Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles (2018) / Chapter Skim
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Pages 91-111
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91 This chapter expands on the detailed analysis results produced by the simulations. This chapter organizes the analysis results in terms of the sensitivity parameters that were assessed as part of the evaluation.
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92 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles implemented as exclusive lane use at MPRs higher than 25%. At lower market penetration (10%)
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Evaluation Results 93 Figure 6.1. Comparison of DSH performance measures with and without exclusive DL access.
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94 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles 6.2 Impact of Market Penetration In this analysis, the project team reviewed the impact of market penetration on network performance when dedicating lanes to CAVs. 6.2.1 CACC When assessing the CACC application, it was found that at lower market penetration, sharing lanes with HOVs would prevent oversaturation of GPLs.
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Evaluation Results 95 DLs with HOVs can decrease the throughput by almost 60%. The latter result arises primarily because fewer vehicles are allowed on the DLs.
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96 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles Figure 6.5 shows that the fuel consumption and emissions reduce as a function of market penetration, with most of the benefits being received at 35% market penetration or higher. 6.2.2 DSH A similar assessment was performed for DSH.
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Evaluation Results 97 Figure 6.7. Speed contours for I-66 westbound direction under differing DSH market penetrations.
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98 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles improved the throughput by about 2%. The throughput improvements were assessed under the same overall demand.
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Evaluation Results 99 throughout the freeway. As shown, at 10% market penetration, there is a significant reduction in throughput, averaging 9%.
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100 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles 6.4.1 CACC The impact of reduced and increased demand was assessed in relation to the CACC application at 10% market penetration. As was found in the previous analysis, to avoid disparate lane utilization, sharing lanes with HOVs was warranted at 10% market penetration.
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Evaluation Results 101 conditions, the improvement in throughput was even higher, with benefits between 3% and 4% at any given time. The percentage benefits for each scenario are demonstrated in relation to the base case at the respective demand levels, not at the normal demand.
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102 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles speeds of equipped vehicles over the entire freeway to reduce shockwaves. However, when there was reduced demand, the DSH application had marginal impact, because there were no congested areas in the network.
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Evaluation Results 103 6.5 Impact of Access Restrictions One of the research questions aimed to compare the impacts of dedicating lanes to CAV users when access restrictions to the DL exist. This section describes the impacts of continuous versus restricted access to DLs using the primary case study site, the I-66 corridor.
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104 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles Several performance measures were collected during the simulation, but the following performance measures were highlighted to develop conclusions about DL access settings: • Change in Average Network Travel Time. This measure showed the network-wide mobility impacts of CACC and the CACC+DSH combination as a comparison with the base case -- HOV DLs with continuous access.
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Evaluation Results 105 incidents were modeled in the simulation network to observe the effects of a static bottleneck on freeway operations on I-66. The location and duration of the modeled incident was developed using historical data and empirical observations derived from the Transportation Technical Report: Interstate 66 – From US Route 15 in Prince William County to Interstate 495 in Fairfax County, published in February 2013 (Virginia DOT, Virginia DRPT, and FHWA 2013)
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106 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles be seen in the benefits obtained from both CACC and DSH DLs. For the CACC application -- represented in the figure as (a)
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Evaluation Results 107 team modeled a scenario to replicate this situation. Such a situation could arise from many factors, such as a slow driver, a heavy vehicle that cannot perform at a faster speed, a maintenance vehicle performing maintenance, and so forth.
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108 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles Figure 6.19 shows the difference in vehicle throughput with respect to the baseline scenario in two situations: (a) without the moving bottleneck and (b)
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Evaluation Results 109 theoretical throughput of the lanes, the actual number of vehicles released into the simulation was constrained by the "present-day" demand. Analysis at a macroscopic scale is required to understand the impact on the demands on transportation systems with the advent of CAV technology.
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110 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles were seen in terms of reductions in travel time as well as increases in throughput when CACC market penetration was greater than 25%. With higher demand, however, the research team observed much greater benefits even at a lower market penetration.
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Evaluation Results 111 drives the computation to compare the economic benefits of one category of users over the other. The following assumptions were used in this analysis: • Computation Driver: Average observed travel speeds of DL (vDL)
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