Read something online recently about roads that have a different speed limit for each direction of the road. Not from construction or there being more/less lanes, but just a different limit for each side. What are some examples of this and what is the reasoning?
I-94 in Dearborn. 70 MPH WB/55 MPH EB the reason, the Ford Freeway was built to a 55 MPH standard starting in the late 40s, whereas the WB section is interstate standard for 70 MPH.
I don't know whether it's still the case, but in the summer of 1997, I-65 just north of the Alabama River near Montgomery had a 70-mph speed limit northbound and a 60-mph speed limit southbound for traffic approaching the city. I guess I could look at Street View, but I'm not motivated to do so.
I don't know whether this one counts: On I-95 in Virginia, the reversible HO/T center carriageway generally has a higher speed limit than the general-purpose lanes to either side of it (for the most part, it's posted at 65 mph while the general-purpose lanes are posted at 55 or 60, and there's a segment further south where the HO/T lanes are posted at 70 while the general-purpose lanes are posted at 65).
There are multiple instances of 55 mph zones on I-79 south of Washington, PA on only one side, the other side was still 70
These examples are actively being reviewed for a change to get the discrepancy fixed.
SR-20 east of Hawthorne has a short section signed 45 EB (https://maps.app.goo.gl/LkPCGe2V6szrNFBd6) and 50 WB (first 50 sign: https://maps.app.goo.gl/jvLYHvYLHpDLagwP7 || where the EB 45 zone effectively ends: https://maps.app.goo.gl/ZigHmzPnZhp1ae6k7).
Much of SR-230 is signed as 60 WB and 55 EB, though it technically is only 55 in Bradford county. EB 55 sign: https://maps.app.goo.gl/ahPV8oBY2QZWJDWW7 || EB 60 sign: https://maps.app.goo.gl/86uKvvTkCuUAVMZAA || WB 60 sign: https://maps.app.goo.gl/K24MCWyzVnCbqos46
Frontier Parkway on the Prosper-Celina line in North Texas is signed 45 mph eastbound but drops to 30 mph westbound starting a quarter-mile back of the traffic signal at Preston Road. I'm guessing reason being because of backups at the signal.
There was a time where I used to live where a 2-lane county road was 35 MPH SB and 45 MPH NB... The former was technically within the city limits, while the latter was in the adjoining township.
NY 27 in western Nassau, near the Queens border has two different speed limits. Westbound is 45 mph and eastbound is 40. This is because the westbound lanes run parallel to the LIRR tracks, so there are few parking lots/driveways on that side. The eastbound side has many parking lots and intersections.