Talk:3174: Bridge Clearance

But when the moon is directly overhead they also have to edit the contents of the sign Mathmaster (talk)

The Moon being overhead only applies to places in latitudes roughly between 28.5 degrees N and S, at its absolute most extreme inclinations. So, for the contiiguous US, that potentially affects only roads in some bits of Florida and Texas.

Louisiana's most southern point is very close to that, such that the 'upper limb' of our satellite would 'overhead' an additional quarter of a degree of latitude, taking in this spot and a bit more. But that location is also an island. Port Fourchon, Louisiana, seems to be the most southerly stretch of regular (mainland) road in that state, and that's still just too far north to be affected. 78.144.255.82 23:10, 28 November 2025 (UTC)

Note how the second sign extends off the panel, presumably with a warning further up for any vehicles under clearance. That’s quite the space elevator. KelOfTheStars! (talk) 01:21, 29 November 2025 (UTC)

Also note that in latitudes where the moon could possibly be directly overhead, the sun could also be directly overhead. This would also necessitate a change to the sign 24.210.252.188 02:56, 29 November 2025 (UTC)

When I first read the title text I thought it was talking about the tide's effect on the height of the bridge. Barmar (talk) 03:55, 29 November 2025 (UTC)

How old is the sign that needs to he updated every day? These days they have automated signs for things like travel time to important exits, that type of system could easily be used to keep the clearance up-to-date. Barmar (talk) 03:59, 29 November 2025 (UTC)

> clearance of 10 feet and 6 inches, which is a realistic clearance Anything less than 13'6" (in the US) will get hit frequently. Yes, we know some bridges that get hit frequently. --PRR (talk) 06:42, 29 November 2025 (UTC)