Macro / Meso / Micro Framework on I-395 HOT Lane Conversion
Corresponding Author: Scott Thompson-Graves, Whitman, Requardt, and Associates
Presented By: Jeffrey Moore, Whitman, Requardt & Associates, LLP
One of the challenges of advancing projects in highly congested areas is producing project-specific measures of effectiveness which are meaningful while meeting project deadlines. This was the case for the proposed conversion of the HOV lanes on I-395 from the I-495 beltway to Washington, D.C. to High Occupancy Toll Lanes. This area experiences over-saturated conditions through most of the day, which cause distinct challenges to determining the actual demand for travel since traffic counts do not account for the true hourly demand but rather are an indicator of the capacity of the roadway.
Standard macroscopic approaches to producing travel forecasts and traditional measures of level of service are often inadequate to evaluate the realistic impacts of projects such as these on congestion relief. This presentation will highlight an approach which combined a regional travel demand model, a post processor to incorporate toll diversion curves, and a fine-grained model which used ODME to estimate detailed forecasts within the study area for multiple hour peak periods to produce travel forecasts. These high-resolution forecasts were combined with a two-tiered approach to evaluating project benefits, the first used mesoscopic simulation to produce the project impacts for the environmental assessment while a detailed microsimulation model was developed for the interchange modification report. This approach was able to meet the project needs while meeting the project schedule.