Nick from Denver writes, “What’s driving you crazy? Going north on I-25 from the Denver Tech Center, there’s a sign on the left that indicates the exit for Hampden Ave is 3/4 of a mile. Then, approximately 1/4 to 1/2 of a mile later, there’s a sign that indicates the Hampden Avenue exit is in 1 mile. I get they are estimates, but what gives?”
We all rely on these mile signs to get where we want to go, and we all assume they are pretty close to the right distance. You are right Nick, these distances are not precise to the nearest foot. In general, these signs show distances measured to the nearest 1/4 mile from the sign to the gore point at the exit. The gore point is that triangular area of unused road between the main interstate lanes and the exit lane.
I brought your question to CDOT and Ben Kiene, Region 1 Traffic Operations Engineer, tells me they think a 1 has gone missing.
“It looks like the viewer is correct regarding the error on the median sequence sign, which should be 1 3/4. Yale and Evans are closer to 2 1/2 and 3 1/2 respectively as well. I think we replicated the TREX plans when we replaced the panels here though the 1 seems to have gone missing. We'll correct this with masking stickers.”
According to CDOT, distance signs to a city or place are usually measured roughly along the most common route to the center of the city or town, which can include other roads. For example, the center of Fort Collins is about four miles west of I-25 so distance signs on I-25 generally reflect that despite Fort Collins having annexed land all the way to I-25 itself in recent decades.
Your question made me think about the accuracy of mile markers on the interstates. The Federal Highway Administration Manual on Uniform Traffic Control Devices states, “If a reference location sign cannot be installed in the correct location, it may be moved in either direction as much as 50 feet. If a reference location sign cannot be placed within 50 feet of the correct location, it should be omitted.”
By the way, numbering of the markers begins at the state line in the south for north-south routes and in the west for east-west routes. That means mile marker 1 on I-25 in Colorado starts just after the New Mexico state line and mile marker 1 on I-70 is just east of the state line with Utah.
Denver7 traffic anchor Jayson Luber says he has been covering Denver-metro traffic since Ben-Hur was driving a chariot. (We believe the actual number is over 25 years.) He's obsessed with letting viewers know what's happening on their drive and the best way to avoid the problems that spring up. Follow him on Facebook, Twitter or Instagram or listen to his Driving You Crazy podcast on iTunes , Stitcher , Google Play or Podbean.