Highway Capacity Manual Methodologies for Corridors Involving Freeways and Surface Streets (2020) / Chapter Skim
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From page 53... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 47 CHAPTER 38 SYSTEM ANALYSES (DRAFT)
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From page 54... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis INTRODUCTION Chapter 38 System Analyses (Draft) Page 48 Version 1.0 Evaluation of Off-Ramp Queue Spillback Impacts ..........................................
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 49 LIST OF EXHIBITS Exhibit 38-1 Off-Ramp Components ...........................................................................
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis INTRODUCTION Chapter 38 System Analyses (Draft) Page 50 Version 1.0 Exhibit 38-26 Input Data for Freeway Facility Analysis ...........................................
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 51 Exhibit 38-54 Freeway Facility (I-10 EB)
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis INTRODUCTION Chapter 38 System Analyses (Draft) Page 52 Version 1.0 Exhibit 38-76 Queue Accumulation Polygon for the On-Ramp β AWSC Intersection ............................................................................................................
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From page 59... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 53 Exhibit 38-A9 Freeway Facilities Oversaturated Segment Evaluation Procedure, Adapted for Off-Ramp Queue Spillback Evaluation - Continued ..............................................................................................................
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From page 60... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis INTRODUCTION Chapter 38 System Analyses (Draft) Page 54 Version 1.0 Exhibit 38-A30 Procedure for Evaluating the Impact of Queue Spillback on Upstream Nodes and Determination of the Queue Length within Upstream Segments ..............................................................................................
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From page 61... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 55 Exhibit 38-B14 Roundabouts Methodology With Adjustments to Address On-Ramp Queue Spillback ..................................................................................
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From page 62... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis INTRODUCTION Chapter 38 System Analyses (Draft) Page 56 Version 1.0 1.
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From page 63... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) INTRODUCTION Version 1.0 Page 57 β’ Chapters 16 and 18, which provide methodologies for evaluating urban street facilities and urban street segments, respectively, β’ Chapters 19, 20, 21, and 22, which provide analysis tools for signalized intersections, two-way stop-controlled intersections, all-way stopcontrolled intersections, and roundabouts, respectively, and β’ Chapter 23, which provides methods for evaluating ramp terminals and alternative intersections.
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From page 64... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Concepts Chapter 38 System Analyses (Draft) Page 58 Version 1.0 2.
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From page 65... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Concepts Version 1.0 Page 59 Queue spillback regimes The impact of queue spillback on the freeway mainline varies as a function of the queue length and the lanes blocked.
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From page 66... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Concepts Chapter 38 System Analyses (Draft) Page 60 Version 1.0 Under this regime, the queue blocks the rightmost lane, and drivers occasionally or often use the adjacent freeway mainline lane next to the rightmost freeway mainline lane to force their way into the queue, blocking thus an additional lane (Exhibit 38-2 (d)
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From page 67... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Concepts Version 1.0 Page 61 2 0.70 N/A 3 0.74 0.51 4 0.77 0.50 5 0.81 0.67 6 0.85 0.75 7 0.88 0.8 8 0.89 0.84 A Capacity Adjustment Factor (πΆπ΄πΉ )
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From page 68... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Concepts Chapter 38 System Analyses (Draft) Page 62 Version 1.0 SPILLBACK IMPACT ON URBAN STREETS Similar to spillback on freeways, spillback on urban streets may occur due to oversaturated conditions on freeways.
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From page 69... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Concepts Version 1.0 Page 63 LANE-BY-LANE ANALYSIS Spillback affects each lane of a facility differently.
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From page 70... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 64 Version 1.0 3.
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From page 71... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 65 β’ Expected travel speed along each segment System Analysis: β’ Total and free-flow travel times β’ Travel time index β’ Average speed Strengths of the Methodology The strengths of the methodology include: 1.
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From page 72... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 66 Version 1.0 REQUIRED DATA AND SOURCES The system analysis requires details concerning each freeway and urban street segment's geometric characteristics, as well as each segment's demand characteristics during each analysis time period.
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 67 ramp junctions with a lane drop.
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From page 74... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 68 Version 1.0 Step 1: Define Spatial and Temporal Analysis Scope The first step in the analysis requires identification of the spatial and temporal extent of the network to be evaluated.
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From page 75... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 69 Step 2: Provide Input Parameters for Freeway and Urban Street Analysis The urban street and freeway facilities are first modeled separately using the methodologies from the respective chapters.
