On my way to work a bridge is being repaired. Today I was in the stream of traffic heading towards town, no cars going the other way. Mid stream the lights went red, just as I reached them. I went through. I reckon I travelled 100m between the lights and then about 600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but how big should the margin be?
Why when the lights have sensors do they never seem to be switched on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?

On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream of traffic heading towards town, no cars going the other way. Mid stream the lights went red, just as I reached them. I went through. I reckon I travelled 100m between the lights and then about 600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but how big should the margin be?
Why when the lights have sensors do they never seem to be switched on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors. However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road. When that
maximum is reached, the lights will change, even if no traffic has been
detected from that direction and there is still traffic coming from the
opposite direction. It is a precaution against sensor failure leaving
one direction permanently stopped. The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

--
--

Colin Bignell

On Mon, 05 Sep 2016 20:13:21 +0100, Nightjar wrote:

On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream of traffic heading towards town, no cars going the other way. Mid stream the lights went red, just as I reached them. I went through. I reckon I travelled 100m between the lights and then about 600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but how big should the margin be?
Why when the lights have sensors do they never seem to be switched on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors. However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road. When that
maximum is reached, the lights will change, even if no traffic has been
detected from that direction and there is still traffic coming from the
opposite direction. It is a precaution against sensor failure leaving
one direction permanently stopped. The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

That doesn't explain why the OP's light didn't switch back until 600m after he'd passed the other end. No traffic the other way means it must have gone red for him on the timer. But it should have changed back after the minimum get through time as there was traffic waiting behind the OP.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

Except if you're in a queue of traffic, there's no harm in following the car in front. It would also be stupid to stop if you'd moved over to the right to follow the queue, but passed the sign when they went red.

--
"Have you been hunting bear lately?"
"No, the grass tickles."

On Mon, 5 Sep 2016 20:13:21 +0100, Nightjar wrote:


Modern temporary traffic lights always use traffic sensors. However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

ISTR that at one time when they only exhibited a red and green that
wasn't the case then temporary traffic lights adopted the three lamp
Red Green Amber combinations so that they could be made compulsory.
The urban legend probably stems from the two lamp era, which leads to
wonder what if any offence may be commited if you ignore the geezer
with a Stop /Go board when he turns it to stop as you approach.

G.Harman

On Mon, 5 Sep 2016 20:13:21 +0100, Nightjar wrote:

On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream of traffic heading towards town, no cars going the other way. Mid stream the lights went red, just as I reached them. I went through. I reckon I travelled 100m between the lights and then about 600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but how big should the margin be?
Why when the lights have sensors do they never seem to be switched on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors.

Can traffic sensors always detect cycles?

However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road. When that
maximum is reached, the lights will change, even if no traffic has been
detected from that direction and there is still traffic coming from the
opposite direction. It is a precaution against sensor failure leaving
one direction permanently stopped. The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

"Scott" wrote in message
...
On Mon, 5 Sep 2016 20:13:21 +0100, Nightjar wrote:

On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream
of traffic heading towards town, no cars going the other way. Mid stream
the lights went red, just as I reached them. I went through. I reckon I
travelled 100m between the lights and then about 600m up the hill before
the lights changed.
I realise there has to be a margin to be sure a car gets through, but
how big should the margin be?
Why when the lights have sensors do they never seem to be switched on?
It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors.

Can traffic sensors always detect cycles?

I guess they could if the aimed them onto the pavements.



--
Adam

In article ,
misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream
of traffic heading towards town, no cars going the other way. Mid stream
the lights went red, just as I reached them. I went through. I reckon I
travelled 100m between the lights and then about 600m up the hill before
the lights changed. I realise there has to be a margin to be sure a car
gets through, but how big should the margin be? Why when the lights have
sensors do they never seem to be switched on? It just looks like a crude
timer is used. Under what circumstances are the sensors on the lights
used?

For at least the last 30 years, the use of sensors has been mandatory.

--
from KT24 in Surrey, England

On 05/09/2016 20:33, Scott wrote:

Modern temporary traffic lights always use traffic sensors.

Can traffic sensors always detect cycles?

Recent ones have IME.

On 05/09/2016 20:31, wrote:

wonder what if any offence may be commited if you ignore the geezer
with a Stop /Go board when he turns it to stop as you approach.


assuming they are properly authorised geezers, the same offence as
ignoring a red light. And some of those Stop/Go boards are fitted with
video cameras to provide evidence.

that is of course quite separate from the possible offence of ****ing of
the geezer's mates down the road who happen to have readily at hand
plenty of stones, shovels, dumper trucks, etc

--
Robin
reply-to address is (intended to be) valid

On Monday, September 5, 2016 at 8:36:44 PM UTC+1, charles wrote:
In article ,
misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream
of traffic heading towards town, no cars going the other way. Mid stream
the lights went red, just as I reached them. I went through. I reckon I
travelled 100m between the lights and then about 600m up the hill before
the lights changed. I realise there has to be a margin to be sure a car
gets through, but how big should the margin be? Why when the lights have
sensors do they never seem to be switched on? It just looks like a crude
timer is used. Under what circumstances are the sensors on the lights
used?

