I was surprised that nobody mentioned this yet, as I first found out about the closure via a VMS in Western Colorado this afternoon -- Over 400 miles from the incident.
Recent heavy monsoonal rains & subsequent flooding took out a significant stretch of I-15 between Mesquite (NV/AZ Border) and Las Vegas. Forcing a major detour for large vehicles and a sizable detour for cars.
Story: http://www.8newsnow.com/story/26501983/temporary-fix-for-washed-out-i-15-could-be-ready-by-friday
Detours: http://www.8newsnow.com/story/26489984/parks-offer-detours-around-washed-out-i-15
NDOT is hoping to create a temporary fix for I-15 traffic by this weekend as per the story.
Meanwhile, back in Western Colorado along I-70, this is what the VMS sign states about the closure:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.cotrip.org%2Fimages%2Fdms%3FimageURL%3D62374342%26amp%3BfileName%3DDMS_6595_2014_09_11_09_15_18_0_327x87.gif&hash=1fdc06d36b024b57587bae0934842e6973206d46)
I-80 !?!?!??
It would be the only freeway alternative heading west.
Nevada needs to call PCI, they'll fix it right up !!!
But either CDOT or whomever is giving CDOT information is implying that there is no other way to Vegas and points south, even though there is a detour for large vehicles beginning in Cedar City, UT.
Plus from the CO/UT border, the quickest way to I-80 is via either US-50 or US-6 to I-15 to Salt Lake City. And I don't know of a single, sane person who would take an all-interstate detour to L.A. via Sacramento/I-5 just because I-15 has a closure in Nevada. You are better off taking US-191 south through Moab, US-160 to Flagstaff then I-40 west to Barstow if you want a creative, yet sensible detour from Western Colorado.
The sign operator has another issue... "I-15 in Utah closed at Mesquite"
Mesquite is in Nevada, right near the Arizona state line. They should have said "I-15 South closed at Mesquite NV."
They should also state something like "Detour to Las Vegas use (route)", as drivers may not know where Mesquite is in relation to the closure.
Further discussion in this Pacific Southwest thread: https://www.aaroads.com/forum/index.php?topic=13436.0