Transit Capacity and Quality of Service Manual, Third Edition (2013) / Chapter Skim
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1. User's Guide 2.
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From page 300... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 6.
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From page 301... ...
Transit Capacity and Quality of Service Manual, 3rd Edition LIST OF EXHIBITS Exhibit 6-1 Sources of Bus Delay Associated with Bus Stops .................................................... 6-3 Exhibit 6-2 Bus Acceleration Characteristics ...................................................................................
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Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-30 Median Busway Center Station Examples ............................................................ 6-33 Exhibit 6-31 Exclusive Bus Lane Examples ....................................................................................
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Transit Capacity and Quality of Service Manual, 3rd Edition Exhibit 6-66 Bus Stop Location Factor/!
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Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-92 Calculation Example: Traffic Blockage Factor fi by Stop ( veh/h)
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Factors that influence bus capacity also influence bus speeds and reliability-issues of interest to any size transit agency. See Chapter 3 for a discussion of these relationships.
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From page 306... ...
Transit Capacity and Quality of Service Manual, 3'd Edition • Section 9 provides a comprehensive example of the calculations involved in performing bus capacity and speed analyses. • Appendix A provides substitute exhibits in metric units for selected exhibits that use U.S.
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Delay affects bus speeds (a quality of service issue) and, ultimately, the cost to operate a bus route.
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Transit Capacity and Quality of Service Manual, 3'd Edition It can be seen from Exhibit 6-1 that dwell time and traffic signal delay are typically the largest contributors to the delay associated with serving a bus stop. However, over the course of a bus route with many stops, even relatively small delays can add up to significant time losses.
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A loading area is a curbside position where a single bus can load and unload passengers. Bus stops are formed from one or more loading areas.
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Transit Capacity and Quality of Service Manual, 3'd Edition passengers first spilled toward the front loading area and, later, toward the rear loading area, but would move into the optimal area when an opportunity presented itself (2)
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From page 311... ...
Dwell time can vary significantly from one bus to the next serving a stop. Section 5 provides estimates of the time required for loading wheelchairs and bicycles.
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Transit Capacity and Quality of Service Manual, 3'd Edition As can be seen from Exhibit 6-4, fare collection activities can sometimes more than double the minimum passenger service time. The placement of the fare collection device(s)
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From page 313... ...
Long traffic signal cycle lengths can promote bus bunching, particularly when headways are twice the traffic signal cycle length or less. Exhibit 6-5 On-Line and Off-Line Loading Areas Transit Capacity and Quality of Service Manual, 3rd Edition Bus operations are not the only consideration in setting traffic signal cycle lengths.
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From page 314... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Bus Facility Influences on Delay In addition to delays associated with individual stops, the roadway facility on which buses operate also contributes delays that affect bus speed, capacity, or both. The most important factors are: • Stop spacing-how often a bus must stop as it travels along a facility; • Exposure to general traffic-the less exclusive the facility, the more buses are exposed to delays caused by other traffic using the facility; • Facility design-in particular, the lack of ability for buses to move around each other or other traffic; and • Bus operations-the number of buses scheduled relative to capacity and how buses and routes are organized.
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From page 315... ...
Exhibit 6-7 Estimated Average Bus Speeds on GradeSeparated Busways (mi/h) Transit Capacity and Quality of Service Manual, 3rd Edition The ability to increase stop spacing depends in part on the quality of the pedestrian network in the area-can pedestrians safely and directly walk to the next-closest stop?
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Transit Capacity and Quality of Service Manual, 3'd Edition • Exclusive-Only other transit vehicles use the facility, but interactions with other vehicles occur where the facility is crossed by other roadways. Exclusive bus lanes are an example of this type of facility.
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Exhibit 6-9 On-Street Bus Stop Location Comparison Transit Capacity and Quality of Service Manual, 3rd Edition be considered. If traffic on the one-way street moves from left to right, for example, right-turning traffic volumes might suggest a far-side stop, while providing a convenient transfer to routes on the cross street might suggest a near-side stop.
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From page 318... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Special bus stops are sometimes located along freeway rights-of-way, usually at interchanges or on parallel frontage roads. These stops are used to reduce bus travel times by eliminating delays associated with exiting and reentering freeways.
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From page 319... ...
Exhibit 6-11 Bus Loading Areas, Stops, and Facilities Equation 6-1 Transit Capacity and Quality of Service Manual, 3rd Edition Bus Stopping Patterns How buses are organized when using a facility also affects speed and capacity. Platooning, where two or more buses travel the facility as a group, results in bus stops being used more efficiently.
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From page 320... ...
