Methodology

The study area encompassed nine major roadways in Suffolk County, including three county roads, five state routes, and the Long Island Expressway (I-495). The trip pattern information from the New York Metropolitan Transportation Council Best Practice Model was supplemented by detailed turning movement counts obtained from a traffic data vendor to ensure the use of up-to-date traffic data. In addition, the extensive historical data available from the DFE was used to identify incident scenarios. The benefits of applying ICM response plans to selected incident scenarios on I-495 were evaluated using microscopic traffic simulation. Three incident scenarios were created in the model, and cases were run with and without response plans. The plans included using Variable Message Signs (VMS) to notify the road users, informing driving and decision-making via commonly used navigation apps, and modified traffic signal timing plans and use of enforcement personnel to handle detoured traffic. The analysis periods were focused on the weekday AM and PM peak periods on and around I-495 and service roads.

Findings

• Based on the simulation results, the average time to travel the entire corridor was lower when the response plan was applied compared to the no action case. The improvement ranged from 17.2 to 48.9 percent, depending on the incident scenario and whether comparing the mainline or service road travel time.
• Simulation cases where response plans were executed provided a travel time improvement that was in the range of 30–40 percent on average, and as much as 100 minutes for one service road trip scenario.