Description
Southbound on South Prospect St., the left arrow goes on but the straight arrow stays red when there is apparently no reason that traffic shouldn't go. (If there are pedestrians crossing the south side of Main St. and S. Prospect St., that would be a good reason, but there were not). It would improve traffic flow if the straight green arrow did not have to have a separate cycle.
5 Comments
Acknowledged DPW Pine Customer Service (Verified Official)
Traffic Signal Engineer (Verified Official)
Traffic Signal Engineer (Verified Official)
Yes, this has been brought up before, and is how it would be set up conventionally. We live in a city full of oddities and artifacts - this is one of them. Short answer is that during the southbound left turn (SBLT), the south crosswalk is active. Long answer below:
The topic of SBLT simultaneous with SB through comes up every once in a while. It is a fair question. Current operation appears counter intuitive, but there are a couple of advantages to it. If we start SBLT and SB through simultaneously (conventionally), we would start the westerly, concurrent crosswalk too. We would give the west crosswalk an advance walk of at least seven seconds to protect against SB right turns. Meaning SB through would see red for seven seconds while SBLT is going. So nominally we start off with the same thing.
In the current operation these two movements are clearly separated. There is no difference of signal operation presented to SB traffic whether the pedestrian button was pushed (SB red) or not (SB green). The SBLT arrows would be green in either case. Lack of ambiguity in signal operation is a good thing.
With simultaneous SB and SBLT, and a pedestrian call for the west crosswalk, the soonest we could get SB through traffic moving versus the current operation is 12 seconds earlier, which sounds good. However, if the first car in line wants to turn right and there are a lot of pedestrians crossing, which is pretty frequent, the 12-second advantage starts to shrink.
Another problem with simultaneous operation is that the diagonal pedestrian movement is no longer possible. Eliminating this possibility would require some prominent signs to warn of a change in operation. Some people experienced with the diagonal crossing might not catch onto the new operation, despite the signs, and walk into oncoming traffic. If simultaneous operation started with the new signal installation in 2000, no problem. Sixteen years later, with no visible change other than a couple of signs, and the diagonal crossing accepted and ingrained by now, a change is more difficult and worrisome to implement.
The advantages of the current operation:
* West crosswalk is fully protected for a full phase (movement), not just part of it (seven seconds).
* West crosswalk gets first shot at crossing after Main Street signals turn red, which is intuitive for waiting pedestrians.
* Unusual ability at a large, busy intersection for pedestrians to cross diagonally, yet safely.
* No ambiguity for SB approach whether the pedestrian button was pushed (SB red) or not (SB green), which could cause false starts, and perhaps rear-enders.
Switching to a simultaneous SB and SBLT operation is not as expensive as some modifications, requiring just time, cable, and signs. A simultaneous SB and SBLT operation is not necessarily a complete win-win versus the current operation, and the possible disadvantages it creates. Therefore, for now, it makes sense to continue with the current operation.
The Department of Public Works has resolved this request. Thanks for helping to keep Burlington a great place to live and work.
Closed Traffic Signal Engineer (Verified Official)
Traffic Signal Engineer (Verified Official)