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From page 76... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 70 Version 1.0 However, if the demand at the off-ramp exceeds its capacity, the flow that will reach the ramp terminal will be lower than the off-ramp demand vR.
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From page 77... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 71 π£ , = adjusted off-ramp demand (Equation 38- 1)
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From page 78... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 72 Version 1.0 π£ = on-ramp demand (veh/h)
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From page 79... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 73 interval.
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From page 80... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 74 Version 1.0 Appendix B details the calculations used to estimate the on-ramp demand based on the intersection operation as well as the procedures for conducting the on-ramp spillback check.
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From page 81... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 75 Step 5A: Compute Operating Speeds for Individual Lanes Along the Freeway Facility Along freeway facilities, operational performance is determined based on the density and speed at each segment along the network.
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From page 82... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 76 Version 1.0 For all segment types the share of flow is estimated on the mainline upstream of the segment.
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From page 83... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 77 where π = expected speed for the segment (mi/h)
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From page 84... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 78 Version 1.0 The travel time along freeway ramps is calculated by dividing the ramp length by its respective speed.
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 79 ramp roadway will increase until the limit value of jam density.
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From page 86... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 80 Version 1.0 Segment ID Segment Travel Time (s)
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 81 Performance measure Reference parameter Input value Freeway Facilities Lane flow ratio (LFR)
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From page 88... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis METHODOLOGY Chapter 38 System Analyses (Draft) Page 82 Version 1.0 π = control delay at the downstream intersection (s)
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From page 89... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) METHODOLOGY Version 1.0 Page 83 At free-flow conditions, the demand π£ is set at zero, which allows Equation 20-64 to be reduced to the following form: π = 3,600π , + 5 AWSC Intersections The control delay d for AWSC intersections is computed through Equation 21-30: π = π‘ + 900π π₯ β 1 + π₯ β 1 + β π₯450π + 5 where π‘ = service time (s)
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From page 90... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 84 Version 1.0 4.
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From page 91... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 85 When a freeway facility is analyzed in isolation, each on-ramp is a unique origin and each off-ramp is a unique destination.
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From page 92... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 86 Version 1.0 As shown in Exhibit 38-21, the system has 9 nodes and 72 O-Ds, shown in Exhibit 38-23.
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From page 93... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 87 the final travel time is obtained, its value will be checked and if it exceeds the 15minute study period the temporal scope of the study will be reevaluated.
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From page 94... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 88 Version 1.0 Intersection Parameter Eastbound Westbound Northbound Southbound L T R L T R L T R L T R Archer Rd.
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From page 95... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 89 β’ Yellow change interval: 4s; β’ Red clearance interval: 0s; and β’ No pedestrians.
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From page 96... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 90 Version 1.0 Segment Off-Ramp Demand (pc/h)
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Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 91 Parameter 2 (Williston Rd.)
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From page 98... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 92 Version 1.0 Segment ID Segment LOS Lane Flow Ratio (LFR)
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From page 99... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 93 Step 6 β Compute Travel Times for Each Segment The travel times for each segment in the freeway and urban street facilities are computed by dividing the segment length by the travel speed (Exhibit 38-39 and Exhibit 38-38)
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From page 100... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 94 Version 1.0 Facility Segment ID Travel time (s)
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From page 101... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 95 EXAMPLE PROBLEM 2: I-10 ON-RAMP SPILLBACK ANALYSIS IN BATON ROUGE, LOUISIANA This case study illustrates the application of the on-ramp spillback methodology by evaluating operations at an interchange when there is queue spillback originating from the on-ramp.
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From page 102... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 96 Version 1.0 The freeway facility (I-10 EB)
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From page 103... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 97 The analyzed urban street facility comprises four signalized intersections and three segments, as shown in Exhibit 38-44.
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From page 104... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 98 Version 1.0 The phasing sequence of the subject intersection is presented in Exhibit 3846.
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From page 105... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 99 Eastbound Northbound Southbound L T R T R L T General Information Base Sat.
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From page 106... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 100 Version 1.0 Segment ID Type Length (ft)
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From page 107... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 101 ET = equivalent number of through cars for a protected right-turning vehicle (1.18)
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From page 108... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 102 Version 1.0 during each phase as the product of the NBR saturation flow rate and the phase duration.
