Whats the average lifespan of a traffic signal before it falls over

[traffic light guy]

In New Jersey, the oldest I've seen are 1950s "8" CH Art Decos and they hold up decently but the truss arm shakes in high winds, In Delaware the oldest are 1970s Span-Wire signals, none of them have fallen down, but the paint has faded, In states like Michigan you see 4-Way clusters and they are in awful shape, but the assembly never falls apart. In PA the oldest are usually 1970s-era mast-arm installs usually with CH Type Rs or Eagle flatbacks and I saw one of that installation and the pole snapped making the whole installation fall to the ground, 40 years is a decent lifespan for a set of traffic signals though.

[M3019C LPS20]

The lifespan of a traffic signal depends on quality, environment, and maintenance. Some municipalities may consider to replace heads once about every ten years, which I think is wasteful if they're still in good shape. Others will keep them in service for years with periodic maintenance considered.

New York City still has a lot of old Marbelite heads that are well over 30 years old, but they're maintained by the city's D.O.T. every couple of years. The poles that support them are still going strong as well.

As I see it, if something ain't broke, don't fix it.

[Mohkfry]

It depends. Who maintains the signals? Where are they located? Does said location update on a regular basis? The oldest signal I've seen maintained by INDOT was a 1970's CH signal. Gary, IN on the other hand, has signals from the 60's that haven't had any upgrades at all. Even today, they are still fully incandescent. The only time something gets replaced in Gary is if it's been knocked down by a car, or if the signal has deteriorated to the point of no return. Auburn, IN has some 1950's CH Art Deco signals in the downtown area, but only because it's part of the historic district. They still have their original smiley lenses as well.

[roadman65]

I guess time is showing proof in the Garden State.  When the oldest assembly finally decays then the answer will be obvious.

Here in Florida we have only a few yellow signal heads that were the norm up until circa 1980.  Since Florida generally replaces installations after so many years, you hardly see any old one's anymore.  The fact that in over 30 years 99 percent of all traffic lights all got the original yellow heads switched out shows that we keep up as much as we can.