Leading vs. Trailing green arrow at traffic intersections
Leading vs. Trailing green arrow at traffic intersections
Anyone here have a good idea as to why some cities have a leading green left arrow, and some have a trailing green left arrow at traffic intersections? It seems to me that the throughput would be the exact same. Why is there no universal standard? Only thing I can think of is that it must be a safety issue.
Presumably it is to do with optimizing traffic flow.
One design problem they have is when you want to turn right on a red light, there is usually nothing to indicate whether the oncoming traffic has a green turn left arrow (so they are entering the same road as you) so you don't know who has priority.
One design problem they have is when you want to turn right on a red light, there is usually nothing to indicate whether the oncoming traffic has a green turn left arrow (so they are entering the same road as you) so you don't know who has priority.
Re: Leading vs. Trailing green arrow at traffic intersection
A trailing arrow is preferred if the left turn lane is short, especially when there is a physical barrier such as a bumped out median. Otherwise left turning vehicles get stuck in line behind cars going straight and are unable to reach the turn position until too late.Sirrip wrote:Anyone here have a good idea as to why some cities have a leading green left arrow, and some have a trailing green left arrow at traffic intersections? It seems to me that the throughput would be the exact same. Why is there no universal standard? Only thing I can think of is that it must be a safety issue.
Trailing green arrows are a good way for left-turning folks to be broad-sided by oncoming folks running the red light. With leading green arrows, the oncoming traffic has been sitting stopped waiting for the cross traffic.
With significant left-turning traffic, a 4-way intersection, might have each way go separated for a sequence of 4 light groups.
With significant left-turning traffic, a 4-way intersection, might have each way go separated for a sequence of 4 light groups.
Leading green arrows are a good way for left turning folks to be broadsided by traffic running the red light on the cross street, which are harder to see and avoid.livesoft wrote:Trailing green arrows are a good way for left-turning folks to be broad-sided by oncoming folks running the red light. With leading green arrows, the oncoming traffic has been sitting stopped waiting for the cross traffic.
With significant left-turning traffic, a 4-way intersection, might have each way go separated for a sequence of 4 light groups.