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From page 109... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 103 Time Period Parameter Movements EBT NBR SBL 1 Demand (veh/h)
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From page 110... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 104 Version 1.0 Time period Seg 1 Seg 2 Seg 3 Seg 4 Seg 5 Seg 6 Seg 7 B D D B M B B 1 D C D C D D D 2 E F F F F F E 3 D D F F F E E 4 D C C B C C C Segment type: B: basic; D: diverge; M: merge The next step will estimate the on-ramp queue length compared to the available queue storage length to determine whether spillback is expected to occur.
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From page 111... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 105 Step 7B β Obtain merging capacity with Freeway Facilities method When the freeway facility operates in oversaturated conditions, the capacity of the subject merge section may be constrained by the presence of queues along the mainline.
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From page 112... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 106 Version 1.0 Seg 5 (Merge)
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From page 113... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 107 The cycle starts with a permitted left-turn movement (Ξ¦1: SBL)
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From page 114... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 108 Version 1.0 where sSBL = saturation flow rate of the SBL movement (veh/h/ln)
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From page 115... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 109 extension(veh/h/ln)
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From page 116... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 110 Version 1.0 restricted to the permitted saturation flow rate, causing queues to develop in the NBR approach.
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From page 117... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 111 Time Period 3 The same steps performed for the analysis of time period 2 are applied again for the analysis of time period 3.
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From page 118... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 112 Version 1.0 Queue spillback occurs during the third cycle (SBL queue service time)
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From page 119... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 113 The procedure is then repeated for the remaining movements of the cycle, as shown in Exhibit 38-62.
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From page 120... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 114 Version 1.0 respectively, by their duration.
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From page 121... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 115 The merge capacity for time period 4 has been previously determined, as shown in Exhibit 38-57a.
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From page 122... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 116 Version 1.0 Cycle Active phase Duration (s)
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From page 123... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 117 Time Period Movement capacity (veh/h)
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From page 124... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 118 Version 1.0 EXAMPLE PROBLEM 2, PART 2: TWSC RAMP TERMINAL This scenario study will replace the signalized intersection from Part 1 with a TWSC intersection, while keeping the freeway facility characteristics unchanged.
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From page 125... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 119 Different from the signalized intersection scenario, there are no conflicting flows to the unsignalized right turn since it is a Rank 1 movement (highest priority)
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From page 126... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 120 Version 1.0 β’ Time periods 2 and 3: 1,142 veh β’ Time period 4: 1,142 veh/h during 4 time steps (60 seconds)
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From page 127... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 121 Step 10.
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From page 128... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 122 Version 1.0 With the adjusted capacity values obtained, the performance measures for the intersection can be computed using the next step from the TWSC methodology (Chapter 20)
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From page 129... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 123 EXAMPLE PROBLEM 2, PART 3: AWSC INTERSECTION RAMP TERMINAL This scenario will replace the signalized intersection from Part 1 with an AWSC intersection, while keeping the freeway facility characteristics unchanged.
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From page 130... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 124 Version 1.0 Time Period Parameter Movements EBT NBR SBL 1 Demand (veh/h)
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From page 131... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 125 Step 13B - Obtain merging capacity with Freeway Facilities method For this example, the ramp metering rate (900 veh/h)
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From page 132... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 126 Version 1.0 Movement Capacity during spillback (csp)
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From page 133... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 127 EXAMPLE PROBLEM 3: OFF-RAMP QUEUE SPILLBACK ANALYSIS FOR A FREEWAY-TO-FREEWAY RAMP IN MIAMI, FLORIDA.
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From page 134... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 128 Version 1.0 Input data Traffic demands for the freeway facilities and ramps are provided in Exhibit 38-1 in 15-minute time periods.
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From page 135... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 129 β’ Acceleration lane length: 1500 ft; β’ No shoulder available; β’ Deceleration lane length: 700 ft; β’ Number of ramp lanes: 2; and β’ Familiar facility users.
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From page 136... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 130 Version 1.0 Time period Total number of queued vehicles Number of queued vehicles in each lane Average vehicle spacing (ft)
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From page 137... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 131 The unblocked background density KBUB is calculated next.
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From page 138... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 132 Version 1.0 The initial number of vehicles in the ramp is then computed as: π
ππ 3,0,2,1 = 37.4 Γ 35885280 Γ 2 = 50.8 ππ Step 2G - Determine the capacity of the downstream terminal The capacity of the merge is obtained by analyzing the downstream freeway facility using the oversaturated segment evaluation procedure and aggregating the parameter ONRO for an hourly flow rate.
