When the urban planning disaster we now call City Hall Plaza was created over three decades ago, it included plans for a pedestrian bridge over Congress Street. The bridge was not built then, but Boston’s urban planners keep trying. A new proposal, pushed by the Trust for City Hall Plaza, is now in the works. It’s a bad idea, and should be stopped.

The proposed bridge would stretch from Faneuil Hall to City Hall Plaza. A suspension bridge, it would have one large upright stanchion south of the Sam Adams statue. The stanchion itself would be nearly the height of Faneuil Hall. A significant portion of the bridge’s $3.0 million cost would be paid for by the state, which sees it as a safety measure.

Indeed, today’s rationale for the bridge is that it will improve pedestrian safety. Right now, tourists, workers and others travel between City Hall Plaza and the North End/Waterfront by walking down the steps to the south of City Hall and using a crosswalk across Congress Street that brings them to Faneuil Hall. In the mid-80s a pedestrian crossing the street was killed by a car. This incident has been the apparent genesis of city planners’ latest burst of enthusiasm for the bridge.

But the pedestrian safety concern makes little sense. After the death in the mid-80s, Congress Street was remade, with fencing put up to control pedestrian crossings. The Transportation Department keeps lists of the most dangerous intersections in Boston. Congress Street is not one of those. Those other intersections could benefit much more from the money to be spent on the crossing.

Indeed, it is questionable whether a bridge itself would really do much to enhance pedestrian safety. Not all pedestrians cross from City Hall Plaza. Those that do not will continue to use the street and the presence of a bridge casting strong shadows may actually increase the risks they face.

There are other objections to the bridge as well. One is obvious. Faneuil Hall is perhaps Boston’s most historic site. It and the sight lines up and down Congress Street would be spoiled by the bridge. There is a sense of mid-60s urban development planning here that is out of keeping with today’s general consensus that Boston should protect its most historic sites.

There is a second important concern as well: street life would be deadened by placing walkers in the air.

Urban planners appear to have a love for airborne walkways. Glass tunnels, called “gerbil runs” by some, take pedestrians from the Prudential Complex to Copley Place. Pedestrian bridges are used to bring people up to the Charles Station red line stop at Charles Circle. In both cases, street life is hurt. Consider, for example, Charles Circle: because of the bridges and unfriendly pedestrian design, few people walk there. As a result the area has, for the most part, been taken over by the homeless.

Pedestrian bridges are admittedly an easy solution to pedestrian crossing concerns. But they are not the only solutions. Better street level design, improved crossing lights, fencing to discourage jaywalking and, yes, a willingness to slow down traffic a bit so pedestrians can walk more easily — all of these are better approaches.

And in the case of Congress Street? For $3.0 million, we could hire a police officer to manage the intersection 16 hours a day, 365 days a year for over 20 years. If that seems a little excessive to you, then, perhaps, so is the bridge.