The National Academies Press

Currently Skimming:

Pages 36-67

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 36... ... 36 C H A P T E R 4 This chapter contains five case examples of North American transit agencies that responded to the survey and have relatively robust and well-established bus TSP systems and practices. The synthesis team contacted selected case example agencies and arranged a web conference with transit agency staff. Read the entire page →
From page 37... ... Case Examples 37 Table 20. Case example agency key operational statistics. Read the entire page →
From page 38... ... 38 Transit Signal Priority: Current State of the Practice Both MTS and SANDAG played a constructor and designer role during TSP deployment. TSP deployments have been funded locally, primarily with funds from TransNet, a one-half-cent sales tax in San Diego County for transportation, first approved in 1987 and extended in 2004. Read the entire page →
From page 39... ... Case Examples 39 Granting Priority MTS aims to provide as much priority to the buses as possible, but there is some variation between intersections. The starting point for a green extension or early green duration parameter is 20 seconds, or 10 seconds for left turns. Read the entire page →
From page 40... ... 40 Transit Signal Priority: Current State of the Practice priority requests when they enter the detection range of a signal. Detection is done through infrared emitters in some locations and in-pavement loop detectors in other locations where there are dedicated bus lanes. Read the entire page →
From page 41... ... Case Examples 41 divisions relevant to this case example are Sustainable Streets, responsible for streets, parking, and traffic signals, and Transit, the transit agency, also referred to as the San Francisco Municipal Railway (Muni) Read the entire page →
From page 42... ... 42 Transit Signal Priority: Current State of the Practice is responsible for the hardware attached to the signal controller that receives and processes TSP requests. The transit agency owns and maintains the bus fleet and is responsible for the GPS receivers on the buses. Read the entire page →
From page 43... ... Case Examples 43 Bus TSP Business Rules and Parameters SFMTA's current TSP system uses a similar set of business rules and parameters at all intersections, giving SFMTA one deployment group. Establishing Business Rules and Parameters The current business rules and parameters were based on intuition and SFMTA's experience operating traffic signals and buses. Read the entire page →
From page 44... ... 44 Transit Signal Priority: Current State of the Practice to onboard equipment. Issues with the traffic signal equipment are flagged and investigated by SFMTA. Read the entire page →
From page 45... ... Case Examples 45 Notable Practices SFMTA's use of service differentiation and experience with transportation policy is notable, and different from many other agencies that participated in the survey. • Service differentiation. Read the entire page →
From page 46... ... 46 Transit Signal Priority: Current State of the Practice TTC was selected as a case example to represent large bus operators and the Canadian experience with TSP. It was the earliest adopter of TSP in the survey (first deployment in 1991) Read the entire page →
From page 47... ... Case Examples 47 on the route (more intersections provide more opportunities for time savings) Read the entire page →
From page 48... ... 48 Transit Signal Priority: Current State of the Practice the detection zone. (For detection zones with bus stops, expected dwell time is considered in the timing of the priority request.) Read the entire page →
From page 49... ... Case Examples 49 schedule based, and all transit vehicles will be provided with a TSP feature if they are in the detection zone at the decision point associated with that specific feature. A request for a green extension is granted only if there is a high probability that the transit vehicle making the request will clear the intersection within the design extension, which is typically 14 or 20 seconds depending on the intersection, and if the transit vehicle is still in the detection zone at the "normal" end of the green phase (or the "normal" end of the walk phase, depending on the green extension algorithm used) Read the entire page →
From page 50... ... 50 Transit Signal Priority: Current State of the Practice Operations, Monitoring, and Maintenance TTC has a Can$1,000 annual budget per TSP-equipped intersection for TSP operations and maintenance, and it reports that long-term TSP operation and equipment maintenance has not been a problem. Because the hardware was originally developed from streetcar track technology, it has been extremely robust: check-in and check-out locations are accurate to within 1 m and are very reliable, except where in-ground loop antennas or detector lead-in cables have been damaged by construction. Read the entire page →