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From page 139... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 133 Since spillback does not occur, no additional calculations for the mainline are required.
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From page 140... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 134 Version 1.0 After the onset of queue spillback, the number of unserved vehicles at the exit is computed every time step through the parameter OFRUV(i,t,p)
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From page 141... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 135 β’ 0 < OFRLQ β€ 1,400 ft: Regime 1 β’ 1400 ft < OFRLQ β€ 3000 ft: Regime 4, with increased turbulence β’ 3000 ft < OFRLQ: Regime 4, with lane blockage (queue extends upstream beyond the diverge)
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From page 142... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 136 Version 1.0 For the freeway facility, performance measures are computed for the blocked and unblocked portions of each segment.
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From page 143... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 137 EXAMPLE PROBLEM 4: ON-RAMP QUEUE SPILLBACK ANALYSIS INTO A SINGLE-LANE ROUNDABOUT IN LOS ANGELES, CALIFORNIA This example problem illustrates the analysis methodology when there is spillback from an on-ramp into a single-lane roundabout.
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From page 144... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 138 Version 1.0 π£ , , = 0 ππ/β π£ , , = 300 ππ/β Step 4: Determine Entry Flow Rates per Approach The entry flow rate at each approach is calculated by adding the movement flow rates that enter the roundabout.
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From page 145... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 139 π , = 121 π£πβ These values are rounded to the nearest vehicle.
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From page 146... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 140 Version 1.0 β = departure saturation headway into the on-ramp (s/veh)
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From page 147... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 141 Step 15: On-Ramp Metering Capacity Once the saturation flow rate at the exit leg towards the on-ramp is calculated, given the metering rate, the maximum exit flow rate into the on-ramp is: π , = πππ π , 3600β = πππ 800, 3,6002.77 = 800 ππ/β Step 16: On-Ramp Storage Ratio and Queue Spillback Length The on-ramp storage LONR is calculated in passenger cars, considering an average spacing of 25 ft, and given that the total length of the ramp is 1657 ft: πΏ = 1,65725 = 66 ππ With the maximum exit flow rate into the on-ramp, the number of vehicles that exit the roundabout through the on-ramp during a 15-minute period analysis is obtained by the difference between the on-ramp throughput Ξ» , and the ramp metering rate cRM: π = π , β π4 = 1234 β 8004 = 108 ππ The queue storage ratio RQ is then calculated as the ratio between the expected queue and the on-ramp storage: R = ππΏ = 10866 = 1.63 Since RQ > 1.0, there will be queues on each approach due to spillback.
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From page 148... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Example Problems Chapter 38 System Analyses (Draft) Page 142 Version 1.0 π = 36001380 + 900(0.25)
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From page 149... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Example Problems Version 1.0 Page 143 5.
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From page 150... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 144 Version 1.0 APPENDIX A: OFF-RAMP QUEUE SPILLBACK ANALYSIS Chapter 10, Freeway Facilities evaluates the performance of each segment individually using standard 15-minute time periods.
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From page 151... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 145 Case A: Ramp Roadway Demand at the study diverge ramp (π£ , as defined in Chapter 14)
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From page 152... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 146 Version 1.0 described in Chapter 25, Freeway Facilities Supplemental)
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From page 153... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 147 Case B: Ramp Terminal Spillback occurs when the resulting queues from the downstream ramp terminal intersection exceeds the available ramp storage.
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From page 154... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 148 Version 1.0 likely choose the rightmost lane (Ramp Lane 2)
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From page 155... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 149 the demand difference among ramp lanes can be considered negligible for the purposes of this analysis.
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From page 156... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 150 Version 1.0 where π = number of lanes in section π; and πΏ = length in section π (ft)
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From page 157... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 151 Case C: Downstream Merge The queue storage ratio for freeway-to-freeway connections is estimated as follows: π
= π Γ πΏπΏ π where π = downstream on-ramp queue length (veh)
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From page 158... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 152 Version 1.0 EVALUATION OF OFF-RAMP QUEUE SPILLBACK IMPACTS Chapter 14 provides three LOS checks for diverge segments, and failure (LOS F)
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From page 159... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 153 The geometry of an off-ramp is seldom a homogenous road segment, and additional lanes are frequently added closer to the arterial intersection approach.
