Do 2 lane roads in dense urban areas, complete with cars parking and making turns, really outperform single-lane travel roads with appropriate turn lanes?
Probably not, but with a giant
pile of asterisks about the word "appropriate".
- If the turn lanes aren't sized appropriately, a turning queue backup now stops all thru-traffic.
- Away from the intersections, if there isn't a constant center turn lane + there's anything at all to make a left turn into - same deal - one guy wanting to make a left into his driveway now stops all thru-traffic.
- When there aren't cars waiting to turn (or where we're currently talking 2 lanes each way + left turn lane) at the intersection - it does get more queued up cars through a light cycle. You may not need 2 lanes away from the intersection queues, but at them it does move more cars - even if they just compress back down to 1 lane a couple hundred feet on either side of the intersection.
- You mention parking cars and that's another obstacle - if you've got 2 lanes or at least a center turn lane you just go around the guy trying to parallel park.
- The extreme abuse of double-parking in the city and lack of enforcement means lots of roads wind up with outright roadblocks in a lane for 5-15min at a time, if it's a single-lane road that requires going around into oncoming traffic. This is especially bad in "downtown" areas with Uber Eats + entitled idiots.
To be clear I'm not making a value statement about if a road diet is bad here, especially since I don't go to this part of the city much. As general opinion I don't think going from 2|2 to 1|turn|1 cuts capacity much, but going to 1|1 does in a lot of places.