What do these road signs mean?

[DowntownHarrisburg]

Originally Posted by ki0eh

No, on second thought, it really doesn't help the driver much at all.

I laughed at this. Welcome to Pennsylvania!

[ki0eh]

Originally Posted by DowntownHarrisburg

I laughed at this. Welcome to Pennsylvania!

Here's another less reverent dissertation on this subject from closer to a user perspective: Hiker Guide to the Pennsylvania Outdoors

[HappyRider]

I am going to snap pictures of these signs whenever I can and post them here for comparison. Each is formatted differently. So what do those 20s on that sign mean anyway?

[ki0eh]

It means the sign is in segment 20 which is typically the second half-mile segment from that road's point of beginning, except when it isn't.

[Craziaskowboi]

Originally Posted by fisheye

The help we can get, out of these signs, is finding out what route we are on.
This is especially true if you don’t have GPS. The sign in the picture means that you are on state route 662. If you only have a map; that is useful information. The 20’s and arrows have no value to motorist.

I like the mile markers. For a long time we did not have good mile markers. Most states (but not all) count miles from left (west) to right (east) and bottom (south) to top (north). If you are traveling across the state; these can quickly tell you how far you have to go. Furthermore, if you ever have a problem or want to report an accident, the markers give first responders good information.

Pennsylvania has always had mile markers just like any other state. What they didn't have for a period of time was mileage-based exit numbers. For some reason, they switched to sequential numbering during the mid-1970's, and then switched back in the early 2000's. Before PennDOT got serious about replacing old signage, you could see silhouettes of the old exit numbers behind the new numbers on some of the old button-copy signs. Back in the early 1990's, I could tell that Exit 34 on I-79 used to be Exit 130, and I wondered why they changed the exit numbers. (It's back to Exit 130 again). Pennsylvania and Maine are the only states in the Northeast in with mileage-based exit numbers on all Interstates.