Transit Capacity and Quality of Service Manual, 3'd Edition The number of seconds in an hour available for bus movement is 3,600 sjh, multiplied by the percentage of the hour that buses can access the loading area-100% for stops away from traffic signals, or the gjC ratio for stops at traffic signals. The seconds that a design bus occupies the loading area consists of the following: • Average time spent serving passengers while the traffic signal is green (the average dwell time multiplied by the gjC ratio)
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From page 321... ...
Non-linear loading area designs are fully effective: doubling the number of loading areas doubles the stop's capacity. Exhibit 6-13 Loading Area Utilization Example Doubling the number of linear loading areas at a stop increases capacity by less than a factor of 2, due to bus blocking effects.
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Transit Capacity and Quality of Service Manual, 3'd Edition loading area 3, as bus #2 blocks access to loading area 1, leaving its potential capacity unavailable for the moment (Scenario 6)
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A managed lane is a lane that restricts usage to certain vehicle types-for example, buses and carpools or buses and toll-paying vehicles. Transit Capacity and Quality of Service Manual, 3rd Edition however, some of the traffic signal green time that would otherwise be available for bus movement into the bus stop is made unavailable, reducing the overall stop capacity.
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Transit Capacity and Quality of Service Manual, 3'd Edition Floor BRT Passenger Maximum Bus Type Length (ft) Level Features Doors Seats Standees a Small bus/minibus 18-30 High None 1 8-30 NA Standard bus 35 High None 2 35-40 NA 35 Low None 2 30-35 NA 40 High None 2 40-45 NA 40 Low None 2 37-43 30-34 40 Low Styling 2 39-47 32-46 40 Low Styling 3 33 49 Double-deck 40 Low None 2 79-89 10-15 Motor coach 45 High None 1 53-65 0 Articulated 60 High None 2-3 65 NA 60 Low None 2-3 61-64 53-57 60 Low None 3-4 43 57 60 Low Styling 2-3 58 NA 60 Low Styling 3-5 64 53 65 Low Styling 2-3 67 NA Purpose-built BRT 60 Low Yes 3/6c 37 67 60 Low Yes 4 27 90 Sources: TCRP Synthesis 75 (1)
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Exhibit 6-16 Planning-Level Bus Lane Service Volumes These service volumes may be used for planning purposes. More precise values for operations and design purposes should be computed from the capacity relationships and procedures presented later in the chapter.
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Transit Capacity and Quality of Service Manual, 3'd Edition values to design levels to reflect passenger flow variations within the 15-min peak period. Peak-hour factors are discussed in Section 5 of this chapter.
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Exhibit 6-19 Illustrative MixedTraffic Bus Capacities Transit Capacity and Quality of Service Manual, 3rd Edition Exhibit 6-18 indicates that as either right-turning volumes or pedestrian volumes conflicting with the right turns increase, the number of buses that can be reliably served in an hour by an urban street bus lane drops significantly. The combination of high right-turning volumes and high conflicting pedestrian volumes is especially detrimental to buses, as vehicles turning right from the bus lane must yield to pedestrians, and these vehicles in turn block those buses that not able to move into the adjacent lane.
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Transit Capacity and Quality of Service Manual, 3'd Edition 3. PREFERENTIAL TREATMENTS OVERVIEW This section presents information related to the implementation of bus preferential treatments.
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From page 329... ...
Bus preferential treatments defined. The net change in person delay is an important factor to consider before implementing transit priority measures.
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From page 330... ...
Transit Capacity and Quality of Service Manual, 3'd Edition BUSWAYS AND FREEWAY MANAGED LANES Facilities that provide segregated rights-of-way for buses offer a number of advantages that can improve service quality. Bus travel times, schedule adherence, and vehicle productivity are improved when buses are able to use higher-speed, uncongested facilities.
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Exhibit 6-20 At-Grade Busway Station Examples Bus tunnels. Exhibit 6-21 Bus Tunnel Examples Transit Capacity and Quality of Service Manual, 3rd Edition (a)
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Transit Capacity and Quality of Service Manual, 3'd Edition Impacts on Bus Operations Exhibit 6-22 presents typical impacts of preferential treatments on freeway bus operations. TravelTime Treatment Improvements Up to 10 percent; varies Busways depending on routing and other design details HOV lanes Up to 20 percent; varies on out of direction travel Freeway 3-15% of overall travel bus lanes time, up to 75% of delay Bus lane Up to 20%; up to 90% of bypasses ramp meter delay Person Delay Impacts Minimal to significant, depending on the project Significant, dependent on application Minimal to significant, highly dependent on the strategy and location Potentially significant Additional Considerations Applications include special detection technologies that distinguish buses from general traffic Travel time improvements are a function of the existing delay Potential disruptions to queue storage needs on ramps Sources: NCHRP Synthesis 185 (19)
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Exhibit 6-24 General Planning Guidelines for Busways and Freeway Managed Lanes When the term is used in the TCQSM, "managed lane" implies buses may always use the Jane and that other vehicle types may be allowed to use the lane. Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-24 presents planning guidelines for minimum bus or passenger volumes for busways and bus priority treatments associated with freeways .
