East Contra Costa commuters are invited to get on board taking the bus to work.

Tri Delta Transit and 511 Contra Costa are sponsoring a promotion until the end of the year for commuters that pledge to use the bus at least 20 times.

The CommuterPass program, which was introduced last year, provides up to 350 free 20-ride bus passes to commuters who pledge to use the bus as part of their commute, said Mike Furnary, Tri Delta's director of marketing.

"(The service) translates to 350 cars off of our roads and Highway 4, which benefits not only the new bus riders but all of us," Furnary said.

"The way we look at it, the bus does the same thing your car does. However, it costs less and allows you to avoid the frustration of driving in traffic. We're betting that most people would rather read a book, enjoy their smart phone and save some money at the same time."

Tri Delta Transit offers several options to get to BART every weekday, including a limited stop express bus serving Brentwood, Oakley and Antioch.

Tickets are limited and will be awarded on a first-come, first-served basis. There is a limit of one participant per household. Tickets provided are not valid on Dial a Ride.

The deadline to register is Dec. 31.

To get a CommuterPass application, call 925-754-6622 or visit www.trideltatransit.com.

Contact Paul Burgarino at 925-779-7164. Follow him at Twitter.com/paulburgarino.