Seattle’s King County Metro Transit (Metro) will replace its aging trolley fleet with new all-electric New Flyer coaches that will take about one-third less energy to power. Metro is second only to San Francisco in having the largest electric trolley fleet in the nation.

Metro plans to initially purchase up to 141 trolley buses — about 10% of its entire fleet — under a contract with New Flyer totaling up to $164 million. Future bus purchases will be dependent on fleet needs and whether Metro is able to avoid service reductions in the coming years.

“Electric trolleys have a lot of fans, and I’m one of them,” said King County Executive Dow Constantine. “They’re quiet, they run clean, they’re part of our transit heritage, and studies confirm they’re the best for moving riders in our very hilly and dense urban environment.”

Federal and Metro capital funds will be used to purchase the buses, with the first prototype expected to arrive in 2014. Riders can expect to see new coaches hit the streets in 2015.

The contract will also be a cost-saver for the county. Metro has teamed up with the San Francisco Municipal Transportation Authority (SFMTA) to purchase replacement coaches from the same contract — a move that ensures both Metro and SFMTA get the most competitive pricing.

In recent years, Metro has refurbished older buses in order to extend their service life. But the electrical systems and motors on these aging coaches have become outdated and unreliable.

A 2009 county performance audit confirmed that, compared to their diesel-hybrid counterparts, electric trolley buses are quieter, use less energy, are better on hills and are more cost effective to operate.

The trolley buses being replaced include 60-foot Breda buses originally purchased in 1990 to operate as diesel-electric and later converted to electric-only buses. Metro also is replacing its 40-foot Gillig buses that have antiquated 1979 propulsion systems. Based on age and operating costs per mile, they are less reliable and more expensive buses to maintain.