Dating a Bridge

[kphoger]

Don't talk about your unit.

As discussed in the Metrication thread, smaller units can be more useful.

[Max Rockatansky]

Don't talk about your unit.

As discussed in the Metrication thread, smaller units can be more useful.

It's not the size of the unit that counts, it's how you use it.

[kphoger]

It's not the size of the unit that counts, it's how you use it.

Wait, are we talking about something other than decimals now?

[jeffandnicole]

It's not the size of the unit that counts, it's how you use it.

Wait, are we talking about something other than decimals now?

The Arch.

[freebrickproductions]

South Carolina has also done this consistently with their bridge parapets since at least the 1930's, and I've noticed this a few times in Alabama as well but it's not consistent.  If you travel the circa mid-80's constructed section of I-65 north of Birmingham, specifically around Kimberly and Morris, the bridge parapets will have one year on the right side (either 1986 or 1987) and a different year on the left side when it was widened to six lanes (can't remember if it was late 90's or early 00's).

Getting slightly back on (the intended) topic, I think ALDOT started casting the dates into the railings of their bridges in the 1970s, when they switched to Jersey-style barriers, as the earliest I've seen a year was from sometime in the 70s in the rural parts of eastern Colbert County, I'd have to go find it again.
The older bridges (with the older styles of railings) don't seem to have typically featured the years on them. Some old railroad overpasses did, however.

EDIT: Here's the bridge I was thinking about. You can see the 1979 year cast onto the railing.

[Tom958]

What are some giveaway characteristics that you can spot on a bridge and tell automatically when it was built?

I'm not well-traveled enough to say it definitively, but I think Georgia's one of the easiest states for what you're talking about, at least in the pre-Jersey barrier era. Distinctive guardrails are the main reason-- there's the move away from concrete stringers to steel, but that's a redundant factor.

[Road Hog]

Arkansas typically puts mini-plaques on the railing heads of bridges. I've seen them stamped into the Jersey rail of Louisiana bridges. But Texas is hit or miss.

[chrisg69911]

NJ has been doing it since the 30s. They also used to imprint the highway number on the opposite side, which now means a much of bridges have mismatched numbers. https://maps.app.goo.gl/QMMx24nPCRVZet4D8

Bridges built in the 60s and 70s I'm pretty sure used poor quality concrete for the dates so now wherever the date is supposed to be there's just a hole. Can't find any now on gsv but they exist.

Now they imprint the date into jersey barrier.
https://maps.app.goo.gl/q2SBBSxC8VnGkc9y6

I've actually seen them put future years on bridges, like 2024 on a bridge in 2023