"Tom Anderson" wrote in message
.li...

I was thinking about this a while ago, and i thought that
the best thing might be to use shape - build red lights
with two elements, an inverted triangle and a circle
enclosing it, like an upside-down version of this:

http://www.analyzemath.com/Geometry/...cumcircle2.gif

When you mean 'stop', light both bits; when you mean
'probably stop, but go if nobody's coming', you light the
triangle. The idea here is that the probably-stop light looks
like an illuminated version of the existing 'give way' sign,
which will hopefully trigger the right behaviour in drivers
who see it. And, since it's solid red, the main failure mode
is going to be to mistake it for a circular red, which is fine -
it's always safe to stop at a probably-stop. The downside, of
course, is that you need to build entirely new, and more complex, lights.

And that after a while, people would start mistaking stop lights for give
way lights, which isn't always safe.

All that said, isn't the real solution to make the lights
(or rather, the junction) sensor-controlled, or perhaps
better-sensor-controlled? If the junction knew there
was a queue of cars waiting to go one way, and cars
were only a few a minute the other way, it could just
change its lights to let them through.

I think bicycles fail to activate the sensors, which is one reason why
cyclists habitually jump red lights. Why are these sensors so rare anyway?
Are they very expensive?

Why has Britain never copied the Japanese idea of
having a digital countdown above traffic lights?
Surely it would increase capacity, and also give
drivers free time to have drinks or change CDs
instead of staring at the red light.

Maybe there's a worry that if people know they can go in 1
second, they'll go right now, since it's bound to be safe, isn't it ...

Some drivers do that already. As a driver, I usually watch the traffic
lights for crossing traffic and pedestrians, because they give me advance
warning of when my light will go green.

Incidentally, the other week I saw a car stop at a red light, and then
slowly roll forward at about 5cm/sec until his entire car was over the stop
line. At which point the camera above the traffic light flashed and he got a
100 pound fine and three points on his license. For some reason, that made
my day.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

John Rowland wrote:
"Tom Anderson" wrote in message
.li...

All that said, isn't the real solution to make the lights
(or rather, the junction) sensor-controlled, or perhaps
better-sensor-controlled? If the junction knew there
was a queue of cars waiting to go one way, and cars
were only a few a minute the other way, it could just
change its lights to let them through.

I think bicycles fail to activate the sensors, which is one reason
why cyclists habitually jump red lights. Why are these sensors so
rare anyway? Are they very expensive?

Good question. Back in the dark ages, when traffic levels were low,
many if not all traffic lights were controlled by rubber detector strips
set into metal frames on the road surface. Nowadays you can have either
movement detectors mounted on the lights, using presumably the same
cheap technology as in burglar alarm PIRs, or sensor wires embedded in
the top layer of the road surface. But most lights now seem to work on
a fixed time sequence.

When I lived just outside Reading, a busy cross roads near us was the
subject of Transport Research Laboratory investigations into different
phasing and sensor strategies. The final system was excellent in
responding very quickly to the actual traffic levels on each road. If
all the traffic queue in the green direction was cleared, the lights
immediately switched to the next phase. At quiet periods at night, all
lights were set to red, and an approaching vehicle would immediately
trigger a red+amber/green sequence for that direction. That was 15-20
years ago.

I'm sure the technology is cheap, and it shouldn't cause any more
disruption to install it as laying anti-skid coatings around signalled
junctions.

We also seem to have gone backwards on area control of a set of lights.
Do these schemes still exist in London? I keep being stopped,
particularly at light-controlled pedestrian crossings, in a way that sug
gests that each set of lights functions independently.
--
Richard J.
(to e-mail me, swap uk and yon in address)

"Richard J." wrote in message
o.uk...


We also seem to have gone backwards on area control of a set of lights.
Do these schemes still exist in London? I keep being stopped,
particularly at light-controlled pedestrian crossings, in a way that sug
gests that each set of lights functions independently.
--
Richard J.
(to e-mail me, swap uk and yon in address)

Perhaps there _is_ area control of the lights, but it is programmed to stop
you as often as possible?

Paul

"John Rowland" wrote in message
...
SNIP

When road works reduced my (straight) road to one lane, they put temporary
lights on it for a week, even though my road is habitually reduced to one
lane by parked cars anway.

--
John Rowland

I thought nearly ALL roads in Harrow were reduced to a single lane by parked
cars !!
Baz

"Richard J." wrote in message
o.uk...
MAJOR SNIP !!!

We also seem to have gone backwards on area control of a set of lights.
Do these schemes still exist in London? I keep being stopped,
particularly at light-controlled pedestrian crossings, in a way that sug
gests that each set of lights functions independently.
--
Richard J.

Have you noticed how many sets of light-controlled pedestrian crossings seem
to be able to activate without any pedestrian being anywhere near ? I
suspect its just another of these expensive but useless "traffic calming"
systems installed by stealth by those "who know best"
Baz

Paul Scott wrote in
:

"Richard J." wrote in message
o.uk...


We also seem to have gone backwards on area control of a set of
lights. Do these schemes still exist in London? I keep being
stopped, particularly at light-controlled pedestrian crossings, in a
way that sug gests that each set of lights functions independently.
--
Richard J.
(to e-mail me, swap uk and yon in address)

Perhaps there _is_ area control of the lights, but it is programmed
to stop you as often as possible?

What happened to that set of linked traffic lights on the A4 near Slough
that was programmed to let you through if you drove at 30 mph, but to ensure
that you hit every red light in turn if you drove slower than 25 or faster
than 35? Does that still exist?

"Richard J." wrote in message
o.uk...

We also seem to have gone backwards on area control
of a set of lights. Do these schemes still exist in London?
I keep being stopped, particularly at light-controlled
pedestrian crossings, in a way that suggests that
each set of lights functions independently.

I believe they still exist, but they can only work in one direction. If you
commute against the flow, you will likely get red after red.

Another thing - there is a pedestrian crossing in Kenton Road near the
Northwick Park roundabout which regularly goes red (to vehicles) even though
there are never any pedestrians anywhere near. Is this a malfunction or
design?

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

"Martin Underwood" wrote in message
...
SNIP

What happened to that set of linked traffic lights on the A4 near Slough
that was programmed to let you through if you drove at 30 mph, but to
ensure
that you hit every red light in turn if you drove slower than 25 or faster
than 35? Does that still exist?

I thought those lights were on the road from Uxbridge.
Baz

"John Rowland" typed


Another thing - there is a pedestrian crossing in Kenton Road near the
Northwick Park roundabout which regularly goes red (to vehicles) even though
there are never any pedestrians anywhere near. Is this a malfunction or
design?

I've not tried that one. Are you sure that it doesn't make pedestrians
wait so long that they cross long before the lights stop the traffic?
There are certainly some on heavily-used routes that keep pedestrians
waiting inordinately long. (Finchley Road (A41) just south of Platts
Lane/Fortune Green Rd is one such example.)

--
Helen D. Vecht:
Edgware.

"Helen Deborah Vecht" wrote in message
...
"John Rowland" typed

Another thing - there is a pedestrian crossing in Kenton
Road near the Northwick Park roundabout which regularly
goes red (to vehicles) even though there are never any
pedestrians anywhere near. Is this a malfunction or design?

I've not tried that one. Are you sure that it
doesn't make pedestrians wait so long that
they cross long before the lights stop the traffic?

I thought that the first few times, but I've been stopped by it about 100
times this year, and I don't think I have ever seen a pedestrian in this
road at all.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes