State transportation officials are moving forward with a project now four decades in the making by adding Light Rail service to the Eastside, Sound Transit announced Wednesday.

"Running trains across a floating bridge is an amazing engineering and planning feat," Sound Transit CEO Peter Rogoff said at a news conference Wednesday. "It hasn't been done anywhere else in the world."

The route will extend 14 miles with 10 stops along the way, executive project director Ron Lewis said. Light Rail passengers will connect to the East Link from the current International District station downtown.

"For thousands and thousands and thousands of additional commuters – tens of thousands in the years to come – Light Rail is going to be an affordable and convenient option and it's going to be an option out of the traffic that you're going to experience on I-90," Rogoff said.

Construction is expected to last more than three years. Work will be limited to specific months throughout the year to limit distress on the bridge.

The center roadway of I-90 is now closed, but Rogoff said drivers won't see construction on the actual roadway for quite a while. A lot of work has to be done to the pontoons under the road.

Commuters won't see the majority of the work in action until around 2019.

Congestion has doubled on I-90 in the last five years, he said. The Light Rail gives commuters an option to get out of the congestion and to guarantee they'll get to work on time.

Twenty-four train and bus projects are planned around the Puget Sound in the coming months and years, Rogoff said. Each project will give people the option to avoid congestion.