The District Department of Transportation hopes to open the second span of the new 11th Street Bridge this weekend. That will launch a year of dramatic changes for the many thousands of travelers who cross the Anacostia River.

At about $300 million, the new bridge should provide some serious bang for the buck.

It’s not a straight-up replacement of an old thing with a new thing. By the time work is all done in the middle of next year, it will have separated through traffic and local traffic, providing seamless highway connections for the through traffic and convenient access to neighborhoods for the local traffic.

But even after the second span opens this weekend, most of that goodness will still be ahead of us. The project, which began in December 2009, has progressed a bit like the Wilson Bridge or the Beltway HOT lanes project. First, they build a new part along side the old part, then open a new part and shut the old part to make room for another new part.

The first big piece to open last year was the new flyover ramp for I-295 southbound. Then in mid-December, the first of the new spans opened. Because it was so close to the holidays, drivers still are getting used to this. It created a new configuration for drivers coming north on I-295 who must pick lanes to either continue north or take the bridge span heading toward downtown D.C.

The new outbound span, scheduled to open Saturday, will require drivers heading to neighborhoods just east of the river to take some different routes. I’ll write more about that on Sunday’s Commuter page in The Post.

With the two new through spans open, crews will work on completing the ramps to connect the Southeast-Southwest Freeway and the Anacostia Freeway (295) via the bridge.

One major closing is coming up in March to further advance the construction. DDOT will permanently close the 13th Street ramp to the inbound bridge. That will require local traffic to detour and will create some delays.

The real benefits of the project will start to appear in spring and summer as new ramps are completed. Also in the summer, the third span is scheduled to open.