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Transit Capacity and Quality of Service Manual, 3'd Edition Freeway Ramp Queue Bypasses Queue bypasses are a form of priority treatment that allows buses to avoid queues of vehicles (such as those that develop at freeway ramp meters) by providing a short managed lane that avoids the queue.
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From page 335... ...
Exhibit 6-27 Examples of Bus on Shoulder Operation (Minneapolis) Transit Capacity and Quality of Service Manual, 3rd Edition • Insufficient space or bus volumes exist to add a managed lane; • Four to six buses or more an hour use the freeway; • At least 10-ft (3-m)
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From page 336... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Intersection Type Delay Sources Signalized Insufficient traffic signal green time for bus approach Poor signal progression for buses All Inadequate vehicle detection at signals Queued vehicles on intersection approach On-street parking maneuvers Inadequate lane width Off-line bus stop reentry delay Right-turning traffic blocking access to stop Left-turning traffic blocking shared lane Bus lanes can be created by several means: • Redesignating an existing travel lane as a bus lane, • Narrowing existing lanes to provide an additional lane, • Widening the street to add a new lane, and • Restricting on-street parking (part-time or full-time) to provide a bus lane.
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From page 337... ...
Exhibit 6-30 Median Busway Center Station Examples Transit Capacity and Quality of Service Manual, 3rd Edition turns across the busway. Unsignalized minor intersections and local drive ways along the transitway are restricted to right-turn movements in and out.
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From page 338... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Exclusive Bus Lanes Exclusive bus lanes are developed along a roadway by widening or dedicating one or more existing general traffic or parking lanes for transit use. They can be peak period only, or all day.
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Exhibit 6-31 Exclusive Bus Lane Examples Exhibit 6-32 Contraflow Lane Examples Transit Capacity and Quality of Service Manual, 3rd Edition (a) Curbside bus lane with right-turn lane (Copenhagen)
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From page 340... ...
Transit Capacity and Quality of Service Manual, 3'd Edition travel are served alternately. Nevertheless, bi-directional lanes can provide a higher level of reliability compared to congested mixed-traffic operation over the same section.
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From page 341... ...
Transit Capacity and Quality of Service Manual, 3rd Edition transit lane, requiring buses not to use the lane when a train approaches. A demonstration project of an intermittent bus lane, using_ overhead signag~ and an inpavement lighting system, was conducted in Lisbon (25)
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From page 342... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Minimum One-Way Peak-Hour Volume Treatment Bus Passenger Related Land Use and Transportation Factors Bus streets or malls 80-100 3,200-4,000 Commercially oriented frontage. CBD curb bus lanes main street I 50-80 2 000-3 200 I commercially oriented frontage I I I Curb bus lanes, normal flow 30-40 1 200_1600 I At least 2 lanes available for other traffic in same ' ' direction.
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From page 343... ...
Exhibit 6-35 Degree of Bus Lane Impacts Exhibit 6-36 Observed Travel Time Savings with Urban Street Bus Lanes Transit Capacity and Quality of Service Manual, 3rd Edition Impacts of Median Busways and Exclusive Bus Lanes on Bus Operations The primary benefits of median busway and exclusive bus lane operations over mixed-traffic operations are (a) reduced conflict with general traffic, resulting in reduced transit travel time, and (b)
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From page 344... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-37 shows observed reliability improvements associated with urban street bus lanes. The improved reliability is measured by the percent change in the coefficient of variation of travel time (standard deviation divided by the mean)
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From page 345... ...
Exhibit 6-38 Types of Bus Signal Priority Systems Transit Capacity and Quality of Service Manual, 3rd Edition limited to date and require specialized equipment that is capable of optimizing signal timings in the field to respond to current traffic conditions and bus locations. Exhibit 6-38 summarizes common bus signal priority treatments.
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Transit Capacity and Quality of Service Manual, 3'd Edition RED TRUNCATION Bus approaches red signal J)
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Exhibit 6-41 Optical TSP System Example Transit Capacity and Quality of Service Manual, 3rd Edition TSP Technology Signal priority systems vary in complexity. Simple systems that rely on bus operator intervention reduce the amount of on-vehicle technology that is needed.
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From page 348... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Typical Conditions for Application There are a number of reasons to justify transit signal priority. However, signal priority should only be implemented at intersections whose traffic operations (including pedestrian and bicycle operations)
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From page 349... ...
