The Triangle Transit Authority rolled out a spring makeover Monday, with a handful of low-floor buses wrapped in new colors and tagged with a shortened name for the three-county agency: Triangle Transit.

Five new 35-foot-long buses made in California by Gillig Corp. joined the Triangle Transit fleet this week, with 18 more expected to be on the road by the end of June. The buses are decorated in Triangle Transit's new logo of blue, orange and green triangles.

The 23 new buses will replace aging shuttle vans and Thomas buses, made in North Carolina, that have been plagued with maintenance problems. An eight-year-old Triangle Transit bus caught fire last week as it was pulling into a park-and-ride lot in Chapel Hill.

Raleigh's Capital Area Transit has added 15 40-foot Gillig buses to its fleet in the past month. CAT expects to receive three diesel-electric hybrid Gillig models by January.

The Gillig buses burn ultra-low-sulfur diesel, with 3 percent of the sooty sulfur that was in diesel fuel before last year, when the nation switched to the cleaner formula. These buses can also run on biodiesel.

Triangle Transit follows CAT and Chapel Hill Transit in shifting to a shorter name that emphasizes its function rather than an agency moniker. Its proper legal name is unchanged and still a tongue twister: Research Triangle Regional Public Transportation Authority.