DART’s success led the transit agency to purchase a total of 165 propane autogas shuttles — over one-half of the entire paratransit fleet. DART

DART’s success led the transit agency to purchase a total of 165 propane autogas shuttles — over one-half of the entire paratransit fleet.


Delaware Transit Corp. provides over 10.6 million rides per year, including about one million passenger trips through its DART paratransit service. The transit agency runs a shared-ride program with advanced reservation trips for people with disabilities, who are unable to use regular fixed-route public transportation.

The agency, which operates the largest self-managed paratransit fleet in the nation, took on a two-year pilot program testing five propane autogas paratransit buses in 2014. The agency chose to pilot two different types of vehicles, dedicated (only operating on propane) and dual-fuel (operating on gasoline or propane).

The program’s success led the transit agency to purchase a total of 165 propane autogas shuttles — over one-half of the entire DART paratransit fleet. Each of these vehicles is built on the Ford E-450 chassis with 6.8L V10 engine, and equipped with a ROUSH CleanTech-dedicated propane autogas fuel system. ROUSH CleanTech has deployed more than 18,000 fleet vehicles fueled by propane autogas, including about 1,200 in the transit industry.

This propane vehicle has completed Federal Transit Administration’s New Model Bus Testing Program (Altoona Testing) and is certified for sale in all 50 states by the California Air Resources Board and Environmental Protection Agency.

“Our first five propane-fueled buses collectively traveled 450,000 miles with no fuel system-related failures, and saved $15,000 in fuel costs alone,” said John T. Sisson, CEO of Delaware Transit Corp. “That, combined with the reduction in greenhouse gas emissions, made it an easy decision to expand the propane program with our new private fuel stations and expansion of the propane fleet.”

Environmental Savings
Kept in operation for five years, each DART paratransit bus travels between 35,000 and 40,000 miles annually. Every paratransit bus consumes about 7,275 gallons of propane autogas, annually, saving about 6,250 gallons of gasoline. More than 90% of the U.S. propane autogas supply is produced domestically, with an additional 7% from Canada.

The propane autogas paratransit buses are each emitting 91,000 fewer pounds of carbon-dioxide emissions over its lifetime, compared to the agency’s gasoline models — or 15 million pounds for the entire propane fleet. Propane autogas is a low-carbon fuel that reduces greenhouse gases by up to 25%, with 60% less carbon monoxide and fewer particulate emissions, compared with gasoline.

Cost Savings
To track costs, the transit agency runs a weekly report based on the number of vehicles in service, their total mileage, and gallons of propane autogas used. Based on the current price of propane autogas and gasoline, the agency then calculates its weekly savings.

In March 2018, savings averaged $76 per bus per week. The Delaware Transit Corp. is saving about $11,000 per week by operating a propane autogas paratransit bus fleet, equaling more than $500,000 annually in fuel expenses alone. The agency has calculated a 36% cost-per-mile fuel savings, with 19 cents for its propane shuttles, compared with 30 cents for its gasoline shuttles. Historically, propane autogas costs 40% less than gasoline and up to 50% less than diesel.

DART also has experienced maintenance savings due to the fuel’s clean-burning properties. “We’ve seen a significant reduction in engine-related problems. Overall performance of the vehicles is greater, and we have experienced far fewer engine-related breakdowns,” said Richard Walters, DART’s fleet and contract operations director.

Essential to daily operations, the transit agency installed private fueling infrastructure. DART worked with Sharp Energy, a local propane provider, to install two low-cost refill stations at different, convenient locations. Propane autogas fueling infrastructure costs less than any other transportation energy source — conventional or alternative. Sharp Energy provides the propane for the DART paratransit buses, along with technical and maintenance support for the vehicles and fueling stations.

Best Practices in Action
According to Walters, the agency drivers have found the switch to propane to be an “easy one, and have commented that the only difference is propane autogas has better acceleration and more power than gasoline or diesel.”

DART tested both dual-fuel and dedicated propane autogas vehicles before making the decision to purchase only dedicated vehicles. “We found the dedicated system far superior to the dual-fuel system,” said Walters, who recommends that other transit agencies learn from their experience.

Delaware Transit Corp. is realizing the economic and environmental savings that comes with adopting propane autogas. And, the agency expects that momentum to continue as it plans to convert its entire paratransit fleet to propane autogas by 2020.  

Todd Mouw is president of ROUSH CleanTech.