Abbeydale Rd South/ Abbey Lane Traffic Signal Junction

A revised junction and traffic signal arrangement was introduced at this location during 2003. This involved considerable widening of the junction on Abbey Lane, and significant revisions to the traffic signals to improve the operation for right turning traffic, and improve the safety of the junction.

A number of queries have been raised in relation to how the junction operates; possible alternatives that people have considered would be of benefit; and about levels of traffic flows and delays.

Q.3 Since you haven't been able to provide right turn signals, how is the redesigned junction any better than the previous arrangement?

A.3 Since we decided that right turn signals would not work, we had to find some other way to improve conditions for right turning vehicles. We found that we could do this in two ways by altering the junction so that:

1 all right turning vehicles have a considerably improved visibility of traffic coming towards them in the opposite direction. This allows them to judge gaps in the traffic flow and make it safer and easer to make their turn. This is particularly important, as we believe that poor visibility was one of the major factors in many of the previous accidents involving right turning vehicles at this junction.

2 There is an area within the centre of the junction where right turning vehicles can wait safely (without coming into conflict with opposing vehicles), so that if they are unable to turn during the green signal, they can safely complete their turn at the end of the traffic stage after the signals have changed to red.

Q.4 Surely you aren't allowed to turn right when the signals have turned to red? Isn't this illegal?

A.4 Actually it is both legal and sensible to turn right from the middle of the junction when the signals have turned to red. Perhaps it would help to think about a more standard traffic signal crossroads (for example - the Abbeydale Road/ Bannerdale Road junction - which is not very far away). These types of junctions don't have any special signals for right turning vehicles. If you think about the standard situation for rivers turning right, they cross the signal stop line on green and if traffic is busy, they come to a stop in the middle of the junction to wait for a gap in the opposing traffic so that they can complete their turn. If traffic is busy, which is not uncommon, the driver may have to wait until the signals have turned to red and opposing traffic has stopped before they are able to complete the turn. This is perfectly legal. The key point here is that it is only illegal to cross a signal stop line on a red signal; once you have entered into the junction, completing your turn during the period before traffic starts on the next signal stage is both legal and normal practice.

This situation applies in exactly the same way at the Abbeydale Road South/ Abbey Lane junction. As long as vehicles do not cross the signal stop - line on their approach when a red signal is showing, it is both legal and normal practice to complete the right turn from the centre of the junction is that the design of the junction takes advantage of this time by creating larger areas within the junction for vehicles to stand and complete their right turn movement.

In order to make this situation even safer, the traffic lanes within the junction have been positioned in a ‘non hooking' layout, so that opposing right turners can proceed at the same time during this period, with good visibility of each other. Special vehicle detectors have also been provided in the road surface to extend the ‘all red' period before the next signal stage starts if there are a number of vehicles waiting to make a right turn from the lanes in the middle of the junction.

Q.5 Wouldn't the time that you use to extend the ‘all red' period be better used to provide right turn signals?

A.5 Actually the time required to extend the ‘all red' period between the two main vehicle stages ( this extension period generally runs twice in every signal cycle) is much less than would be required to run any right turn green signals. The extended all red periods can add up to about 12 seconds in each signal cycle. By contrast, four right turn green arrow signal stages would typically add at least 60 seconds to every cycle. This is a considerable difference in ‘lost' green time- and it would have a major effect on the capacity of the junction, causing extensive queuing on the approaches.

As a result of a meeting I had with high ways board the admendments that will be taking place are as follows.

The bus lane on Abbeydale road South will be removed and a bus monitor will be installed at the traffic lights. As a result of this the traffic on Abbbeydale road South will not have to go on to the left hand lane then try to get back into the right hand lane. The bus monitor that is to be installed will only work on morning traffic, to allow a smooth flow of traffic from Totley to town.

Janet Chapman