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