Vehicle and Equipment Fleet

The operations and maintenance fleet of the Maryland Department of Transportation State Highway Administration (MDOT SHA) includes approximately 906 light-duty pieces and 1,359 pieces of diesel-powered equipment. A total of 750 of the light duty pieces are gasoline powered.

Maintaining our fleet vehicles at peak operating conditions is one way that we lessen our environmental impact. MDOT SHA also explores innovations and examines best practices to protect the environment.

Some techniques are simple and easy to implement. This includes MDOT SHA’s engine idling policy, which reduces emissions when drivers switch off engines after five minutes of idling.

Other methods involve a little more work. MDOT SHA received a $250,000 grant from the Environmental Protection Agency (EPA) to retrofit many trucks with diesel oxidation catalysts. When installation was complete, we saw a 50% reduction in diesel emissions. Replacement vehicles come with the new filters, so as MDOT SHA replaces aging vehicles, we expect to see even further reductions in diesel emissions.

This effort has enabled MDOT SHA to comply with Clean Air Act standards for ozone and particulate matter levels in the Chesapeake Bay area. To comply with stringent EPA regulations, MDOT SHA purchased dump trucks and heavy-duty on-road vehicles that are now equipped with Selective Catalytic Reduction systems (SCR). When EPA 2010 standards went into effect, no heavy-duty diesel engine could emit levels of nitrogen oxide (NOx) higher than .2 g/bhp-hr (grams per brake horsepower-hour), a standard stricter than that in Europe. SCR is the only technology that meets this standard. In addition, SCR systems reduce NOx emissions by up to 90%, hydrocarbons (HC) and carbon monoxide (CO) emissions by 50-90% and particulate matter (PM) emissions by 30-50%.