3 ms·

Better yet, replace intersections with roundabouts. But that would mean knocking down a lot of buildings.

zamadatix 5y ago
Roundabouts are fantastic for the low to mid traffic density case. When you get into proper city traffic density it can start to become very problematic, particularly if you don't have a good solution for pedestrians or cyclists to bypass each roundabout crossing. Even with that roundabouts tend to get a bit chaotic once they reach the point of "is expected to have a constant stream of cars in it for the next 2 hours" which can get particularly troublesome if the traffic in each direction is unbalanced and you get people awkwardly changing up yielding rules to let the one person going east-west in or that person tries to floor it to make it in an iffy gap. Also if you're relying on them as the only means of left turn (via u-turn) the wait times can significantly increase on busy roundabouts. That being said I absolutely love roundabouts in low/mid density areas. They finally converted the street I live on from 4 "pack cars into wait groups" stoplights and 1 "the highway just turned into an avenue and this is the first extended stoplight for that" into "never stop heaven" whether you want to just continue through or hop on the highway by putting a bunch of roundabouts and a dogbone underpass in and removing left turns for most of the avenue. For proper city areas I'm almost certain better results would be achieved by using the space for any form of mass transit instead of more road. That and I shudder to think of roundabout traffic in a bumper to bumper scenario when one of the arteries out of the city gets blocked for 10 minutes (or months of construction).
wiredfool 5y ago
Roundabouts have better throughput in most cases, but have higher variance for time to complete transit, as one strong stream of cars from a single direction can choke off the alternative directions.

Roundabouts are fantastic for the low to mid traffic density case. When you get into proper city traffic density it can start to become very problematic, particularly if you don't have a good solution for pedestrians or cyclists to bypass each roundabout crossing. Even with that roundabouts tend to get a bit chaotic once they reach the point of "is expected to have a constant stream of cars in it for the next 2 hours" which can get particularly troublesome if the traffic in each direction is unbalanced and you get people awkwardly changing up yielding rules to let the one person going east-west in or that person tries to floor it to make it in an iffy gap. Also if you're relying on them as the only means of left turn (via u-turn) the wait times can significantly increase on busy roundabouts. That being said I absolutely love roundabouts in low/mid density areas. They finally converted the street I live on from 4 "pack cars into wait groups" stoplights and 1 "the highway just turned into an avenue and this is the first extended stoplight for that" into "never stop heaven" whether you want to just continue through or hop on the highway by putting a bunch of roundabouts and a dogbone underpass in and removing left turns for most of the avenue. For proper city areas I'm almost certain better results would be achieved by using the space for any form of mass transit instead of more road. That and I shudder to think of roundabout traffic in a bumper to bumper scenario when one of the arteries out of the city gets blocked for 10 minutes (or months of construction).

wiredfool 5y ago

Roundabouts have better throughput in most cases, but have higher variance for time to complete transit, as one strong stream of cars from a single direction can choke off the alternative directions.