Appropiate Roads

Pennsylvania invests too much in shiny new bridges while letting their existing infrastructure rot 🌉 🐷

I am as surprised as any one about the Forbes Avenue bridge collapse in Pittsburgh, especially because it’s a fairly generic, not that old, non-fracture critical, boring old batter-post rigid box bridge. Usually bridges that collapse these days are more exotic types, with multiple high risk joints, that without careful maintenance could fail. But this was a very generic bridge, a design well-repeated and used all over after the Silver Bridge Disaster in 1967 encouraged engineers to re-think how they built bridges.

The Forbes Avenue bridge was in poor condition but was not believed to pose a safety hazard, as it was still open to the motoring public when it collapsed. It was if anything thought to be an exceptionally safe, if not boring design — it’s radical simplicity gave it all of elegance when it first opened, earning awards of the architectural press. Honestly, I think batter-frame rigid boxes are ugly, part of the radical honesty of the late 1960s and 1970s that were part of the general theme of the Brutalist movement of architecture. The old-style truss bridges, disfavored after Silver Bridge, often are a more aesthetically pleasing then the ever-so generic girders propped up by the batter-posts.

Probably the bridge inspectors for the Forbes Avenue bridge had to yawn when they came to inspecting this ever so generic, and generally-believed to be very safe bridge design. There just isn’t a lot of history of rigid box bridges falling down. The bridge was getting to it’s mid-life and was due for an overhaul, a victim of decades of deicing chemicals and heavy traffic. It was rusty, but so are most bridges in an area where there are so much salt used everywhere. But traditional engineering practice suggests such a bridge shouldn’t fall down — as they have a lot of redundancy and safety built in. Clearly though, engineers hadn’t factored in how bad deterioration of the bridge was from deicing chemicals — COR-TEN weathering steel tends to hide the rust and the NYS DOT did a study not that long ago saying that deicing chemicals with water pooling up on a weathering steel can be very bad news.

Whether or not painted steel is more durable then the modern weathering steels developed in the 1960s is debatable, rust really shows up on traditional steel painted bridges. Who knows — weathering steel has proven to be the bane of NYS DOT in recent years for thinner applications like guard rails, and never stopped weathering on COR-TEN US Steel Building in Pittsburgh, leading not only to rust stains but holes in the outer frame of the building, which they ultimately tried to arrest by sealing the weathering steel in recent years. Several COR-TEN buildings in particularly salty locations, like the Nassau Coliseum ultimately were demolished due to salt deterioration, preventing the steel from ever self-sealing itself and continuing to rust away dangerously.

But ultimately, the problem is Pennsylvania like so many states has politicians more interested in shiny new superhighways and bridges, rather then repairing existing bridges. It cost money to repair existing bridges, and sometimes those repairs aren’t cheap. But often repairing a bridge is a lot cheaper then tearing down and throwing away the existing bridge, and building a new one. Sometimes the fix is especially cheap — like pressure washing the underside of the bridge annually to remove accumulated dirt and deicing chemicals. A 50-year old bridge shouldn’t collapse or need replacing except in exceptional cases like when there was an engineering mistake that lead to premature failure. Yet, any bridge needs some maintenance, you can’t just build a bridge and forget about it for half a century. Necessary repairs shouldn’t be deferred forever, even on what is considered to be a safe bridge design with low risk of failure. Even the best and safest bridge which is not maintain can fail.

Now the politicians will claim the United States doesn’t spend enough money on infrastructure. But Pennsylvania has one of the best Departments of Transportation in the nation, with the highest gas tax and tolls on highways. And they are proposing to toll even more bridges. They are celebrating the infrastructure bill and the billions it promises the state, but I have wonder if that money won’t be squandered on show-case new superhighways and extensions, rather repairing existing infrastructure. Even if a lot of the money is dedicated for fixing existing infrastructure, will it not mean that state politicians won’t decide to take money from bridge maintenance accounts, to fund other projects, now they are getting a ton of “free government pork” from Washington DC?