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From page 160... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 154 Version 1.0 are assumed to develop or discharge linearly based on the relationship between demand and capacity.
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From page 161... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 155 Glossary of variable definitions This glossary defines internal variables used in the methodology for offramp queue spillback evaluation.
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From page 162... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 156 Version 1.0 β’ OFRLQ(i,t,p)
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From page 163... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 157 β’ MO2BL(i,t,p)
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From page 164... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 158 Version 1.0 Intersection (ramp terminal)
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From page 165... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 159 Evaluation of operations on the freeway mainline: step-by-step methodology description The methodology for evaluating off-ramp queue spillback is integrated to the core methodology for Freeway Facilities Oversaturated Segment Evaluation (HCM Chapter 25)
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From page 166... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 160 Version 1.0 Exhibit 38-A9 Freeway Facilities Oversaturated Segment Evaluation Procedure, Adapted for Off-Ramp Queue Spillback Evaluation - Continued
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From page 167... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 161 Exhibit 38-A10 Freeway Facilities Oversaturated Segment Evaluation Procedure, Adapted for Off-Ramp Queue Spillback Evaluation - Continued
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From page 168... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 162 Version 1.0 Exhibit 38-A11 Freeway Facilities Oversaturated Segment Evaluation Procedure, Adapted for Off-Ramp Queue Spillback Evaluation - Continued
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From page 169... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 163 Step 1 - Calculate background density for unblocked lanes on each segment in the case of queue spillback The first step in the Oversaturated Segment Evaluation procedure computes a background density (KB)
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From page 170... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 164 Version 1.0 When Regime 4 occurs (2 blocked lanes)
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From page 171... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 165 The analyst should select one of these two regimes based on prevailing driver behavior at the site and in the vicinity of the site.
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From page 172... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 166 Version 1.0 Exhibit 38-A6.
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From page 173... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 167 Example 3 β A two-lane ramp connects with a signalized intersection ramp terminal (Exhibit 38-A18)
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From page 174... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 168 Version 1.0 behavior.
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From page 175... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 169 undersaturated off-ramps, where signing and navigation information is provided in advance and allows drivers to adjust their position earlier.
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From page 176... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 170 Version 1.0 The ramp density at capacity (RKC)
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From page 177... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 171 Step 2F - Determine initial number of vehicles at the off-ramp The computation of the number of vehicles in the facility at every time step is critical for deriving performance measures of oversaturated freeway facilities.
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From page 178... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 172 Version 1.0 right side of the barrier (Exhibit 38-A26)
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From page 179... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 173 Input Parameters The required parameters to evaluate the capacity of a ramp terminal capacity are generally the same required for standard signalized intersection analyses, as listed in Exhibit 19-11.
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From page 180... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 174 Version 1.0 the difference is included in the first time-step of the next cycle.
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From page 181... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 175 Exhibit 38-A29, where the node (i+2)
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From page 182... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 176 Version 1.0 π
πΉ(π, π‘,π)
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From page 183... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 177 takes into account the off-ramp flow RF and the number of unserved vehicles on the approach from the previous time step IUV.
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From page 184... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 178 Version 1.0 πΌπ(π, π‘,π, π)
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From page 185... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 179 length of the queue in the upstream segment.
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From page 186... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 180 Version 1.0 2.
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From page 187... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 181 The parameter LCR estimates the rate of lane change maneuvers performed by vehicles within the Queue Influence Area trying to adjust their position when spillback occurs.
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From page 188... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 182 Version 1.0 The value of pi as function of the distance from off-ramp exit can then be obtained through the following equation: π = π , + 1π β π ,π
Γ (π β 1,500)
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From page 189... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 183 Step 9 - Calculate mainline input The Oversaturated Segment Evaluation procedure computes the Mainline Input (MI)
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From page 190... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 184 Version 1.0 If one or more lanes are blocked due to a downstream off-ramp bottleneck, the throughput in Lane 1 will be equal to the maximum exit throughput in the congested off-ramp if the site operates in Regime 3, or 50% of the maximum exit throughput in the off-ramp, if it operates in Regime 4.
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From page 191... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 185 ππ2ππ΅(π, π‘,π)
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From page 192... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix A: Off-ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 186 Version 1.0 component MFUB represents flow across the node in the unblocked lanes, while the component MFBL represents the flow across the node in the blocked lanes.
