A Return on Investment (ROI) study of the SSP in Hampton Roads, Virginia estimated the benefits attributable to the SSP from reductions in motorist delay, fuel consumption and emissions by analyzing traffic and incident data from July 1, 2005, through June 30, 2006 (1 year).

METHODOLOGY

The study compared the “begin” and “end” times of incidents on SSP routes to those on non-SSP routes (Virginia State Police (VSP) assist only). The study also used the Freeway Service Patrol Evaluation (FSPE) model to estimate incident-induced delay and associated delay savings attributable to SSP operations. The FSPE model employs deterministic queuing models to estimate motorist delay associated with queues that form during incident conditions. (Note that the results of the FSPE model did not account for day-to-day or seasonal variations. The study also did not attempt to estimate reductions in secondary incidents, or environmental or medical costs associated with SSP operations.)

Model parameters included:

• Freeway capacity values and remaining freeway capacity factors due to incidents from the Highway Capacity Manual 2000
• Emission rates from the Hampton Roads Planning District Commission (HRPDC)
• Clearance time reduction data from an analysis of the VSP CAD and Virginia's Archived Data Management System (ADMS) databases
• Travel time costs and fuel costs from the Texas Transportation Institute (TTI)
• Occupancy rates (persons/vehicle) from the Federal Highway Administration’s (FHWA) 2001 National Household Travel Survey

FINDINGS

• The estimated total delay and fuel benefits per year were $11,075,893.
• The estimated savings in motorist delay per year were $455,856.
• The estimated fuel consumption savings per year were $687,624.
• The estimated emissions savings per year were 118,131 kg for reactive organic gases, 805 kg for carbon monoxide, and 12,115 kg for nitrogen oxides.

The table below shows the estimated annual savings in delay, fuel consumption, and emissions for different Hampton Roads SSP routes.

Route	Annual Delay Savings (vehicle-hour)	Annual Fuel Consumption Savings (gal)	Annual Emissions Savings
			Reactive Organic Gases (kg)	Carbon Monoxide (kg)	Nitrogen Oxides (kg)
Naval Base/Reversible Roadway (I-64 and I-564)	138,843	209,434	5,521	246	3,690
Hampton Roads Bridge Tunnel	59,620	89,932	2,372	105	1,585
Coliseum A/Coliseum B	20,149	30,393	802	35	536
Highrise	21,683	32,707	863	38	576
Downtown Tunnel	21,434	32,331	852	38	569
Monitor-Merrimack Memorial Bridge Tunnel	10,669	16,097	424	18	284
2 Outer/2 Inner (I-264)	183,458	272,733	7,297	325	4,875
Total	455,856	687,624	18,131	805	12,115