Queens Rd Traffic Scheme

[dave_the_m 61]

5 hours ago, Fudbeer said:

I don't understand how what is effectively a timed arrow/cross over a lane can be that expensive to maintain.

Well for one thing its not a single arrow but a whole series of arrows spread over several hundred yards, which must all act in union with suitable locksteps, and which must all fail in a safe way. Then there's the fact that the equipment is 30 years old, is of a rare type (unlike traffic traffic lights for example), and for which off-the-shelf spares may no longer be available. And at that age many things, including electrical connections,  may be starting to corrode and/or fail. Finding where the fault is can be non-trivial, and repairs may involve closing lanes and getting in there with a cherry picker, or in a bad case, digging up the road to get to a failed cable. And while the fault isn't yet fixed, one lane is unusable.

 

Etc etc.

[Planner1 437]

5 hours ago, Fudbeer said:

One of their few road systems that works so they get rid!

 

I don't understand how what is effectively a timed arrow/cross over a lane can be that expensive to maintain.

It works reasonably well but is not without its problems.

 

There are collisions caused by drivers who visit premises on the  route  and, when they come back onto the tidal flow system,  assume that the lane configuration is the same as when they went in, which, when the lane configuration has changed in the meantime, can bring them into conflict with other traffic, resulting in collisions. There have also been cases of drivers who are looking up at the gantries not seeing the traffic signals at the junctions along the route and then running the red lights causing collisions (note the presence of a red light camera at the Myrtle Rd junction, which is here because of the number of red light running collisions).  

 

Doing any work on the light up signs on the overhead gantries is a problem, as it needs lane closures. The gantries are old as is the control gear that runs the system.  It isn't compliant with modern standards.

[Guest]

9 hours ago, dave_the_m said:

Well for one thing its not a single arrow but a whole series of arrows spread over several hundred yards, which must all act in union with suitable locksteps, and which must all fail in a safe way. Then there's the fact that the equipment is 30 years old, is of a rare type (unlike traffic traffic lights for example), and for which off-the-shelf spares may no longer be available. And at that age many things, including electrical connections,  may be starting to corrode and/or fail. Finding where the fault is can be non-trivial, and repairs may involve closing lanes and getting in there with a cherry picker, or in a bad case, digging up the road to get to a failed cable. And while the fault isn't yet fixed, one lane is unusable.

 

Etc etc.

Don't be sensible! What are the people that know nothing about how the system works or any of the actual infrastructure behind it and think it's as simple as the lights in their homes going to complain about?! I mean they drive past it every day (every day! even Christmas Day!) so they know better.

[Jack_Russell 11]

When Heeley bridge was rebuilt in the year 2000, it was rebuilt (on the cheap?) with only 2 lanes of traffic, there are three over head gantrys, (which are still there) two near Ponsfords before the bridge and one just after the bridge, these haven't been used in years.

[Cyclone 10]

19 hours ago, dave_the_m said:

Well for one thing its not a single arrow but a whole series of arrows spread over several hundred yards, which must all act in union with suitable locksteps, and which must all fail in a safe way. Then there's the fact that the equipment is 30 years old, is of a rare type (unlike traffic traffic lights for example), and for which off-the-shelf spares may no longer be available. And at that age many things, including electrical connections,  may be starting to corrode and/or fail. Finding where the fault is can be non-trivial, and repairs may involve closing lanes and getting in there with a cherry picker, or in a bad case, digging up the road to get to a failed cable. And while the fault isn't yet fixed, one lane is unusable.

 

Etc etc.

Operating in lockstep is fairly trivial though isn't it.  Two circuits (one for each possible configuration), each circuit powers every bulb in requires and the two circuits share a switched live, so it's only ever possible to power one of them at a time.

Probably not how it actually works, but it's that simple.

 

[dave_the_m 61]

2 hours ago, Cyclone said:

Operating in lockstep is fairly trivial though isn't it.  Two circuits (one for each possible configuration), each circuit powers every bulb in requires and the two circuits share a switched live, so it's only ever possible to power one of them at a time.

