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Its been nearly a week...

Community Veteran
Posts: 7,154
Thanks: 54
Fixes: 2
Registered: 30-08-2007

Its been nearly a week...

...since we had a motoring topic.
At a major road junction (in case you know it: A405 North Orbital Road with St Albans Road Watford) which has a a 4 way traffic light system -2 major roads cross and two right filters, each in their own sequence, this is a fairly common setup I think.
But at around 7ish in the morning, when I cross these lights for the first time of the day (of many) the timing of the lights is quite different to other times of day: each direction has no more than 10 seconds of green.
This sounds like a ridiculously short time, but d'you know it works very well, there's very little build up of traffic, as surprising number of vehicles can get through the lights (two lanes) I don't know what time this timing sequence begins or finishes, but I know that by 09:15 is back to "normal"
It has not just happened, its been like it for a couple of years, it seems some traffic planner somewhere has done his sums and actually got it right.
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2 REPLIES
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: Its been nearly a week...

I am guessing that someone educated in the topic has a full time job analysing traffic patterns at such junctions and adjusting settings for timing at different times of day. Or is it analysed by computer using those little cameras on the lights? Anyway it does appear to work well at some junctions I would regurarly pass through in Belfast.
On another traffic light topic, I used to ride a motorbike and work late shifts in a bar in Belfast. While travelling home in the small hours I passed through several junctions. As I am sure you know many junctions at night will have lights staying green for a certin direction unless a car pulls up to the red light at which time the lights will change. This is obviously caused by sensors. I worked out that the sensors in many cases could not detect a bike so I could easily wait at the red light with no other traffic in sight until the next day unless a car pulled up behind me. With those junctions I just ignored the red light and checked for approaching traffic. I was never caught by the police for doing this but I often wished I had been as I definitely had a good case. Anyone else experience this?
Community Veteran
Posts: 3,486
Registered: 02-10-2008

Re: Its been nearly a week...

I'm far from being an expert on traffic lights or traffic theory - but I have worked with people who are - and yes it it uses some quite complex maths I understand.
What I did work on was communication for two major cities traffic light / bus control systems. These are interconnected - so that buses get priority down the major thoroughfares. Just stand on the side of the street - or better still go for a ride on the bus and see how they can move down the street a good bit quicker, with lights changing to green just as they approach the lights.
In places like Manchester - for example Piccadily Gardens - and surrounding area, the system is linked into the Trams control system too, so they get priority.
And yes - I believe the normal sequence of lights is very dynamic and changes through out the day.
Sadly in my local town - this system is not in place and the lights can be very frustrating and they seemingly turn to red in front of any vehicle including buses  Angry
Regarding night time operation, I think the continental Europeans have a better system with their lights at quiet times such as overnight, they can go to flashing amber so nobody has priority and all have to exerise caution, and works well and no body gets held up.
Even in this country - when I have seen traffic lights fail - the traffic seems to cope will - and self regulates itself at many junctions..