When the A-line rapid-bus service debuted two summers ago, transit planners called it a “historic” addition to the Twin Cities’ public transportation network. Since then, the A-line has proved to be a star performer for Metro Transit, with ridership along the route increasing by more than a third in its first year alone.

In the coming years, 10 more rapid-bus lines will snake throughout the metro’s busiest transit corridors — and last week, the network’s build-out reached two milestones. Advocates say rapid-bus service offers passengers a light-rail-like experience but is far cheaper to build and maintain.

On Wednesday, the Metropolitan Council approved a $13 million contract with Thomas and Sons Construction of Rogers to build the C-line, the Twin Cities’ third rapid-bus line, which will run from downtown Minneapolis to the Brooklyn Center Transit Station, largely along Penn Avenue. The $37 million C-line is expected to begin passenger service next year.

And Metro Transit is seeking feedback on station plans for the D-line along the Route 5 corridor, which has the highest bus ridership in the Twin Cities, running from Brooklyn Park to the Mall of America.

Rapid-bus service is generally faster than traditional buses. A 2012 study found that regular buses in the Twin Cities were moving just 42 percent of the time they’re in service; otherwise, they’re boarding customers, sitting at red lights or stuck in traffic.