03-08-2019, 11:21 AM
(03-08-2019, 09:13 AM)danbrotherston Wrote: They won't increase throughput if they're constantly jammed up, but they won't ever be "constantly" jammed up, some straight cars will get through, which is why it increases the capacity of the intersection.
This is why our regional engineers saw fit to reconfigure Westmount/Glasgow intersection to four straight lanes no turn lanes from the previous configuration, even though that configuration was used before and was known to be unsafe, because it did in theory and practice carry more cars. Also prioritized over safety in this case is continuing unnecessary access (the intersection could have had turn restrictions) and keeping wealthy property owners happy (the property owners objected to widening the road to put in turn lanes).
I’m saying throughput is lower, in particular at Westmount/Glasgow but also in other locations, then it would be with 2-lane roads with turn lanes. If Westmount near Glasgow was changed to 2 lanes with turning lanes, the intersection would be the same width on either side of Glasgow (from right to left the four lanes would be: right turn, straight through, left turn, opposite direction), just offset by one lane. Elsewhere it would obviously be much narrower, being only a 2-lane road.
Have they actually measured it to carry more cars? I doubt it. I’ve been stuck northbound on Westmount with multiple people trying to turn left — so the left turn lane has a capacity of approximately 0. Meanwhile, the right lane doesn’t even have a full lane’s capacity, because every time somebody tries to turn right at the same time that people are walking across Glasgow, the car waiting to turn right holds up traffic on Westmount. Sometimes there will be people trying to turn left in both directions; but neither can see whether there is any straight through traffic, so they both just end up waiting. It’s an appalling design, and I’m not even talking about the impact on pedestrians (although I care about that too): it’s shockingly bad for vehicular traffic. If we’re going to have only a single lane’s capacity, we might as well save the money and only build a single lane.