Exhibit 6-42 Summary of TSP Benefits and Impacts Transit Capacity and Quality of Service Manual, 3rd Edition Reductions in bus travel time and travel time variability can result in operating and capital cost savings, when the total time saved from running time reductions and reduced schedule recovery requirements at the ends of routes equals or exceeds the route headway, as fewer buses can then serve the route at the same headway. Even when the time savings are not enough to save a bus immediately, TSP can postpone the day that an extra bus needs to be added to the route to maintain headways, by offsetting some of the increased running time resulting from increased traffic congestion (29)
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From page 350... ...
Transit Capacity and Quality of Service Manual, 3'd Edition SITE-SPECIFIC PRIORITY TREATMENTS Queue Jumps Overview A queue jump lane is a relatively short lane that is available for buses to bypass queues of general traffic at or prior to a signalized intersection, thus reducing delay to bus passengers. Example configurations include: • Buses enter a right- or left-turn lane (right-turn lanes being the most common)
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From page 351... ...
Exhibit 6-44 Example Queue Jump Applications with Bus Lanes Transit Capacity and Quality of Service Manual, 3rd Edition If TSP is provided, a separate, short signal phase is provided to allow the bus (and any turning vehicles in front of it) an early green indication to move into the through lane or bus loading area on the far side of the intersection, ahead of through traffic.
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From page 352... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Typical Conditions for Application Conditions that support the application of queue jump lanes include (14) : • Right-of-way availability; • Right-turn (or left-turn)
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From page 353... ...
Exhibit 6-45 Boarding Island Example Transit Capacity and Quality of Service Manual, 3rd Edition Before Traffic congestion in curb lane due to parking and turning maneuvers. ill ~ -- -- -- -- -- -- -After ill ~ - ~:::DL -~ II< Bus travels in faster lane, passengers load and unload at boarding island .
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From page 354... ...
Transit Capacity and Quality of Service Manual, 3'd Edition a stop flush with the regular curb line, as the area before or after the bus stop that would otherwise be used by buses to pull in or out of the stop can be used for additional parking. If bicycle lanes exist, they may need to be routed around the curb extension, creating potential pedestrian/bicycle or auto/bicycle conflicts.
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From page 355... ...
Transit Capacity and Quality of Service Manual, 3rd Edition • Near-side or mid-block stop location, • Support from local business or property owners for such treatments. Conditions that require special consideration include: • Two-lane streets (i.e., no passing opportunity)
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From page 356... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Treatment Advantages Exclusive Bus • Increases bus speed by reducing Lanes sources of delay Signal Priority • Improves reliability • Increases transit visibility • Reduces traffic signal delay • Improves reliability Disadvantages • Traffic/parking effects of eliminating an existing travel or parking lane must be carefully considered • Requires ongoing enforcement • Risks interrupting coordinated traffic signal operation • Risks lowering intersection LOS, if intersection is close to capacity • Requires interjurisdiction coordination • Cross-street buses may experience more delay than time saved by the favored routes Queue Bypass • Reduces delay from queues at ramp • Bus lane must be available and longer than the back Queue Jump Curb Extensions Boarding Islands meters or other locations of queue • Reduces delay from queues at signals • Right lane must be available and longer than the back of queue • Buses can leap-frog stopped traffic • Special transit signal required • Eliminates reentry delay • Riding comfort increased when buses don't pull in and out of stops • Increases on-street parking by eliminating need for taper associated with bus pullouts • More room for bus stop amenities • Reduces pedestrian crossing distance • Increases bus speed by allowing buses to use faster-moving left lane • Reduces green time available to other traffic • Bus drivers must be alert for the short period of priority green time • Requires at least two travel lanes in bus's direction of travel to avoid blocking traffic while passengers board and alight • Bicycle lanes require special consideration • Requires at least two travel lanes in bus's direction of travel and a significant speed difference between the two lanes • Uses more right-of-way than other measures • Pedestrian/ADA accessibility, comfort, and safety issues must be carefully considered Sources: City of Portland (27) and TCQSM, 1st Edition (34)
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From page 357... ...
Transit Capacity and Quality of Service Manual, 3rd Edition 4. OPERATIONAL TOOLS OVERVIEW The previous section focused on infrastructure treatments to improve bus speed and reliability.
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From page 358... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Bus stop relocation can also be a useful technique for reducing the impact of other vehicles on bus operations. For example, when a bus stop is located in an exclusive right-turn lane, queues of turning vehicles may inhibit bus access to the stop.
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From page 360... ...
Transit Capacity and Quality of Service Manual, 3'd Edition routes-for example, 10 TriMet routes plus routes operated by C-Tran were included in the "W" or "West" group illustrated in Exhibit 6-49. Each block face along the transit mall contained two bus stops, and each group stopped every other block, resulting in four groups in the skip-stop stopping pattern.
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From page 361... ...
