally should not preclude reasonably sized parcels for large and smaller supporting employers. A brief description of each of the alignment options follows: ⢠Alignment 1 (US-33 and Interstate Access): Provides connection to US-33 and to I-7; divides the newly zoned area into four quadrants; ⢠Alignment 2 (Rail Yard and Port Access): Provides a direct connection to US-33, rail yard and port; divides the newly zoned area into two large parcels; and ⢠Alignment 3 (US-33, Interstate, and Downtown Access): Provides a connection to US-33, I-7, and three minor arterials in the northern downtown core; maintains the most contiguous amount of industrial land. Exhibit 6-21 illustrates the alignment options. Each of the alignment options can be paired with a set of design parameters helping to define the 27th Avenue cross section. The project team developed three sets of alternative design parameters considering the differ- ent road users to be served by 27th Avenue: ⢠Alternative 1 (Freight Oriented): A set of design parameters focused on characteristics facili- tating the movement of large vehicles; ⢠Alternative 2 (Freight with Bicycle Accommodations): A set of design parameters incorporating characteristics for large vehicles and bicyclists; and ⢠Alternative 3 (Complete Street): A set of design parameters considering characteristics of large vehicles, bicyclists, and transit riders. ⢠Resources used to develop solutions. The NCHRP Report 785 project team used A Policy on Geometric Design of Highways and Streets (AASHTO 2011a), the cityâs roadway design stan- dards, the stateâs highway design manual and the Urban Street Design Guide (NACTO 2013) as references and guidance documents to develop specific alternatives for evaluation. ⢠Solution development. In this project, the project team was challenged to consider a range of options for an alignment as well as cross-section characteristics to try to achieve the var- ied performance measures previously discussed. To keep the solution development within a reasonable scope of effort, the project team focused the alignment options on avoiding significant environmental impacts, providing access to the broader transportation network, and enabling onsite circulation. The options identified for the roadway cross-section design
Case Studies: Designing for All Users 259 parameters are focused on elements that provide sufficient space for heavy vehicles (as a form of accessibility), quality of service for bicyclists and transit riders, and safety. In developing the alignment options, some consideration also was given to how to augment the options to better serve (1) bicyclists currently using US-33 to access the regional park and (2) safety with respect to speed management. ⢠Alignment options for 27th Avenue. Alignment options for 27th Avenue were developed considering the connections to regional transportation facilities and the need to avoid a sig- nificant environmental impact. The potential connections to regional transportation facilities include the following: â US-33: A highway serving as a key transportation freight corridor reaching from coastal communities west of the industrial area to urban, suburban and rural mountain communi- ties east of the industrial area; â I-7: An Interstate freeway passing north-south through the state, connecting the majority of the major coastal cities and ports; â Rail yard: The rail yard is served by two major freight rail lines traversing east-west across the state, ultimately connecting to a major interstate rail hub; Source: Ray et al. (2014) Exhibit 6-21. Alignment options for 27th Avenue.
260 Design Guide for Low-Speed Multimodal Roadways â Port (river): Provides access to large merchant and freight-carrying ships with access to the ocean and, therefore, access to a wide range of global ports; and â Downtown: Connection to areas where employees will be traveling to and from their places of residence, and connection to existing transit service and bicycle boulevards. The NCHRP Report 785 project team explored different options and degrees of direct con- nections to these regional transportation facilities. There are advantages and disadvantages to directly connecting to any one of these regional facilities. The direct access can be attractive to industrial employers; however, depending on the existing operations of that facility, it may result in operational delays or limited capacities by adding industrial traffic directly to an already well-used facility. Directly connecting to the downtown also presents potential con- siderations with respect to cut-through traffic and the general advantages and disadvantages of expanding the downtown street grid. One key advantage the city wanted to capture in one of the options was the ability to pro- vide an alternate route and better quality route for bicyclists traveling to the regional park so bicyclists would not be forced to use US-33. ⢠Design parameters for 27th Avenue cross section. Design parameters for the 27th Avenue cross section were identified based on the road users that 27th Avenue is intended to serve. Any of the alternative cross sections can be paired with any one of the alignment options previously discussed. A common element between the cross sections is the consideration given to accommo- dating large vehicles needing to routinely access the industrial uses. As additional road user design elements were incorporated into the cross section, the project team tried to balance the ultimate roadway width with providing sufficient space for different road users. This was an ongoing trade-off in developing and evaluating the different cross sections. The city would like to keep the total cross-section width as narrow as possible while still meeting road usersâ needs. A narrower cross-section footprint will allow more space for the indus- trial uses and employers that the city would like to attract to the area. The clear trade-off in keeping the roadway cross-section footprint narrow is having less space to serve the large vehicles, bicyclists, and transit riders who are anticipated to use 27th Avenue. The city made one overarching design decision applied to each alternative cross section. The city decided 27th Avenue will be an undivided roadway facility; therefore, none of the alternatives could include a center median. The primary reason for this decision was to keep the roadway cross section open and free of physical obstacles, providing more space and options for drivers of heavy vehicles to navigate the industrial area. 6.5.5 Primary Alternatives for Evaluation Using the resources and considerations briefly described previously, the project team arrived at the alignment options shown in Exhibit 6-21 and the following alternative cross sections for evaluation: ⢠Alternative 1 (Freight Oriented): Two-lane roadway with 14-ft.-wide travel lanes and a 16-ft.- wide, two-way center left-turn lane (total three-lane cross section); the cross section includes curb-tight 5-ft.-wide sidewalks on both sides of the street (see Exhibit 6-22). ⢠Alternative 2 (Freight with Bicycle Accommodations): Two-lane roadway with 12-ft.-wide travel lanes and a 14-ft.-wide two-way center left-turn lane (total three-lane cross section); the cross section includes 6-ft.-wide bicycle lanes and curb-tight 5-ft.-wide sidewalks on both sides of the street (see Exhibit 6-23); and ⢠Alternative 3 (Complete Street): Two-lane roadway with 12-ft.-wide travel lanes and a 14-ft.-wide two-way center left-turn lane (total three-lane cross section); the cross section includes 5-ft.-wide bicycle lanes and 10-ft.-wide pedestrian space on both sides of the street (see Exhibit 6-24).
