Driving back from St. Louis this Christmas, I finally bothered a government agency about something that had been bothering me: road signs.
After Breezewood — a town that makes me want to bring back earmarks so it can be paved over into a normal interchange — there are signs listing the distance to Baltimore, and to Washington. The mileage on one particular sign, as I recall (though I was groggy) varies. Normally it’s a two mile difference, but on another sign, it’s three miles.
So I wrote in:
To Whom it May Concern:
I am writing about the mileage distance signs on I-70 after an eastbound driver departs Breezewood.
I understand that, at some point in the future, the road splits and drivers can choose to head towards a variety of places, including Washington, DC and Baltimore, Maryland.
The first sign says they’re two miles apart, but 20 minutes later, the sign says they’re three/four miles apart. (Not exactly sure here, but point is, the mileage actually varies.)
As a kid, I asked my dad if the two towns were really only X miles apart and he helpfully explained to a 4th grade me that, no, this was the distance on that road system from that particular point, and in fact they were many miles apart.
My question is, why do the PADot signs have varying mileages for them, on the same road, just a few dozen miles apart?
How is this distance calculated? It just seems odd that it would vary on I-70 at one mile marker to another.
Thanks for your attention to my somewhat odd inquiry.
Two days later, the Pennsylvania Department of Transportation wrote back:
Dear Mr. Swift:
I am responding to your email of Monday, December 28, 2015 concerning the Distance Signs on I-70 Eastbound since this matter falls directly under my area of responsibility.
The distance used on these signs is calculated from the location of the sign to the center city of the destination. For a destination that is a considerable distance, there can be some variation in the distance depending on the specific route selected and the specific point selected for the center city. There is no set national procedure for this process. However, I do agree that once the two variables discussed above have been selected, there should be no variation in the difference in the total distance to each destination.
We have reviewed the sign on I-70 immediately east of the Breezewood interchange and the mileage indicated is South Breezewood 2, Washington D C 127 and Baltimore 129. Thus, the difference between the distances to Baltimore and Washington D C is 2 miles and this difference should remain constant. We have further reviewed the four remaining distance signs on I-70 between the first distance sign and the Maryland line, and in fact, found that the difference between the distances to Baltimore and Washington D C remains 2. As an example, the Distance Sign immediately east of the Amaranth interchange has the mileage indicated as Warfordsburg 4, Washington D C 118 and Baltimore 120. The last sign in Pennsylvania has the mileage indicated as Hancock 3, Washington D C 106 and Baltimore 108. Based on the information you have provided, I can only conclude that there are signs you observed in Maryland that have the difference between the distances to Washington D C and Baltimore something other than 2 which may be the result of the Maryland State Highway Administration using different selection criteria than what I have discussed above.
Thank you for taking the time to share your thoughts on our transportation system and the possible conflict in our traffic signs.
Robert J. Pento, P.E. | Manager, Traffic Engineering and Permits
It was a great response! Very satisfying. I wrote back to say thanks, having written a few thousand responses to the public in my short tenure as a government employee, and noted that this was a response from a pro. Now I’ll have to find a Google streetview of that Maryland sign and bother them about the sign, assuming I didn’t misremember or am an undiagnosed dyslexic.
Together we can make change and bring consistency to highway distance signs.
UPDATE: Niels Lesniewski has found the offending sign. It’s just outside of Hagerstown. (And pointed out that there is a webpage dedicated to signs!)