Transit Capacity and Quality of Service Manual, 3rd Edition supervision; this can be difficult and is a rare practice in North America. More commonly, platoons can be developed by traffic signals, when several buses use the facility at the same time, much as platoons of vehicles form and move down the street together after having been stopped at a traffic signal.
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From page 362... ...
Transit Capacity and Quality of Service Manual, 3'd Edition (a) Left-turn exemption (Portland)
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From page 363... ...
Exhibit 6-51 Yield-to-Bus Law Notification Examples Exhibit 6-52 Bus Operations Tool Comparison Transit Capacity and Quality of Service Manual, 3rd Edition without yield-to-bus laws also use similar stickers appealing to motorist courtesy to let the bus back in. Oregon has developed a flashing electronic YIELD sign that has traffic control device status (i.e., motorists must obey it like they would a traffic signal or regulatory sign)
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From page 364... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 5. BUS CAPACITY METHODOLOGY INTRODUCTION This section presents a computational methodology for determining the bus and person capacity of loading areas, stops, and facilities .
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From page 365... ...
Transit Capacity and Quality of Service Manual, 3rd Edition STEP 1: DEFINE THE FACILITY As introduced earlier in the chapter (Exhibit 6-11, page 6-15) , bus capacity is calculated for three key locations: 1.
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From page 366... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Bus Stop Location Data • Position relative to the roadway. As was illustrated in Exhibit 6-5 (page 6-9)
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From page 367... ...
Exhibit 6-54 Bus Lane Types Transit Capacity and Quality of Service Manual, 3rd Edition Type 1 Type2 Type3 STEP 3: SET A DESIGN BUS STOP FAILURE RATE Buses have no use of adjacent lane • Channelized bus lanes (a, b) • Contraflow bus lanes (b, c)
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From page 368... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Consequently, bus capacity analysis incorporates the concept of a failure rate that sets how often a bus should arrive at a stop only to find all loading areas occupied. The selection of a design failure rate sets the bus stop's design capaciry-the number of buses that can be served in an hour at a desired level of operational reliability.
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From page 369... ...
Equation 6-2 Exhibit 6-55 Statistical Basis of Failure Rate Equation 6-3 Exhibit 6-56 Values of Z Associated with Given Failure Rates Transit Capacity and Quality of Service Manual, 3rd Edition The dwell time value t; corresponding to Z is incorporated in Equation 6-2: tam ti- td Z=-= -- s s where Z = standard normal variable corresponding to a desired failure rate, s = standard deviation of dwell times, tam = operating margin ( s ) , td = average dwell time ( s )
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From page 370... ...
Transit Capacity and Quality of Service Manual, 3'd Edition times would normally have to exceed 140 s (60-s average dwell time plus 80-s operating margin) before a queue would develop (assuming that bus arrivals at the stop are spread out over the hour, rather than scheduled to occur at the same times)
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From page 371... ...
Archived A VL data can be a valuable source of dwell time, but may require cleaning before use in a capacity analysis. See Appendix C for details.
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From page 372... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Available Door Channels 2 3 4 6 Percent Passengers Through the Busiest Door Channel Boarding Alighting 60% 75% 45% 45% 35% 35% 25% 25% Source: Derived from Exhibit 4-3 in TCQSM, 2nd Edition (5)
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From page 373... ...
Waiting area LOS is defined in Chapter 10. Analyst judgment should be used to develop boarding lost times for bus stops with 2, 4, or 5 loading areas.
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From page 374... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Impacts of Infrequent Events on Dwell Time Impact of Wheelchair Movements on Dwell Time New transit buses in the United States are equipped with wheelchair lifts or ramps. When a lift is in use, the door is blocked from use by other passengers.
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From page 375... ...
Loading area capacity is the number of buses per hour that can use a single loading area at a bus stop at the design failure rate. Equation 6-6 Clearance time calculation.
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From page 376... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Various studies have examined clearance time, with values ranging from 9 to 20 s (39)
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Equation 6-7 Equation 6-8 Exhibit 6-59 Average Bus Reentry Delay (Stops Not Near Traffic Signals) with: where d re,l = Cre = Ma = v = Cch = CJ = e = 3,600 = Transit Capacity and Quality of Service Manual, 3rd Edition ( 3,600)
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From page 378... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Queue Service Delay The time 9s required to service a queue of vehicles that has been stopped for a red light at a traffic signal is ( 40) : with: where 9s = Q, = Sf= QT 9s= -- -- -- (stf3 ,600)
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From page 379... ...
Exhibit 6-61 Illustrative Queue Service Delays (s) (100-s Cycle Length)
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From page 380... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Reentry Delay for Far-Side Stops At far-side stops, buses can depart at any time traffic in the adjacent lane permits. Reentry delay is the average of queue service delay and gap-in-traffic delay, weighted by the proportion of time each condition occurs: dqs (C- dq5 )
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From page 381... ...