For at least the last 30 years, the use of sensors has been mandatory.

--
from KT24 in Surrey, England
I think the traffic lights here are just set on a timer and the sensors not used, and the timer is always way way longer than is needed to clear the lights.
So if I am approaching a set of these lights at red, and I am the only car on the road, how long should it take for them to show me a green?

On Monday, September 5, 2016 at 9:02:47 PM UTC+1, misterroy wrote:
On Monday, September 5, 2016 at 8:36:44 PM UTC+1, charles wrote:
In article ,
misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream
of traffic heading towards town, no cars going the other way. Mid stream
the lights went red, just as I reached them. I went through. I reckon I
travelled 100m between the lights and then about 600m up the hill before
the lights changed. I realise there has to be a margin to be sure a car
gets through, but how big should the margin be? Why when the lights have
sensors do they never seem to be switched on? It just looks like a crude
timer is used. Under what circumstances are the sensors on the lights
used?

For at least the last 30 years, the use of sensors has been mandatory.

--
from KT24 in Surrey, England
I think the traffic lights here are just set on a timer and the sensors not used, and the timer is always way way longer than is needed to clear the lights.
So if I am approaching a set of these lights at red, and I am the only car on the road, how long should it take for them to show me a green?

Found this on a govt site
"Vehicle Actuation (VA)
All equipment used on public roads must be capable
of working in Vehicle Actuated (VA) mode. These
signals use detectors to monitor traffic flows and
use this information to adjust the length of the signal
green time to reduce delays.
VA mode should always be used unless there is a
specific reason, such as using the manual mode
on a short-term basis to move plant into, or out of,
the controlled area. Use of VA will help to reduce
unnecessary delays.
If the signals are to be operated under manual
control at any time, both ends of the working area
should be clearly visible to the operator at all times.
Vehicle detectors (Microwave Vehicle Detectors, or
MVDs) used at portable traffic signals must have
received type approval from the Highways Agency.
To be able to work in the VA mode it is essential that
the MVDs are set up as detailed in the Pink Book1
.."

from https://www.gov.uk/government/upload...82498/2-11.pdf

In article ,
misterroy wrote:
On Monday, September 5, 2016 at 8:36:44 PM UTC+1, charles wrote:
In article ,
misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the
stream of traffic heading towards town, no cars going the other way.
Mid stream the lights went red, just as I reached them. I went
through. I reckon I travelled 100m between the lights and then about
600m up the hill before the lights changed. I realise there has to be
a margin to be sure a car gets through, but how big should the margin
be? Why when the lights have sensors do they never seem to be
switched on? It just looks like a crude timer is used. Under what
circumstances are the sensors on the lights used?

For at least the last 30 years, the use of sensors has been mandatory.

-- from KT24 in Surrey, England
I think the traffic lights here are just set on a timer and the sensors
not used, and the timer is always way way longer than is needed to clear
the lights. So if I am approaching a set of these lights at red, and I am
the only car on the road, how long should it take for them to show me a
green?

Temporary lights have switch for setting the distance between the two
ends. Perhasp this has been wrongly set because those who set them up don't
know the real distance and have set it to maximum.

--
from KT24 in Surrey, England

On 05/09/16 20:13, Nightjar wrote:
passing the 'If Red Light Shows Wait Here' sign, or the lights if there
is no sign, when the red light is showing is an offence.

The bloody lights themselves are an offence.


--
"If you dont read the news paper, you are un-informed. If you read the
news paper, you are mis-informed."

Mark Twain

It happens that misterroy formulated :
I think the traffic lights here are just set on a timer and the sensors not
used, and the timer is always way way longer than is needed to clear the
lights.
So if I am approaching a set of these lights at red, and I am the only car on
the road, how long should it take for them to show me a green?

Long enough for the lights at the far end to change to red, plus what
ever time it might take a slow vehicle to make it through and clear to
your end. It might be much longer, where the lights include a junction
and an extra road.

A factor of six allows for pushbikes going at one sixth the speed of your car.

On 05/09/2016 20:58, Robin wrote:

that is of course quite separate from the possible offence of ****ing of
the geezer's mates down the road who happen to have readily at hand
plenty of stones, shovels, dumper trucks, etc

During my brief career as a traffic liaison officer (stop go man) we
would note the time when a car ignored a red and the next morning look
out for him, then jump out and hold him up for ages. We also put bricks
inside a few of the roadcones to **** off the truckers who used to take
out a row of cones just for fun.

