FST Chooses Bi-Fuel over Dedicated CNG Buses

FST Chooses Bi-Fuel over Dedicated CNG Buses

Over the years, the Fort Smith, Ark., Transit Department (FST) has had some issues with its dedicated compressed natural gas (CNG) bus. Nonetheless, the department recently pushed ahead and bought two more CNG-powered buses. This time, though, the FST opted for bi-fuel vehicles.


The FST operates about 15 cutaway buses and converted a Ford E-450 to run solely on CNG in 2012. Although the CNG vehicle helped save on fuel costs, FST Director Ken Savage tells NGT News the department soon discovered operational challenges with the bus.

According to Savage, one of the main problems was that the bus did not have enough tank storage capacity to participate in a regular fixed route without having to disrupt operations and refuel while in service.

Making things worse, he says, it was sometimes difficult for drivers to gauge exactly when the bus would run out of CNG. In fact, the department had to tow the vehicle in several instances when the bus accidentally ran out of fuel, and workers became reluctant to take it on the road.

Other issues the FST encountered included minor problems with the bus’s fuel injector, fuel pressure regulators and leaky lines – not necessarily issues that can be attributed to dedicated vs. bi-fuel NGVs, but issues that are vexing for a fleet, nonetheless.

Ultimately, the department decided to operate the bus on a shorter route and use it about half as often as its other buses. Savage is happy to report that the CNG vehicle just had its best year of performance thus far in 2014.

“Game changer”

Savage confesses that the department’s experience with its first alternative fuel bus “left a bitter taste in our mouth about CNG.” However, the FST recognized that CNG still represented a cheaper, more environmentally friendly fuel option compared to gasoline.

“That was enough to try and work something out,” he says.

The department recently bought two new bi-fuel buses, which automatically switch to gasoline once the CNG is exhausted. Local vendor Falcon CNG performed a custom conversion on the two Ford E-350 cutaways.

Savage calls the bi-fuel systems a game changer, as they provide more flexibility for the department to avoid interrupting service and guarantee the buses won’t run out of fuel while on a route. As he says in a recent FST announcement, “This system makes CNG a good fit for us.”

Each conversion had a price tag of about $25,000, and the FST used a grant from the Federal Transit Administration to cover 90% of the costs. Without the grant, Savage says adopting a CNG program for his fleet would be tough.

The FST expects a return on investment on the federal grant to take about three years, but the department should recoup its 10% portion of the cost within about 3.5 months.

The FST has performed early testing on the new bi-fuel buses, and Savage says the vehicles are working “flawlessly.” They are currently being prepared to enter regular service and operate on fixed routes soon. As with the dedicated CNG bus, the bi-fuel vehicles will refuel at any of three CNG stations in the Fort Smith area.

In addition, the department expects to take delivery of two new vehicles this year, and the FST says those, too, are slated to be converted with bi-fuel systems.

“We will continue to monitor the data, fuel markets, and maintenance costs with an eye toward transitioning our entire fleet to CNG as existing vehicles meet their useful life,” Savage says in the FST announcement.


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