Exhibit 6-62 Illustrative Reentry Delay by Case Transit Capacity and Quality of Service Manual, 3rd Edition 50
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From page 382... ...
Transit Capacity and Quality of Service Manual, 3'd Edition will be inaccessible at a given point in time. The concept of effective loading areas is used to describe this effect, where the second linear loading area provides less capacity than the first, the third adds even less, and so on.
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From page 383... ...
Turning movements at intersections with bus stops reduce bus stop capacity. Exhibit 6-64 Examples of Auto Turning Conflicts with Buses Exhibit 6-65 Right-Turn Vehicle Capacities err for Planning Applications (veh/h)
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From page 384... ...
Transit Capacity and Quality of Service Manual, 3'd Edition The curb lane capacity cc~, in vehicles per hour, is the average of the through and right-turn capacities, weighted by their respective volumes. The effects of traffic blockage reduce bus capacity in proportion to the following adjustment factor fib (21)
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From page 385... ...
Transit Capacity and Quality of Service Manual, 3rd Edition capacity of other bus facilities before or after the non-stop section (e.g., downtown streets in Ottawa) , or the capacity of the bus terminal(s)
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From page 386... ...
Transit Capacity and Quality of Service Manual, 3'd Edition mix of service types (e.g., local and limited stop) uses the facility, the critical stop will be the bus stop used by all service types that has the lowest capacity.
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From page 387... ...
Exhibit 6-67 Typical Values of Adjustment Factor fk for Availability of Adjacent Lanes Exhibit 6-68 Values of Adjustment Factor fk for Type 2 Bus Lanes with Alternate Two-Block Skip-Stops When a mix of stopping patterns is used, stops other than the critical stop may have capacity problems. Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-6 7 gives representative values of the adjustment factor fi for various lane types, bus arrival types, and bus stopping patterns.
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From page 388... ...
Transit Capacity and Quality of Service Manual, 3'd Edition The capacities determined in Steps 5-7 are hourly capacities that assume that bus arrivals are spread out over the course of the hour. If bus arrivals are more concentrated during a particular portion of the hour (e.g., peaking over a 15- or 30-min period)
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From page 389... ...
PHF values range from 0.25 (all passenger demand occurs during a single 15-min period in an hour) to 1.00 (demand is constant throughout the hour)
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From page 390... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 6. BUS SPEED METHODOLOGY This section presents a computational methodology for estimating bus speeds on all types of bus facilities except freeway managed lanes.
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From page 391... ...
Use a 25% failure rate when estimating a section's maximum capacity. The HCM's urban street transit speed estimation method can be substituted for Step 4 when intersection-level traffic volume and signal timing data are available.
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From page 392... ...
Transit Capacity and Quality of Service Manual, 3'd Edition The acceleration and deceleration time per stop is the time spent slowing from the facility's running speed to a stop and accelerating back to running speed. where CtVrun tacc = -- a CtVrun tdec = -- dtacc = acceleration time (slstop )
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From page 393... ...
Equation 6-32 Equation 6-33 The average dwell time used here is the average of all stops along the section, rather than the average critical stop dwell time used for capacity analysis. Exhibit 6-70 Illustrative Unimpeded Running Time Rates (min/mi)
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From page 394... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Average Sto12s 12er mile Dwell Time (s) 0.5 1 1.5 2 2.5 0 1.38 1.56 1.75 1.93 2.11 15 1.56 1.88 2.22 2.56 2.90 30 1.75 2.13 2.60 3.06 3.53 45 1.93 2.38 2.97 3.56 4.15 60 2.11 2.63 3.35 4.06 4.78 Source: Calculated.
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From page 395... ...
Equation 6-34 Equation 6-35 Transit Capacity and Quality of Service Manual, 3rd Edition Step 4c: Calculate the Base Bus Running Time Rate The base bus running time tr (in minutes per mile or kilometer) is the sum of the unimpeded running time tu and the additional running time losses t1: tr = tu + tl STEP 5: ADJUST FOR SKIP-STOP OPERATION Skip-stop operation spreads buses out among a series of bus stops, allowing for an increase in speeds.
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From page 396... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Exhibit 6-7 4 illustrates values of the stop-pattern adjustment factor for a two-block stop pattern, for a range of bus lane and adjacent lane volume-to-capacity ratios. As bus volumes, adjacent lane volumes, or both increase, the stop-pattern adjustment factor value decreases, indicating a lower potential for bus speed improvements as a result of the skip-stop pattern.
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From page 397... ...