Case Studies: Designing for All Users 261 Source: Ray et al. (2014) Exhibit 6-22. Cross section of Alternative 1. Source: Ray et al. (2014) Exhibit 6-23. Cross section of Alternative 2. Source: Ray et al. (2014) Exhibit 6-24. Cross section of Alternative 3.
262 Design Guide for Low-Speed Multimodal Roadways The exhibits show there are a few common elements across the alternative cross sections: ⢠A two-way center turn lane to facilitate access to future industrial uses fronting 27th Avenue; ⢠Sidewalks to separate pedestrian activity and vehicle movement; and ⢠One through travel lane in each direction, which was deemed sufficient given that 27th Ave- nue will primarily facilitate internal circulation. 6.5.6 Evaluation and Selection The performance evaluation for the alternative alignment options was based on each align- mentâs ability to: ⢠Avoid significant environmental impacts; ⢠Facilitate circulation and connections to regional transportation facilities; ⢠Maintain contiguous parcels of land for industrial uses; and ⢠Create an improved alternative route to the regional park. The performance evaluation for the alternative cross sections focused on the following performance categories and associated measures: ⢠Safety, as defined by crash frequency, ⢠Accessibility, as defined by connectivity within the industrial area, connection to the regional park, connection to regional highways and ability to accommodate large vehicles; and ⢠QOS, as defined by accommodations for bicyclists and transit riders. The alignment options were evaluated qualitatively across the previously listed attributes. The project team used geographic information system (GIS) software, aerial imagery, initial surveys and preliminary engineering of the horizontal alignments to assess how each option performed relative to the attributes. The GIS mapping enabled the team to identify and deter- mine the locations of environmentally sensitive areas along and at the base of the hillside that needed to be avoided. The identification of sensitive areas considered the physical impact of the roadway and industrial development as well as where and how stormwater runoff from 27th Avenue and the newly zoned industrial area will be managed. The aerial imagery, initial survey of the industrial area and preliminary engineering of the horizontal alignments, paired with the GIS information, enabled the project team to complete informed assessments of the alignment options. Exhibit 6-25 summarizes the qualitative assessment results for the alignment options. Each alignment option was rated for the performance criteria using a scale of 0 to 3. A 0 indicates the option did not meet the criteria and a 3 indicates the option fulfills the criteria. Alignment Options Avoid Env. Significant Impact Connection to Regional Facilities Circulation within Area Contiguous Parcels of Land Improved Alternate Route to Regional Park Total Score 1: US-33 and I-7 Access 3 2 2 1 1 9 2: Rail Yard and Port Access 3 2 2 2 0 9 3: US-33, I-7 and Downtown Access 3 3 3 3 3 15 Source: Ray et al. (2014) Exhibit 6-25. Assessment of alignment options.
