Bloomberg reports that United Parcel Service (UPS) will expand its fleet of natural-gas trucks by purchasing 285 natural-gas powered vehicles next year.

The purchases will build on a previously announced buy of 700 natural-gas trucks, David Abney, the Atlanta-based company’s chief operating officer, said in an interview. UPS sees liquefied and compressed natural gas as a “bridge fuel” over the next decade, he said.

In addition, UPS announced that the company is building nine additional natural-gas filling stations, Abney said. Three will be in Tennessee, which has a favorable regulatory environment and a year-round supply of natural gas available for transportation.

The company’s alternative-fuel trucks have logged 300 million miles since 2001 with a goal of reaching 1 billion by 2017. Through better information, route planning and telematics, UPS trucks drove 364 million fewer miles between 2001 and 2012, Abney said.

UPS fleets travel about 2.9 billion miles a year, company spokeswoman Kara Gerhardt Ross said.