Exhibit 6-75 Bus-Bus Interference Factor ! bb Values Equation 6-36 Equation 6-37 Transit Capacity and Quality of Service Manual, 3'd Edition simulation of Type 1 and Type 2 exclusive bus lanes, using an 80-s traffic signal cycle length, agjC ratio of 0.5, 400-ft (125-m)
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From page 398... ...
Transit Capacity and Quality of Service Manual, 3'd Edition STEP 8: DETERMINE AVERAGE FACILITY SPEED The travel time rates for each section are multiplied by the respective section lengths and then summed to produce a total travel time for the facility: where tfac = facility travel time (min) , Nsec tfac = L ts,iLi i=l Nsec = number of sections forming the facility, tsJ = section running time rate for section i (minjmi or minjkm)
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From page 399... ...
Transit Capacity and Quality of Service Manual, 3rd Edition 7. BUS RELIABILITY This section presents the state of knowledge about factors that influence bus reliability.
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From page 400... ...
Transit Capacity and Quality of Service Manual, 3'd Edition SCHEDULING AND HOLDING STRATEGIES A Dutch study (50) investigated schedule- and headway-based holding strategies for short headway transit services.
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From page 401... ...
Transit Capacity and Quality of Service Manual, 3rd Edition APPLICATIONS OF AVL DATA TCRP Report 113 (38) provides information on designing a system to archive AVL data and to apply the collected data to various types of analyses that support a transit agency's operations, scheduling, and management functions.
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From page 402... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 8. APPLICATIONS This section presents examples of the types of real-world situations that this chapter's methods can be applied to.
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From page 403... ...
Transit Capacity and Quality of Service Manual, 3rd Edition flash passes) , the additional step of recording number of fares paid by media type will be required.
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From page 404... ...
Transit Capacity and Quality of Service Manual, 3'd Edition representative delay reduction value. This value should then be reduced to reflect the percentage of bus stops at traffic signals where queue jumps would be installed.
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From page 405... ...
Transit Capacity and Quality of Service Manual, 3rd Edition 6. Apply the TCQSM to determine (a)
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From page 406... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 9. CALCULATION EXAMPLE THE SITUATION Carroll City, the central city in a region of 750,000 people, is examining opportunities to improve transit service through its downtown core as part of a Downtown Circulation Plan.
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From page 407... ...
Transit Capacity and Quality of Service Manual, 3rd Edition BUS CAPACITY Step 1. Define the Facility Under both existing conditions and Design Options 1 and 2, the facility consists of the one-way couplet of Carroll Street and George Street through the downtown core.
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From page 408... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Carroll Street Bus Sto12s 1 2 3 4 5 6 7 8 Number of loading areas 1 1 2 2 2 2 1 1 Curb-lane volume (veh/h) 450 500 500 550 600 650 600 600 Right-turn volume (veh/h)
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From page 409... ...
Exhibit 6-78 Calculation Example: Average Boardings and Alightings by Door ChannelExisting Conditions Transit Capacity and Quality of Service Manual, 3rd Edition channel 2 (default value) , with the remaining 75% of passengers using the rear door (channel 3)
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From page 410... ...
Transit Capacity and Quality of Service Manual, 3'd Edition tpf,i = Pa,ita,i + Pb,itb,i tpf,l = 0 + (1.4)
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From page 411... ...
Transit Capacity and Quality of Service Manual, 3rd Edition bus to pull in) plus reentry delay.
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From page 412... ...
Transit Capacity and Quality of Service Manual, 3'd Edition weighted by the proportion of time a platoon of vehicles is and is not present, respectively. For Stop #1 on Carroll Street, the calculations are as follows : dqs (C- dqs)
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From page 413... ...
Exhibit 6-83 Calculation Example: Bus Stop CapacityExisting Conditions Transit Capacity and Quality of Service Manual, 3rd Edition Adjust Capacity for Traffic Blockage Use Equation 6-17 to calculate the traffic blockage adjustment factor /th· The bus stop location factor fi is 0.5 because stops are located far side and buses are able to move into the adjacent travel lane as needed. The capacity of the curb lane through movement Cth is estimated as 1,625 x (gjC)
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From page 414... ...
Transit Capacity and Quality of Service Manual, 3'd Edition direction, the result of 25 buses per hour for the design capacity on Carroll Street indicates that the desired 15% failure rate cannot be achieved and that buses will experience less reliable operations than planned. BUS SPEED Step 1: Define the Facility Under the existing conditions and Design Options 1 and 2, the facility consists of the one-way couplet of Carroll Street and George Street through the downtown core.
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From page 415... ...
Transit Capacity and Quality of Service Manual, 3rd Edition Similarly, the time spent accelerating back to running speed from a stop, assuming an average standard bus acceleration rate of 3.4 ftjs 2 to 25 mijh, is calculated from Equation 6-27: CtVrun (1.47)
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From page 416... ...