Case Studies: Designing for All Users 263 Alignment 3 scored the highest based on the criteria because this alignment: ⢠Avoids significant environmental impacts and establishes a western border for the newly zoned area. This means incoming industrial uses and employers will only be able to develop east of 27th Avenue. This guarantees no negative impacts to the hillside and will save inter- ested employers from having to evaluate and/or seek environmental clearance to move into the newly zoned area. ⢠Provides a connection to US-33 in two locations. This alignment also provides a direct con- nection to I-7 on- and off-ramps. Finally, it connects with three minor arterials in the northern downtown core. One arterial is an existing bicycle boulevard and one has an existing transit line. ⢠Provides circulation within the newly zoned area along the western and southern border. ⢠Maintains the largest amount of contiguous parcels of land, providing potential employers with flexibility in their site development. ⢠Provides a more direct connection and an alternate parallel route to US-33 for bicyclists to reach the regional park. Alignments 1 and 2 performed well for some of the evaluation criteria but were weakest in maintaining contiguous parcels of land for development and providing an alternate route to the regional park. For the alternative cross sections, the performance measures associated with the identified performance categories were estimated using the following resources: ⢠Safety. Chapter 12 of the AASHTO HSM (AASHTO 2010) was used to estimate the expected safety performance; ⢠Accessibility. Access was evaluated qualitatively based on the physical space allocated to heavy vehicles; access with respect to connectivity within the area and to regional transporta- tion facilities was captured in the assessment of the alignment options; ⢠QOS. The HCM 2010 MMLOS methodology (TRB 2010) was used to evaluate the quality of service (i.e., quality of the travel experience perceived by the road user) anticipated for bicyclists and transit riders. Exhibit 6-26 summarizes the evaluation results for each alternative. The qualitative scale used to evaluate access for heavy vehicles was a rating of poor, fair or good based on the degree to which the cross section is anticipated to accommodate heavy vehicles. As shown in Exhibit 6-26, each cross section is estimated to have the same number of crashes per year even though the alternatives involve differences in lane width, bicycle lane presence and width, and sidewalk width. The reason the expected crashes per year do not change across the alternatives is because the methodology in Chapter 12 of the HSM applicable to urban and suburban facilities is not able to quantify the safety effects of changes in lane width, presence or width of bicycle lanes, or the presence or width of sidewalks (AASHTO 2010). This is, in part, Alternave Cross Secons Safety (crashes/year) QOS Access for Heavy Vehicles Bicycle MMLOS Transit Riders MMLOS 1: Freight Oriented 2.3 E E Good 2: Freight with Bicycle 2.3 C C Fair 3: Complete Street 2.3 C B Fair Source: Ray et al. (2014) Exhibit 6-26. Evaluation of alternative cross sections.
264 Design Guide for Low-Speed Multimodal Roadways why the project team also evaluated the quality of service for bicyclists and transit riders using the HCM 2010 MMLOS methodology. That methodology is sensitive to the presence and width of bicycle lanes and sidewalks. Looking across the performance results of the alternative cross sections, Alternatives 2 and 3 seem to offer the more balanced options for multiple road users, whereas Alternative 1 clearly favors heavy-vehicle traffic. The project team developed cost estimates for each alignment option and alternative cross section to evaluate the financial feasibility of each combination for the 27th Avenue project. The cost estimates for the alignment took into consideration the length of the proposed alignment and the cost per linear foot of the alternative cross sections. The costs include considerations such as stormwater management, full-depth pavement given the anticipated high volume of heavy vehicles, signing, pavement markings, lighting and a contingency cost for unforeseen expenses or fluctuations in material costs. Exhibit 6-27 summarizes the cost estimates. The significant drivers of cost are the length of the alignment and width of the cross section. Alignment 3 is the longest alignment option; the cost estimates for the different cross sections for that option are greater than for alignments 1 and 2. Similarly, Alternative 3 is the widest cross sec- tion; therefore, across each of the alignment options, Alternative 3 has the highest associated cost. The project team did not estimate a benefit/cost ratio or calculate a cost-effectiveness factor for the different alignment options and alternative cross sections. To be able to calculate a ben- efit/cost ratio or cost-effectiveness factor, simplifying assumptions would be needed to convert the assessment of alignment options into monetary benefits. Additional assumptions would be needed to quantify the degree of access provided to heavy vehicles for each alternative. The proj- ect team determined such assumptions would be vulnerable to subjectivity and might convolute the assessments previously performed in the project. Therefore, the city used the cost estimates in combination with the performance evaluations to build internal consensus and solicit input from external stakeholders to work toward a selected alternative. 6.5.7 Selected Alternative The city and project stakeholders selected Alignment 3 paired with cross-section Alternative 2. Alignment 3 performed the best in the performance evaluation and especially well with respect to providing access to regional facilities and an alternate route for bicyclists to access the regional park. Alternative 2 was selected because it provided the most balanced means for serving heavy vehicles and bicyclists while managing cost and overall footprint of the roadway. Transit riders and pedestrians can also be served with Alternative 2 and, therefore, the city felt it was the most balanced overall solution. Alignment Opon Alternave Cross Secon Esmated Cost 1: US-33 and I-7 Access 1: Freight Oriented $1.1 million 2: Freight with Bicycle AccommodaÂons $1.3 million 3: Complete Street $1.5 million 2: Rail Yard and Port Access 1: Freight Oriented $700,000 2: Freight with Bicycle AccommodaÂons $850,000 3: Complete Street $1.0 million 3: US-33, I-7, and Downtown Access 1: Freight Oriented $1.3 million 2: Freight with Bicycle AccommodaÂons $1.4 million 3: Complete Street $1.6 million Source: Ray et al. (2014) Exhibit 6-27. Cost estimates for 27th Avenue.
