Simulation Analysis of a Congested Corridor Finds 6 Percent Reduction in Travel Time Costs through a Combination of Freight and Transit Signal Priority.

Results from a Microsimulation Case Study of Freight and Transit Priority Strategies on Sunrise Boulevard in Fort Lauderdale, Florida.

Date Posted

02/24/2021

Fort Lauderdale, Florida, United States

Fort Lauderdale, Florida,

United States

Identifier

2021-B01533

Evaluation of Freight and Transit Signal Priority Strategies in Multi-Modal Corridor for Improving Transit Service Reliability and Efficiency

Summary Information

Dynamics of trucks and transit vehicles on a signalized corridor can lead to suboptimal results due to factors such as low acceleration/deceleration rates, long vehicle lengths, and higher emissions. One solution to help improve operations is selective provision of priority treatments at traffic signals, known as Freight Signal Priority (FSP) for trucks and Transit Signal Priority (TSP) for transit vehicles. These strategies use sensors or communications technologies to detect certain vehicles approaching an intersection or along a corridor, and enable adjustments to the signal timing based on defined factors and conditions. For example, by extending the green interval to allow an approaching truck to pass the intersection, delay and other impacts due to deceleration and acceleration may be reduced.

Methodology

The goal of the project was to assess various strategies to provide FSP and TSP without deteriorating the traffic conditions of the overall network. The effectiveness of the strategies was assessed using microscopic simulation of a 4.4-mile congested corridor on Sunrise Boulevard in Fort Lauderdale which includes significant freight and transit traffic and 22 signalized intersections. In total, seven scenarios providing FSP, TSP, or a combination of the strategies, were modeled along with a base scenario reflecting the existing conditions. Travel time was the primary measure used, and in addition, researchers assigned dollar values of time and average vehicle occupancy to support an overall comparison.

Findings

All the FSP and TSP scenarios presented a positive effect on the freight and transit movements on the main street.
The travel time and delays were reduced significantly on the majority of the corridor’s main street segments, with a few exceptions related to the road geometry.
The side street impacts differed depending on the strategy applied. Unconditional freight priority resulted in a significant increase in side street delay on streets with high volumes. Conditional priority resulted in minor delay increases on side streets with high volumes.
The best performing strategy was Conditional FSP Type II and TSP, which limits provision of freight priority only to trucks with FHWA classification of 7 and higher (primarily combination vehicles).
When assessing overall travel time cost, the benefit associated with applying both FSP and TSP on Sunrise Boulevard was found to be approximately 6 percent.

Table: Travel Time Cost for Simulated Corridor

	FSP	TSP	Both FSP & TSP
Travel Time Cost Benefit ($)	6.63%	5.31%	5.97%

The project also provided proposed guidelines for implementation of FSP and TSP, offering a list of factors that should be considered, and supporting decision trees to assess the need for simulation analysis. Factors included:

TSP considerations