East Japan Railway Co. said it will start laying the groundwork Thursday for wholesale renovations of Shibuya Station in Tokyo that will take more than a decade to complete.

In the end, there will be a new 46-story building with offices and shopping malls, a single platform for Yamanote Line trains heading in opposite directions and easier access to the Saikyo Line, according to JR East.

Four different railway operators use Shibuya Station, one of the busiest stations in the nation’s capital. But “the structure of the station is complex and aging, so it is not really easy to figure out where to go when people transfer,” said Yoichi Suzuki, a JR East spokesman.

Now 350 meters away, after renovations the Saikyo Line platform will be next to a single Yamanote Line platform, vastly shortening transfer times.

Passengers now have to be careful to choose which of the two Yamanote Line platforms they need, depending on where they’re going. One heads for Shinjuku, the other for Shinagawa. Eventually both trains will leave from the same platform.

But it’s anybody’s guess when this will happen. JR East says it doesn’t yet know how long the renovations will take to complete.

Not all changes will be on the inside. Three new buildings are planned outside the station.

A 46-story building will grace the east side by 2020. On the west side, there will be a 13-story building by 2027 and a 10-story building between them.

For now JR East said it’s preparing for the work by securing construction space and repairing the entrance to the Saikyo Line.

The carrier said it aims to begin full-scale construction in fiscal 2015.