Bill

On 05-Sep-16 8:33 PM, Scott wrote:
On Mon, 5 Sep 2016 20:13:21 +0100, Nightjar wrote:

On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the stream of traffic heading towards town, no cars going the other way. Mid stream the lights went red, just as I reached them. I went through. I reckon I travelled 100m between the lights and then about 600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but how big should the margin be?
Why when the lights have sensors do they never seem to be switched on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors.

Can traffic sensors always detect cycles?

My car radar does and they use radar sensors to detect pedestrians
waiting at or crossing at lights controlled crossings, so I would think
they should. However, even if they don't, the maximum red cycle setting
will ensure that the lights change anyway.


However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road. When that
maximum is reached, the lights will change, even if no traffic has been
detected from that direction and there is still traffic coming from the
opposite direction. It is a precaution against sensor failure leaving
one direction permanently stopped. The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.


--
--

Colin Bignell

On 05-Sep-16 8:31 PM, wrote:
On Mon, 5 Sep 2016 20:13:21 +0100, Nightjar wrote:


Modern temporary traffic lights always use traffic sensors. However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

ISTR that at one time when they only exhibited a red and green that
wasn't the case then temporary traffic lights adopted the three lamp
Red Green Amber combinations so that they could be made compulsory.

Exactly so. Only two light temporary lights with the word POLICE between
the two lights (and usually on the stand) were compulsory. They were
taken to be an instruction to stop given by a police officer.

The urban legend probably stems from the two lamp era, which leads to
wonder what if any offence may be commited if you ignore the geezer
with a Stop /Go board when he turns it to stop as you approach.

Same as passing a red traffic light.

--
--

Colin Bignell

On 05-Sep-16 8:18 PM, James Wilkinson wrote:
On Mon, 05 Sep 2016 20:13:21 +0100, Nightjar wrote:
...The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

That doesn't explain why the OP's light didn't switch back until 600m
after he'd passed the other end. No traffic the other way means it must
have gone red for him on the timer. But it should have changed back
after the minimum get through time as there was traffic waiting behind
the OP.

It depends upon how fast he was going. At 60mph it would have taken him
less than 30 seconds to cover the distance.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

Except if you're in a queue of traffic, there's no harm in following the
car in front. It would also be stupid to stop if you'd moved over to
the right to follow the queue, but passed the sign when they went red.

Neither would provide you with a defence in Court.



--
--

Colin Bignell

On Tue, 06 Sep 2016 18:19:54 +0100, Nightjar wrote:

On 05-Sep-16 8:18 PM, James Wilkinson wrote:
On Mon, 05 Sep 2016 20:13:21 +0100, Nightjar wrote:
...The time before the lights change red
in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

That doesn't explain why the OP's light didn't switch back until 600m
after he'd passed the other end. No traffic the other way means it must
have gone red for him on the timer. But it should have changed back
after the minimum get through time as there was traffic waiting behind
the OP.

It depends upon how fast he was going. At 60mph it would have taken him
less than 30 seconds to cover the distance.

Didn't you know, you're supposed to drive fast through a red to minimize the chances of hitting something else.

Contrary to urban legend, temporary traffic lights are compulsory lights
and passing the 'If Red Light Shows Wait Here' sign, or the lights if
there is no sign, when the red light is showing is an offence.

Except if you're in a queue of traffic, there's no harm in following the
car in front. It would also be stupid to stop if you'd moved over to
the right to follow the queue, but passed the sign when they went red.

Neither would provide you with a defence in Court.

Clearly you check for pigs first. Anyway, it's no worse than speeding is it?

--
BREAKFAST.SYS halted... Cereal port not responding.

In article , Nightjar
writes
On 05-Sep-16 7:18 PM, misterroy wrote:
On my way to work a bridge is being repaired. Today I was in the
stream of traffic heading towards town, no cars going the other way.
Mid stream the lights went red, just as I reached them. I went
through. I reckon I travelled 100m between the lights and then about
600m up the hill before the lights changed.
I realise there has to be a margin to be sure a car gets through, but
how big should the margin be?
Why when the lights have sensors do they never seem to be switched
on? It just looks like a crude timer is used.
Under what circumstances are the sensors on the lights used?


Modern temporary traffic lights always use traffic sensors. However,
they also have a maximum length of red signal, which varies from 2-5
minutes, depending upon normal traffic flow on the road. When that
maximum is reached, the lights will change, even if no traffic has been
detected from that direction and there is still traffic coming from the
opposite direction. It is a precaution against sensor failure leaving
one direction permanently stopped. The time before the lights change
red in one direction and green in the opposite direction depends upon
traffic flow, speed limit through the works and the length of the works.

Contrary to urban legend, temporary traffic lights are compulsory
lights and passing the 'If Red Light Shows Wait Here' sign, or the
lights if there is no sign, when the red light is showing is an offence.

Unless it is snowing when it seems all such rules are suspended.
--
bert