Monument Valley

[agentsteel53]

I don't recall California having nearly as bad a sign-fading problem.  sure, we have lots of faded signs, but that is because ours are positively ancient: 30-40-50 years old.  Arizona is very, very aggressive with its sign replacements: the oldest sign I know of surviving in the state is a 1985, an I-40 trailblazer on a side street in Winslow, likely forgotten by the DOT.

[andy3175]

I don't recall California having nearly as bad a sign-fading problem.  sure, we have lots of faded signs, but that is because ours are positively ancient: 30-40-50 years old.  Arizona is very, very aggressive with its sign replacements: the oldest sign I know of surviving in the state is a 1985, an I-40 trailblazer on a side street in Winslow, likely forgotten by the DOT.

I think that's because California didn't use reflective signage as the primary guide sign standard until 1999 (the first such signs I saw were along California SR 94 when they added the ML King Fwy designation). The older signs are non-reflective/button copy, and for whatever reason, color fading did not happen as readily with those, especially porcelain enamel signs (although those colors do not come through as readily at night). But the newer, reflective signs do show some fading, especially on I-5 southbound/northbound overhead guide signs between La Jolla and I-8 (especially the red color on the interstate shields on the I-8 junction and I-5 pull through signs). Several roadside Interstate shields show the red part of the I-5 and I-8 shields fading to pink. Another example is in El Centro: the city-maintained Imperial Ave Business Loop I-8 signs have seen significant fading (some almost to white), very comparable to what was seen above in the Loop 202 signs in Phoenix. Having said that, Caltrans usually does well with reassurance route marker shield replacements.

Regards,
Andy

[agentsteel53]

yes, the examples I was thinking of are route markers, which are green and white - I just don't know of very many examples of, say, CA-86, 111, 115, other desert numbers, which are as badly faded as some of those 202s. 

I know of lots of route shields, as well as various experimental retroreflective guide signs, which are badly faded and they are from the 70s and 80s - not 2001 like the Arizona signs.

[J N Winkler]

I don't claim any particular expertise in terms of sign sheeting life or performance, but I believe there are two factors at work in southern Arizona which may not be present to nearly the same degree in other places at similar latitude with similar climates.  First, temperatures are generally much higher--the Phoenix area has daytime highs above 100° F for almost six months of the year.  Second, UV light flux may be both higher in absolute terms and more continuous throughout the day.  These factors probably work in combination to accelerate the aging of sign sheeting beyond what you would expect in places which have high UV but comparatively lower temperatures (such as upland Colorado) or high temperatures but low UV (such as Texas).

Edit:  Link to solar power resource map (solar power is one possible proxy for the factors that accelerate aging of retroreflective sheeting).

[swbrotha100]

I did a little road trip to northern AZ last week. The most faded signs I've ever seen (that are surprisingly still standing) are the I-17 NB signs for Montezuma Castle National Monument (Exit 289). They were brown at one point, and now they look more like a faded green. Almost no clue those signs were ever brown.

Via the Cross Country Roads website, here's a picture of what the sign looked like back in 2004:

http://www.crosscountryroads.com/Images/AZ%20I%2017%20N/i17azexit289.JPG