09-03-2013, 08:28 AM
Traffic signals are often put in for reasons other than driver convenience.
The two most common reasons are:
Pedestrian safety and convenience
Traffic management (improving flow to a particular direction)
In general car driver requirements are considered much lower than buses, pedestrians and cyclists
Part time signals are not very common because while they are off the accident rate tends to go up. Sandygate M5 Junction 30 was a prime example installed as part time but running full time.
The most common part time signals you tend to see now are Ramp metering installations.
http://www.direct.gov.uk/prod_consum_dg/...185831.pdf
In towns and cities most traffic signals are connected to a SCOOT UTC system
http://www.scoot-utc.com/
UTC systems have been common in the UK since the early 1980's and SCOOT since the Late 1980's
Junction that are standalone or more rural use an alternative system called MOVA
http://www.trl.co.uk/software/software_p...k/mova.htm
Individual sets of signals or those where the UTC or MOVA has gone offline fall-back to another strategy depending upon location and time of day.
These can be:
VA Vehicle actuation (the most common fall-back)
FT Fixed time
CLF Cable-less linking facility (usually used where several signals are close together in large towns or cities)
All of the above strategies may be over ridden by Bus Priority (just as it sounds) Hurry Call (usually used by emergency vehicles such as fire engines)
None of these things mean that a given installation will work or that traffic flows will improve, I just depends what the Traffic Engineer intended and if he was able to achieve his aim.
A recent example is Canford Bottom which is a Hamburger and Runs MOVA
http://www.highways.gov.uk/roads/road-pr...nt-scheme/
The locals hate it they now have to wait (up a 90 seconds in some cases) but the flow on the A31 has massively improved, I used to avoid this road due to the long queues on the A31 now you just sail through.
Knowing how signals operate can give you a good clue as to junctions to avoid!
Cheers
Mike T
The two most common reasons are:
Pedestrian safety and convenience
Traffic management (improving flow to a particular direction)
In general car driver requirements are considered much lower than buses, pedestrians and cyclists
Part time signals are not very common because while they are off the accident rate tends to go up. Sandygate M5 Junction 30 was a prime example installed as part time but running full time.
The most common part time signals you tend to see now are Ramp metering installations.
http://www.direct.gov.uk/prod_consum_dg/...185831.pdf
In towns and cities most traffic signals are connected to a SCOOT UTC system
http://www.scoot-utc.com/
UTC systems have been common in the UK since the early 1980's and SCOOT since the Late 1980's
Junction that are standalone or more rural use an alternative system called MOVA
http://www.trl.co.uk/software/software_p...k/mova.htm
Individual sets of signals or those where the UTC or MOVA has gone offline fall-back to another strategy depending upon location and time of day.
These can be:
VA Vehicle actuation (the most common fall-back)
FT Fixed time
CLF Cable-less linking facility (usually used where several signals are close together in large towns or cities)
All of the above strategies may be over ridden by Bus Priority (just as it sounds) Hurry Call (usually used by emergency vehicles such as fire engines)
None of these things mean that a given installation will work or that traffic flows will improve, I just depends what the Traffic Engineer intended and if he was able to achieve his aim.
A recent example is Canford Bottom which is a Hamburger and Runs MOVA
http://www.highways.gov.uk/roads/road-pr...nt-scheme/
The locals hate it they now have to wait (up a 90 seconds in some cases) but the flow on the A31 has massively improved, I used to avoid this road due to the long queues on the A31 now you just sail through.
Knowing how signals operate can give you a good clue as to junctions to avoid!
Cheers
Mike T
It's rare and desirable