Transit Capacity and Quality of Service Manual, 3'd Edition base bus running time is 9.18 min/mi for Carroll Street and 9.06 min/mi for George Street. Step 5: Adjust for Skip-Stop Operations As skip-stop operations are not being used under existing conditions, no adjustment needs to be made (i.e .,fsp = 1)
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From page 418... ...
Transit Capacity and Quality of Service Manual, 3'd Edition As before, passenger service times are increased by 20% for door channels where the minor flow is more than 25% of the total passenger flow through the door. Determine Average Passenger Flow Time for Each Bus Door Channel Equation 6-4 is used to calculate the passenger flow time for each door channel.
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From page 419... ...
Exhibit 6-86 Calculation Example: Average Dwell Time by Stop (s) -Pay-onExit Exhibit 6-87 Calculation Example: Summary of Impacts-Pay-on-Exit Transit Capacity and Quality of Service Manual, 3rd Edition Bus Stop 1 2 3 4 5 6 7 8 Carroll Street 10 10 23 21 24 15 6 9 George Street 9 13 21 18 26 17 9 7 Assessment of Capacity and Speed Impacts Exhibit 6-87 shows the bus capacity and speed impacts results associated with Operations Option 1.
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From page 420... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Bus Stop 1/2 3/4 5/6 7/8 Carroll Street 81 35 28 22 29 82 26 40 26 21 George Street 81 22 28 29 27 20 25 24 30 Use Equation 6-19 to calculate design bus facility capacity: Carroll Street: B = fk(B1 + B2 )
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From page 421... ...
Exhibit 6-89 Calculation Example: Summary of Impacts-Skip Stops Transit Capacity and Quality of Service Manual, 3rd Edition George Street, the bus volume-to-capacity ratio is 0. 7 4 and the corresponding bus-bus interference factor is 0.86.
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From page 422... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Bus Sto12 1 2 3 4 5 6 7 8 Carroll Street 78 65 43 62 38 48 78 60 George Street 87 71 48 43 52 38 71 78 The remainder of the bus capacity and speed procedures are performed as shown previously for existing conditions, with the exception that the number of effective loading areas should be recalculated using Exhibit 6-63 using the "on-line, random arrivals" column, resulting in the stops with two physical loading areas providing 1.75 effective loading areas. Assessment of Capacity and Speed Impacts Exhibit 6-91 shows the bus capacity and speed impacts results associated with Design Option 1, taking the average of the two bus groups for Carroll Street and George Street.
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From page 423... ...
Exhibit 6-92 Calculation Example: Traffic Blockage Factor f, by Stop (veh/h) Exhibit 6-93 Calculation Example: Summary of Design Option 2 Impacts, No Skip-Stop Operation Transit Capacity and Quality of Service Manual, 3rd Edition the through volume reflecting the scheduled number of buses and the right-turn volume reflecting the values given in Exhibit 6-76.
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From page 424... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 10.
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From page 425... ...
Transit Capacity and Quality of Service Manual, 3rd Edition 13. Transportation Research Circular 212: Interim Materials in Highway Capacity.
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From page 426... ...
Transit Capacity and Quality of Service Manual, 3'd Edition Transportation Research Board, Washington, D.C., Jan.
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From page 427... ...
Transit Capacity and Quality of Service Manual, 3rd Edition 38. Furth, P.G., B
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From page 428... ...
Transit Capacity and Quality of Service Manual, 3'd Edition 52. Altun, S.Z.
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From page 429... ...
Exhibit 6-7m Estimated Average Bus Speeds on GradeSeparated Busways (km/h) Exhibit 6-73m Estimated Base Bus Running Time Losses, t1 (min/km)
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From page 430... ...
Transit Capacity and Quality of Service Manual, 3'd Edition APPENDIX B: DWELL TIME DATA COLLECTION INTRODUCTION As discussed in Section 2, passenger service times (and dwell times) can vary greatly depending on many factors .
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From page 431... ...
Exhibit 6-81 Sample Passenger Service Time Data Collection Sheet Transit Capacity and Quality of Service Manual, 3rd Edition number of passengers on board may be estimated by counting the number of vacant seats or the number of standees)
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From page 432... ...
Transit Capacity and Quality of Service Manual, 3'd Edition open, end of passenger flow, doors close columns can be omitted. The following are steps that may be used to collect field data for estimating dwell times: 1.
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From page 433... ...
Predictable surges in demand may be accommodated by adjusting headways or adding an extra bus. Tweaking the schedule is less effective for handling random surges.
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From page 434... ...
Transit Capacity and Quality of Service Manual, 3'd Edition where f fetf = 1 + c vh fetJ = effective frequency (bus/h) , f = scheduled frequency (bus/h)
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Key Terms
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