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From page 193... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix A: Off-ramp Queue Spillback Analysis Version 1.0 Page 187 π
πΉ(π,π, π)
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From page 194... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 188 Version 1.0 APPENDIX B: ON-RAMP QUEUE SPILLBACK ANALYSIS Queue spillback into an urban street intersection may occur when the freeway merge segment has insufficient capacity to process the ramp's demand.
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From page 195... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 189 DEMAND ESTIMATION The first step in the methodology calculates the entering demand flow rate at the on-ramp (π£ )
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From page 196... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 190 Version 1.0 π = π π π π π π π π π π π π π π Where π = saturation flow rate for unsignalized movement during free-flow (veh/h/ln)
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From page 197... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 191 according to their ranks, using the default numbering of Chapter 20 (Exhibit 201)
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From page 198... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 192 Version 1.0 3.
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From page 199... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 193 The on-ramp demand flow rate can be obtained directly from the departure headways of the three movements combined: π£ = 3600β , + 3600β , + 3600β , where π£ = on-ramp flow rate (veh/h)
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From page 200... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 194 Version 1.0 Rank 1 Movement (Left-Turn from the Third Upstream Approach from the OnRamp)
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From page 201... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 195 π£ = π + π + π The total on-ramp demand flow rate can be calculated by the same method for roundabouts with a higher number of approaches.
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From page 202... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 196 Version 1.0 EVALUATION OF ON-RAMP QUEUE SPILLBACK IMPACTS This section describes the methodological modifications required to address the occurrence of queue spillback from an on-ramp.
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From page 203... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 197 Step 7A - Determine intersection throughput to on-ramp The volume of vehicles that enters a freeway on-ramp is a function of the demands and capacities of each individual intersection movements that discharge into the ramp.
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From page 204... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 198 Version 1.0 The total throughput from the intersection into the on-ramp Ξ»ONR is the sum of the throughput from each of the contributing movements: π = π + π + π The throughput for each movement i is the minimum value of its demand and capacity: π = πππ(π£ , π )
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From page 205... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 199 to evaluate whether the merging capacity is constrained by oversaturated conditions in the mainline.
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From page 206... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 200 Version 1.0 Step 7C.
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From page 207... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 201 maintained and it is equal to LONR until the end of the green for the SBL movement.
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From page 208... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 202 Version 1.0 movement cSBL,SP can be obtained from the QAP as the slope of the red line (cSBL,SP - cmerge)
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From page 209... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 203 π = π£π Two-Way Stop-Controlled (TWSC)
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From page 210... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 204 Version 1.0 Step 9A - Determine intersection throughput to on-ramp The throughput to the on-ramp is calculated using the approach described in Step 7A of the queue spillback analysis for signalized intersections (Exhibit 38B5)
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From page 211... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 205 i discharging into the on-ramp, the throughput is the minimum value of its demand and its movement capacity: π = πππ π£ , π , where vi = demand flow rate for movement i cm,j = movement capacity for movement i (Equations 20-36, 20-37 and 20-40)
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From page 212... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 206 Version 1.0 π = π β πΏ β π(0)
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From page 213... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 207 C , = capacity during spillback for movement i (veh/h)
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From page 214... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 208 Version 1.0 ALL-WAY STOP-CONTROLLED (AWSC)
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From page 215... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 209 paragraphs.
