The Birmingham Bridge is a generous bridge for the traffic it carries, isn’t it? And why are there these strange wings sticking out at the southern end?

The answer is that the Birmingham Bridge was built in the 1970s as part of a vast network of expressways that would bring Pittsburgh into the automobile age at last, by destroying much of the city and making it easier for suburban drivers to get to major destinations. There was to be an interchange at the southern end of the bridge, with exit and entrance ramps connecting to the bleak expressway-blighted streets below.

Almost all that ever came of the plan was the Birmingham Bridge; the fates had mercy on the city and scuttled the rest of the network. But the stubs of those interchange ramps are still there to remind us how close we came to making Pittsburgh the Los Angeles of the East.