Conversion of an HOV lane to a HOT lane with dynamic congestion responsive tolling - an Active Transportation and Demand Management (ATDM) Strategy.
Nationwide, United States
Guide for Highway Capacity and Operations Analysis of Active Transportation and Demand Management Strategies
Summary Information
This document provides methodologies and measures of effectiveness for evaluating the impacts of Active Transportation and Demand Management (ATDM) strategies on highway and street system demand, capacity, and performance as related to the Highway Capacity Manuel (HCM). Included in this guidance is an example application of the ATDM analysis methodology with congestion pricing. The example’s study site is a 7.6-mile-long section of a three-lane freeway and the study period is the 4-hour weekday PM peak period. Analysis of the site suggests there might be spare capacity in the HOV that could be used during peak periods of high congestion (the maximum HOV demand is 1,350 vph while a target capacity of 1,600 vph would be available for a HOT lane; although the operating capacity would later be discounted to 1,500 vph to allow for some inefficiencies in the toll setting process).
Methodology:
The HOV/HOT lane conversion strategy assumes that the toll will be dynamically set as low as necessary to equalize demand across all lanes until the HOT lane's capacity is reached.
The following sampling scheme is employed for selecting 30 operational scenarios:
- Three demand levels (low, medium, high)
- Three weather types (clear, medium rain, light snow)
- Two incident types (no incident, property damage only crash blocking one lane)
- Two work zone types (No work zone, Long-Term maintaining 3 lanes open)
For the "before data", scenario-specific demand, free-flow speed, and capacity adjustment factors are input into the selected HCM analysis tool (in this case, FREEVAL-ATDM). Lane closure data for incidents and work zones is also input. The HCM analysis tool is applied 30 times.
For the "after data", the scenario-specific capacity adjustment factors for the conversion from HOV to HOT lanes are input into FREEVAL-ATDM. The HCM analysis tool is reapplied to the original 30 scenarios, but this time with capacity adjustment factors tailored to HOT lane operation rather than HOV lane.
Findings
- Converting the HOV lane to HOT lane operation results in a 7 percent reduction in annual vehicle-hours traveled, a 22 percent reduction in annual vehicle hours of delay and a 7 percent increase in mean speed on the facility during the PM peak period. The average delay per mile is reduced 22 percent and the Planning Time Index is decreased by 16 percent.
- The HOT lane enables the freeway to serve 100 percent of the VMT demand.
- The improvements are greatest where the greatest congestion was present in the before conditions, however; all scenarios see better performance with the HOT lane.
