National Academies Press: OpenBook

Multimodal Level of Service Analysis for Urban Streets (2008)

Chapter: Chapter 9 - Integrated Multimodal LOS Model Framework

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Page 92
Suggested Citation:"Chapter 9 - Integrated Multimodal LOS Model Framework." National Academies of Sciences, Engineering, and Medicine. 2008. Multimodal Level of Service Analysis for Urban Streets. Washington, DC: The National Academies Press. doi: 10.17226/14175.
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Suggested Citation:"Chapter 9 - Integrated Multimodal LOS Model Framework." National Academies of Sciences, Engineering, and Medicine. 2008. Multimodal Level of Service Analysis for Urban Streets. Washington, DC: The National Academies Press. doi: 10.17226/14175.
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Page 94
Suggested Citation:"Chapter 9 - Integrated Multimodal LOS Model Framework." National Academies of Sciences, Engineering, and Medicine. 2008. Multimodal Level of Service Analysis for Urban Streets. Washington, DC: The National Academies Press. doi: 10.17226/14175.
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Page 95
Suggested Citation:"Chapter 9 - Integrated Multimodal LOS Model Framework." National Academies of Sciences, Engineering, and Medicine. 2008. Multimodal Level of Service Analysis for Urban Streets. Washington, DC: The National Academies Press. doi: 10.17226/14175.
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Page 95

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92 This section provides an overview of the proposed urban street LOS framework and the proposed LOS modeling system. 9.1 The Framework The proposed multimodal LOS framework for urban streets reports a single average level of service for each of four modal users of the urban street: 1. Auto drivers, 2. Bus passengers, 3. Bicycle riders, and 4. Pedestrians. The individual modal levels of service are NOT combined into a single comprehensive level of service for the facility be- cause this would disguise the disparities in the perceptions of quality of service for the four modes. The urban street LOS for a given mode is defined as the average degree of satisfaction with the urban street that would be reported by a large group of travelers using that mode of travel if they had traveled the full length of the study section of the street. The video lab research showed that the degree of satisfaction experienced by an individual traveler for a given situation varies widely across individuals. Consequently, this framework focuses on predicting the average degree of satis- faction of a large group of people exposed to the same urban street experience. Due to fatigue effects, travelers actually traveling the full length of the facility would forget key aspects of their experience and report a different level of service than would several travelers traveling short lengths of the facility. This framework takes the LOS perceptions of travelers on short sections of urban street and compiles them into an es- timate of LOS for the full length of the street. The six-letter grade A-F LOS structure of the HCM has been preserved. Many of the statistical results suggest that people can actually distinguish only two to three levels of service. However, public agency planners and engineers need to be able to predict how close a facility is to an unacceptable level of service. So the six levels have been retained for agency planning purposes, rather than because people actually can distinguish among them. Level of service is defined for each mode as shown in Exhibit 98. 9.2 The Integrated LOS Modeling System The proposed LOS modeling system relies on 37 variables to predict the perceived degree of satisfaction experienced by travelers on the urban street. These variables consist of four basic types: facility design, facility control, transit ser- vice characteristics, and the volume of vehicle traffic on the facility. Input Variable Interactions Among Modes Exhibit 99 lists the input variables and their major interac- tions. Minor interactions are not shown in this exhibit, but are discussed below. The Auto LOS Model 1 uses two variables: Auto Stops Per Mile, and Presence of Left-Turn Lanes. • The presence of a left-turn lane is a facility design feature. • The stops per mile are directly influenced by the intersec- tion control type and the settings of the traffic signal. High auto and transit volumes can increase the probability of stopping. Pedestrian and bicycle volumes at intersections reduce the saturation flow rate, which reduces speed and increases stops. The Auto LOS Model 2 uses two variables: Percent of Posted Speed Limit, and Median Type. C H A P T E R 9 Integrated Multimodal LOS Model Framework