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From page 216... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 210 Version 1.0 Required Data and Units Potential Data Source Suggested Default Onramp Data On-ramp metering rate (veh/h)
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From page 217... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 211 where Ξ»SB-ONR = departure rate from the SB approach into the on-ramp (veh/h)
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From page 218... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix B: On-Ramp Queue Spillback Analysis Chapter 38 System Analyses (Draft) Page 212 Version 1.0 Step 14 β Calculate the throughput into the on-ramp The maximum throughput from the roundabout to the on-ramp, π is calculated as: π = π + π + π Step 15 β Compute on-ramp merging capacity and compare to the maximum throughput to the on-ramp The calculation of the on-ramp merging capacity follows the exact same procedure used in Step 7B of the methodology developed for queue spillback into Signalized Intersections (Exhibit 38-B5)
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From page 219... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix B: On-Ramp Queue Spillback Analysis Version 1.0 Page 213 π , = π Γ π π + π , π , = π Γ π π + π , π , = π Γ π π + π , Where π , = queue due to the on-ramp spillback on π approach (veh)
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From page 220... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 214 Version 1.0 APPENDIX C: LANE-BY-LANE ANALYSIS FOR FREEWAY FACILITIES LANE-BY-LANE FLOW MODELS BY SEGMENT TYPE The lane flow ratio (LFR)
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From page 221... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 215 π = empirical constant (Exhibit 38-C1)
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From page 222... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 216 Version 1.0 π = empirical coefficient for volume ratio (Exhibit 38-C2)
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From page 223... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 217 Parameter 2-Lane Segments 3-Lane Segments 4-Lane Segments L1 L1 L2 L1 L2 L3 π 0.99 0.64 0.48 -0.13 0.0048 0.12 π 0.40 0.40 0.33 0.24 0.26 0.27 π -0.21 -0.28 0.11 0.13 -0.0048 -0.12 π -0.12 -0.055 -0.033 -0.012 -0.0048 0.019 π 0.13 0.0037 -0.035 -0.0025 -0.0048 -0.12 π 0.022 0.075 -0.090 0.072 -0.031 -0.011 π -0.19 -0.036 0.017 -0.13 0.030 0.051 π -0.20 0.098 -0.031 0.056 0.0020 -0.041 π 0.0080 0.024 0.089 -0.11 -0.0045 0.12 π 0.069 -0.40 0.039 -0.030 0.045 0.041 π 0.0032 -0.051 0.0045 -0.0043 -0.011 -0.0043 π -0.016 0.40 -0.020 -0.0067 -0.0050 -0.0026 π -0.048 -0.14 0.0047 0.065 -0.0089 -0.038 π 0.040 0.039 -0.047 0.063 -0.015 -0.037 π -0.011 0.15 0.0050 -0.030 0.011 0.020 π 0.078 0.40 0.018 -0.14 0.040 0.15 Notes: The number of lanes parameter represents the freeway section upstream of the weave.
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From page 224... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 218 Version 1.0 Next, Exhibit 38-C4 illustrates the LFR distribution for a 3-lane freeway segment.
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From page 225... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 219 factors such as ramp volume, grade, truck percentage influence the boundary values and slopes of the curves, but does not change the typical LFR distribution as function of v/c.
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From page 226... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 220 Version 1.0 The variables in Exhibit 38-C7 are defined as follows: π = index for the subject lane; π = capacity for lane i; π£ = flow rate on lane i; β = exceeding flow on lane i, to be relocated to the adjacent lane π = number of lanes in the segment SPEED FLOW CURVES BY LANE AND BY SEGMENT TYPE This section presents the models used to obtain speed-flow curves for each lane in a freeway segment, as a function of two key inputs: free-flow speed (FFS)
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From page 227... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 221 Segment Type Number of Lanes FFS Multiplier (xFFS)
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From page 228... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 222 Version 1.0 Segment Type Number of Lanes Capacity Multiplier (xc)
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From page 229... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 223 πΉπΉπ = free-flow speed on lane i(mi/h)
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From page 230... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 224 Version 1.0 APPLICATION EXAMPLES Example 1 - Diverge Segment from Example Problem 1 This section presents an application of the LFR model for a freeway segment extracted from Example Problem 1 (O-D Based Travel Time Estimation for I-75 NB Freeway in Gainesville, FL)
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From page 231... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 225 π = 0.0096 + 1 Γ (β0.00960)
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From page 232... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 226 Version 1.0 π = πΉπΉπ β πΉπΉπ β π45 (π£ β π΅π )
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From page 233... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 227 β’ Interchange density (πΌπ·)
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From page 234... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 228 Version 1.0 πβ² = 2,400 β [438.2(1 + 0.325)
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From page 235... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 229 π = 0.0176 π = π + πΊ Γ π + π‘ Γ π + πΌπ· Γ π + π£ ,1000 Γ π + π£ ,1000 Γ π + πΏ1000 Γ π+ ππ
Γ π π = 0.26 + (β0.5)
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From page 236... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Appendix C: Lane-by-Lane Analysis for freeway facilities Chapter 38 System Analyses (Draft) Page 230 Version 1.0 β’ Grade: 3% (rolling)
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From page 237... ...
Highway Capacity Manual: A Guide for Multimodal Mobility Analysis Chapter 38 System Analyses (Draft) Appendix C: Lane-by-Lane Analysis for freeway facilities Version 1.0 Page 231 As observed, the individual speed-flow models can replicate field conditions with good accuracy.
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