Probably not how it actually works, but it's that simple.

 

Suppose there's water or animal ingress or a loose/corroded wire which causes a short between the two switched circuits and both sets of lights come on? Such a short wouldn't trigger a circuit breaker since it's neither an over-current nor an earth fault.

 

Also, such arrangements don't normally have a switched live cable running for hundreds of yards and visiting every gantry - it would be impossible (without excessively large cables) to maintain the earth fault loop impedance to a low enough level for circuit breakers to trip on a fault. Instead, its likely that a low-current control signal feeds relays at each gantry which operate the actual lamps.

 

In short, these things are usually a lot more complex than they appear.

[Guest]

3 hours ago, Cyclone said:

Operating in lockstep is fairly trivial though isn't it.  Two circuits (one for each possible configuration), each circuit powers every bulb in requires and the two circuits share a switched live, so it's only ever possible to power one of them at a time.

Probably not how it actually works, but it's that simple.

 

You're still assuming that the system requires no maintenance and runs perfectly 100% of the time.

[Cyclone 10]

2 hours ago, dave_the_m said:

Suppose there's water or animal ingress or a loose/corroded wire which causes a short between the two switched circuits and both sets of lights come on? Such a short wouldn't trigger a circuit breaker since it's neither an over-current nor an earth fault.

 

Also, such arrangements don't normally have a switched live cable running for hundreds of yards and visiting every gantry - it would be impossible (without excessively large cables) to maintain the earth fault loop impedance to a low enough level for circuit breakers to trip on a fault. Instead, its likely that a low-current control signal feeds relays at each gantry which operate the actual lamps.

 

In short, these things are usually a lot more complex than they appear.

Yes, you're quite right.  Simple in theory, but more complex when scaled up and when you take fault conditions into account.

A modern system would almost certainly be digital.

2 hours ago, probedb said:

You're still assuming that the system requires no maintenance and runs perfectly 100% of the time.

No I wasn't.

[*_ash_* 88]

I accept the responses from the maintenance knowledge people, and that's it's old expensive to maintain etc. now.

 

However, like traffic light systems, I struggle to understand why much better systems to traffic flow aren't achievable in today's world. 

 

 

 

 

Edited June 13, 2019 by *_ash_*

[*_ash_* 88]

I seem to spend half my working day at some red lights. Snig Hill being probably number 1 spot.

 

I'm going to be charged £12.50 per day for polluting the city in my taxi soon, and I just sit at these lights now (with nothing else wanting to go anywhere, it's not heavy traffic!!) and wonder how much less emissions I would give out, if traffic flow was better. Spend the £42 million on traffic lights that are intelligent. (or more intelligent! ) can't be that hard. I thought we lived in a tech world.

 

 

[Penistone999 10]

On 12/06/2019 at 13:12, Planner1 said:

It works reasonably well but is not without its problems.

 

There are collisions caused by drivers who visit premises on the  route  and, when they come back onto the tidal flow system,  assume that the lane configuration is the same as when they went in, which, when the lane configuration has changed in the meantime, can bring them into conflict with other traffic, resulting in collisions. There have also been cases of drivers who are looking up at the gantries not seeing the traffic signals at the junctions along the route and then running the red lights causing collisions (note the presence of a red light camera at the Myrtle Rd junction, which is here because of the number of red light running collisions).  

 

Doing any work on the light up signs on the overhead gantries is a problem, as it needs lane closures. The gantries are old as is the control gear that runs the system.  It isn't compliant with modern standards.

No , its there to raise revenue ,just like the rest of the councils cameras. 

[Pettytom 1]

21 minutes ago, Penistone999 said:

No , its there to raise revenue ,just like the rest of the councils cameras. 

Yes, but it raises revenue from the stupid, the  inobservant and the criminally minded. What’s not to like?