93 Level of Service Auto Transit Bicycle Pedestrian A Best Performance Very Satisfied Best Performance Best Performance B C D E F Worst Performance Very Dissatisfied Worst Performance Worst Performance Exhibit 98. Definition of LOS by Mode. Inputs to LOS Models Facility Facility Transit Au to Transit Bic yc le Pedestria n Design Control Serv ice Volume Volume Volume Volume Au to LOS Model #1 Auto Stops (or Delay ) XXX XXX XXX XXX XXX Left Turn Lanes XXX Au to LOS Model #2 Mean Speed XXX XXX XXX XXX XXX Median Ty pe XXX Transit LOS Model Pedestrian LOS XXX XXX XXX XXX XXX Bus Headw ay XXX Bus Speed XXX XXX XXX XXX XXX Bus Schedule Adherence XXX XXX XXX XXX XXX Passenger Load XXX Bus Stop Amenities XXX Bicycle LOS Models Bike-Pedestrian Conflicts* XXX XXX XXX Drivew ay Conflicts/Mile XXX Vehicles Per Hour XXX XXX Vehicle Th rough Lanes XXX Auto Speed XXX XXX XXX XXX Percent Heavy Vehicles XXX XXX Pavement Condition XXX XXX XXX Width of Outside Lane XXX On-Street Parking Occupancy XXX XXX Cross Street Width XXX Pedestrian LOS Models Pedestrian Density XXX XXX Pedestrian-Bike Conflicts* XXX XXX XXX Width of Shoulder XXX Width of Outside Lane XXX On-Street Parking Occupancy XXX Presence of Trees XXX Sidew alk Width XXX Distance To Travel Lane XXX Vehicles Per Hour XXX XXX Vehicle Th rough Lanes XXX Average Vehicle Speed XXX XXX XXX XXX XXX XXX Right Turns On Red XXX XXX XXX XXX Cross Street Speed XXX XXX Cross Street Vehicles/Hour XXX XXX Cross Street Lanes XXX Crossing Delay XXX Right-T urn Channelization XXX Block Length XXX Signal Cy cle Length XXX XXX XXX XXX Signal Green Ti me XXX XXX XXX XXX “XXX” indicates that input variable is influenced by that factor. * Ped/bike conflicts come into play only for paths outside of roadway but within right-of-way of street. Exhibit 99. Interaction of Modal LOS Model Inputs.

• The Median Type is a facility design feature. • The percent of posted speed limit that traffic is able to travel the full length of the street is directly influenced by the in- tersection control type and the settings of the traffic signal. High auto and transit volumes can reduce the mean speed. Pedestrian and bicycle volumes at intersections reduce the saturation flow rate, which reduces mean auto speed. The Transit LOS Model uses 6 variables: Pedestrian LOS, Bus Headway, Bus Speed, Bus On-Time Performance, Pas- senger Load, and Bus Stop Amenities. • The pedestrian LOS is determined by the facility design, in- tersection controls, the volume of auto and transit traffic, and the pedestrian volume (pedestrian volumes influence signal timing, which affects signal delay for pedestrians, which affects pedestrian LOS). • The bus headway is determined by the transit service provider, which is related to the passenger loads. • Bus speed is determined by the facility controls (signal set- tings), the amount of auto and transit traffic, and the num- ber of boarding passengers at each stop. Bicycles in the travel lanes may delay buses. Heavy pedestrian volumes at intersections (or mid-block) may delay buses. • Bus on-time performance is determined by the service provider (e.g., number of back up buses, and maintenance to prevent breakdowns). It is also influenced by the auto, bicycle, and pedestrian volumes on the street. • Passenger load is determined by the density of development in the area, the relative convenience of other modes of travel, and the bus headways provided by the transit operator. • Bus stop amenities are a design feature of the facility. The Bicycle LOS Model uses the following variables: Drive- way Conflicts/Mile, Vehicles Per Hour, Vehicle Through Lanes, Speed Limit, Percent Heavy Vehicles, Pavement Condition, Width of Outside Lane, On-Street Parking Occu- pancy, and Cross Street Width. • Bicycle-Pedestrian Conflicts (only if bicycles share the pedestrian facility). • Driveway Conflicts/Mile are a design feature. • Vehicles Per Hour is determined by the auto, truck, and transit volumes. • Vehicle Through Lanes is a design feature of the facility. • Speed Limit is a control feature of the facility. It is influ- enced by the facility design. • Percent Heavy Vehicles is influenced by the auto, truck, and transit volumes. • Pavement Condition is a facility maintenance feature. It is influenced by auto, truck, and transit volumes and the pavement design. • Width Of Outside Lane is a design feature. • On-Street Parking Occupancy is determined by the park- ing controls, available off-street parking, and the density of land uses in the area. Facility design determines whether a parking lane is provided and whether or not parking is pro- hibited during peak hours. • Cross Street Width is determined by the facility design. The Pedestrian LOS Model uses the following variables: Pedestrian Density, Bicycle-Pedestrian Conflicts (if facility is shared), Width of Shoulder, Width of Outside Lane, On- Street Parking Occupancy, Presence of Trees, Sidewalk Width, Distance To Travel Lane, Vehicles Per Hour, Vehicle Through Lanes, Average Vehicle Speed, Right-Turns on Red, Cross Street Speed, Cross Street Vehicles/Hour, Cross Street Lanes, Crossing Delay, Right-Turn Channelization, Block Length, Signal Cycle Length, Signal Green Time • Pedestrian Density (Computed according to HCM). • Bicycle-Pedestrian Conflicts (only if bicycles share the pedestrian facility). • Width of Shoulder is a design feature. • Width of Outside Lane is a design feature • On-Street Parking Occupancy is determined by the park- ing controls, available off-street parking, and the density of land uses in the area. Facility design determines whether a parking lane is provided and whether or not parking is pro- hibited during peak hours. • Presence of Trees is a design feature. • Sidewalk Width is a design feature. • Distance to Travel Lane is a design feature. • Vehicles Per Hour is determined by the auto, truck, and transit volumes. • Vehicle Through Lanes is a design feature of the facility. • Average Vehicle Speed is determined by the facility design, the facility control (speed limit), and the auto, bus, bicycle, and pedestrian volumes on the facility, to the extent that bicycles and pedestrians share (or cross) the traveled way used by motor vehicles. • Right-Turns on Red are determined by the facility control (are they allowed?). They are influenced by the auto and transit volumes. Heavy pedestrian volumes may reduce the ability of autos or buses to turn right on red. • Cross Street Speed is determined by the design and control of the cross street. It is influenced by cross-street volumes. Heavy pedestrian or bicycle volumes may reduce the cross street speed. • Cross Street Vehicles/Hour is determined by the auto and transit volume. • Cross Street Lanes is a design feature. It is influenced by the auto and transit volumes. • Crossing Delay is determined by the intersection control (signal timing), which in turn is influenced by auto, bus, and pedestrian volumes. 94

