Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles (2018) / Chapter Skim
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Pages 122-131
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From page 122... ...
122 Based on the analysis described in the previous chapters, the project team developed guidance for agencies regarding dedicating lanes to CAVs. The guidance provided in this chapter related to the operational characteristics and impacts of dedicating lanes to CAVs are representative of the scenarios that were explicitly modeled in this project, and may not be representative of a wider range of scenarios.
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From page 123... ...
Guidance on Operational Characteristics and Impacts 123 As the market penetration of CACC-equipped vehicles increases beyond 45%, mobility benefits will likely occur even without dedicating lanes to CAVs. Significantly, the project team did not model scenarios in which more than one DL was provided for exclusive use by CAVs.
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From page 124... ...
124 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles illustrates the benefits and disbenefits to users of DLs and GPLs when CACC-equipped vehicles have shared or exclusive access to DLs. The actual increase in person-throughput would differ from the vehicle throughput, because CACC-equipped vehicles might be SOVs, whereas the baseline DL usage was exclusive to HOVs.
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From page 125... ...
Guidance on Operational Characteristics and Impacts 125 and environmental performance of both sets of users. At still higher market penetration levels, dedicating additional lanes for use by the CACC-equipped vehicles provides additional benefits when the number of dedicated lanes is well matched to the market penetration so that all lanes are well utilized.
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From page 126... ...
126 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles As far as system-wide benefits are concerned, there is some benefit when DSH-equipped vehicles share the DLs with HOVs at lower market penetration, and when DSH-equipped vehicles have exclusive lane access in the case of higher market penetrations. For market penetrations higher than 25%, safety-related benefits are demonstrated when no DLs are used.
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From page 127... ...
Guidance on Operational Characteristics and Impacts 127 When CACC was assessed for the US-101 corridor, increasing traffic beyond typical peak traffic did not cause further increase in throughput. This result was primarily due to the fact that the US-101 traffic density was already approaching saturation at typical peak traffic conditions.
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From page 128... ...
128 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles • Low Market Penetration of CAV with Exclusive DLs. This group showed the highest lane frictions, on the order of 30 mph.
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From page 129... ...
Guidance on Operational Characteristics and Impacts 129 As they begin to contemplate dedicating lanes for CAVs, state and local DOTs, metropolitan planning organizations, and infrastructure owners and operators are trying to determine what CV infrastructure needs to be deployed, where to deploy it, and when to deploy it. Furthermore, these agencies are struggling with the issue of how to fund and/or finance this deployment.
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From page 130... ...
130 Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles For the foreseeable future, the large majority of CAVs that could potentially benefit from dedicated lanes will be at the lower levels of automation, with SAE Level 1 and Level 2 driving automation systems, so there is no reason to discriminate among levels of automation in determining which vehicles should have access to the DLs. Rather, the important criterion for DL access should be the use of connectivity, because the concentration of connected vehicles in the DL is the fundamental way of gaining benefits.
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From page 131... ...
Guidance on Operational Characteristics and Impacts 131 Public opinions are still being formed and are at a volatile stage as the boundaries between imagination and reality become more clearly defined in the public mind. The initial "hype" period will likely yield to a more realistic assessment of opportunities and risks, especially in light of the early 2018 crash of an automated Uber vehicle (Bliss 2018)
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