From page 51... ... Case Examples 51 TTC has noticed that some semi-actuated signals function like fixed-time signals during peak periods, because the "maximum" side street is always required because of high pedestrian volumes. In addition, at most semi-actuated signals in Toronto, the side street is programmed to be at or near the pedestrian minimum timings. Read the entire page →
From page 52... ... 52 Transit Signal Priority: Current State of the Practice Lessons Learned TTC has significant experience developing TSP algorithms and operating TSP, and has identified several factors that have played a key role in its system. • Key parameters. Read the entire page →
From page 53... ... Case Examples 53 serves 30 stops. Currently, the R-Line is the sole route on which TSP has been deployed; however, RIPTA is currently engaged in a regional transit master planning effort in which several corridors have been identified for future TSP implementation. Read the entire page →
From page 54... ... 54 Transit Signal Priority: Current State of the Practice Requesting Priority The R-Line TSP deployment allows buses to unconditionally request an early green (3 to 5 seconds) and green extensions (4 to 5 seconds) Read the entire page →
From page 55... ... Case Examples 55 Notable Practices Unconditional Basis. RIPTA's TSP deployment is unconditional -- not based on schedule or headway adherence rules. Read the entire page →
From page 56... ... 56 Transit Signal Priority: Current State of the Practice systems were available, giving it extensive experience with different technologies, business rules, and strategies for deploying TSP. Bus TSP Program Overview King County Metro deploys TSP at 200 intersections, focusing TSP efforts on its six RapidRide routes. Read the entire page →
From page 57... ... Case Examples 57 In 2010, King County Metro began deploying its RapidRide service model and reconfigured the existing TSP system architecture to use a more reliable vehicle-to-infrastructure communications technology, using a corridor-based roadside wireless network. (More details about this system architecture are provided in later sections of this case example.) Read the entire page →
From page 58... ... 58 Transit Signal Priority: Current State of the Practice the SCATS adaptive signaling system. SCATS does not include support for TSP as an out-ofthe-box feature. Read the entire page →
From page 59... ... Case Examples 59 To deploy and optimize TSP for portions of the RapidRide B Line in the City of Bellevue, King County Metro and the City of Bellevue partnered to support consultant expenses associated with programming the city's SCATS system. However, there is not an ongoing formalized exchange of resources. Read the entire page →
From page 60... ... 60 Transit Signal Priority: Current State of the Practice intersections only. All intersections have a 120- to 180-second lockout rule. Read the entire page →
From page 61... ... Case Examples 61 Special Rules and Exceptions. In the RapidRide C–D Optimization group, there are several special rules and exceptions -- some of which are applied to all intersections and others to specific intersections only. Read the entire page →
From page 62... ... 62 Transit Signal Priority: Current State of the Practice firmware upgrades, stakeholders upgrade or completely change their signaling systems, or local stakeholders sometimes change signal timing to deal with acute challenges and may not communicate these changes to King County Metro. In some cases, these changes may eliminate established TSP strategies or may conflict with established TSP business rules and parameters. Read the entire page →
From page 63... ... Case Examples 63 off with a period when TSP was turned on. King County Metro found corridor travel time savings of between 1% and 6% and found that most intersections experienced reductions in approach delay. Read the entire page →
From page 64... ... 64 Transit Signal Priority: Current State of the Practice to 17.8% (a 30% reduction) Read the entire page →
From page 65... ... Case Examples 65 Challenges King County Metro has overcome many challenges during its implementation and ongoing optimization of its TSP system; however, a few challenges are highlighted as follows. • Limitations of signaling systems. Read the entire page →
From page 66... ... 66 Transit Signal Priority: Current State of the Practice Metro and local stakeholders can see improvements in transit service while maintaining intersection capacity for other road users. • Evidence-based TSP evaluation. Read the entire page →
From page 67... ... Case Examples 67 Table 28. Summary of case examples: Challenges, notable practices, and lessons learned. Read the entire page →

From page 36...

... 36 C H A P T E R 4 This chapter contains five case examples of North American transit agencies that responded to the survey and have relatively robust and well-established bus TSP systems and practices. The synthesis team contacted selected case example agencies and arranged a web conference with transit agency staff.