• Right-Turn Channelization is a design feature. • Block Length is a design feature • Signal Cycle Length is a facility control feature. It is influ- enced by the facility design, auto and transit volumes, and the pedestrian volumes. • Signal Green Time is a facility control feature. It is influ- enced by the facility design, auto and transit volumes, and the pedestrian volumes. Interactions Among Modal LOS Results Exhibit 100 shows the major interactions among the input variable types, the modal LOS models, and the modal LOS model results. To estimate the variables required by the LOS models, the analyst first collects data on facility design, facility control, facility maintenance, transit service, and the volume for each mode. The analyst uses these data to esti- mate various modal performance characteristics (auto speed, bus speed, bus wait, bus access, bicycle-pedestrian conflicts if a shared facility is present, and pedestrian density). Once the modal performance characteristics are known, then the methods of NCHRP 3-70 are used to esti- mate auto LOS, transit LOS, bicycle LOS, and pedestrian LOS for the urban street. The bicycle-pedestrian conflict LOS is estimated using procedures in Chapters 18 and 19 of the HCM. 95 Auto LOS Transit LOS Bike LOS Ped LOS Facility Design Facility Control Mode Volumes Transit Service Auto Speed Si gn al T im in g Bu s He ad w a y La ne G eo m e try Au to /T ru ck s Bu s Bo ar di ng P as s. Bu s St op s Bus Speed Bus Wait Bus Access Facility Maint. Sp ee d Li m it Bi ke s Pe de st ria ns Ped Density Bi ke L an e Si de wa lk Pa ve m en t Bike-Ped Conflicts Tr ee s D el ay St op s Le ft Tu rn L an e Exhibit 100. LOS Model Interactions.

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Multimodal Level of Service Analysis for Urban Streets Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Report 616: Multimodal Level of Service Analysis for Urban Streets explores a method for assessing how well an urban street serves the needs of all of its users. The method for evaluating the multimodal level of service (MMLOS) estimates the auto, bus, bicycle, and pedestrian level of service on an urban street using a combination of readily available data and data normally gathered by an agency to assess auto and transit level of service. The MMLOS user’s guide was published as NCHRP Web-Only Document 128.

Errata

In the printed version of the report, equations 36 (pedestrian segment LOS) and 37 (pedestrian LOS for signalized intersections) on page 88 have been revised and are available online. The equations in the electronic (dpf) version of the report are correct.

In June 2010, TRB released NCHRP Web-Only Document 158: Field Test Results of the Multimodal Level of Service Analysis for Urban Streets (MMLOS) that explores the result of a field test of the MMLOS in 10 metropolitan areas in the United States.

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