Roger R wrote:

The length of the intergreen is determined by the particular circumstances.
Probabably the junction you mention has a high record of red light runners
or some other factor.


.... and of course as soon as the junction gets known for having this
long gap, more people start running the lights...


Andy

On Oct 22, 7:09 am, "Roger R" wrote:
"Matty F" wrote in message

...

Why do traffic engineers make you wait at the red light for 10 or more
seconds before the green light for the cross road changes to orange?

The waiting time for the lights to change that you describe is the period
between green ending one way and green appearing the other is known as the
intergreen period.

I'm not talking about the intergreen period. I'm talking about the
period from when the bus arrives at a red light until the green light
on an empty cross road changes to orange.
I maintain that that period should be zero seconds.
Nobody has come up with a good reason for that period to be. say, 10
seconds or more.

Adrian wrote:
Matty F gurgled happily, sounding much like they
were saying:

So, you are driving along at night and you reach traffic lights which
are red for you. Nobody else has been through the intersection for 10
minutes or more.
Why do traffic engineers make you wait at the red light for 10 or more
seconds before the green light for the cross road changes to orange?

I've never seen a set of traffic lights with a red period anywhere
_close_ to that.

Then yiou haven't looked.

Typically it avoids the need for a hugely dangerous pedestrian crossing
with lights 5 yards down the road. Which means yiou see those ligjhts go
green..when yours are red.

Anyway, its all ********. Every time they put in a set of lights
anywhere, congestion gets worse.

Matty F wrote:
On Oct 22, 7:09 am, "Roger R" wrote:
"Matty F" wrote in message

...

Why do traffic engineers make you wait at the red light for 10 or more
seconds before the green light for the cross road changes to orange?

The waiting time for the lights to change that you describe is the period
between green ending one way and green appearing the other is known as the
intergreen period.

I'm not talking about the intergreen period. I'm talking about the
period from when the bus arrives at a red light until the green light
on an empty cross road changes to orange.
I maintain that that period should be zero seconds.
Nobody has come up with a good reason for that period to be. say, 10
seconds or more.
'Ive got a pain in my diodes, all down the left hand side'...

On Oct 21, 5:51 am, "Arfa Daily" wrote:
In this case the bus company has paid for the traffic lights to be
installed. The traffic light controller knows perfectly well when a
bus has arrived. The traffic light engineer simply refuses to program
the lights correctly.
Let's say that there is supposed to be a bus exactly every 10 minutes,
and the trip actually takes nearly 10 minutes. An extra 10 or 20
seconds of wasted time on each trip can make the buses late all day.

I think I would have to suggest that, given all the variables that might
impede a bus's journey - old ladies with walking sticks and shopping bags
trying to clamber on, mothers with kids and push chairs, local authority /
gas board / water board etc digging up the road, weather conditions, people
with no change and so on - if a ten second delay at a set of lights could
screw up the timetable for the day, then the person that determined the
scheduling, got it wrong ...

It is necessary to keep to a precise published schedule, e.g. exactly
every 10 minutes or 12 minutes or 15 minutes. Times such as 11:00,
11:12, 11:24, 11:36 etc are published. No divisors other than 4, 5 or
6 divide evenly into 60 and give a result between 12 and 15.
The trip cannot be done in 10 minutes without speeding.
If the trip takes 15 minutes then not enough passengers can be carried
per hour to keep up the demand, so another vehicle (or larger) will be
needed at great expense. Therefore the trip must be done in 12 minutes
at most.
I used the term "bus" rather loosely!

The vehicle does not have a simple, ordinary accelerator:
http://i37.tinypic.com/slisg4.jpg

There are even more complications, involving the difficulty of the
vehicles passing each other. That may be done only at certain places,
at certain precise times!

"Matty F" wrote in message
...
On Oct 21, 5:51 am, "Arfa Daily" wrote:
In this case the bus company has paid for the traffic lights to be
installed. The traffic light controller knows perfectly well when a
bus has arrived. The traffic light engineer simply refuses to program
the lights correctly.
Let's say that there is supposed to be a bus exactly every 10 minutes,
and the trip actually takes nearly 10 minutes. An extra 10 or 20
seconds of wasted time on each trip can make the buses late all day.

I think I would have to suggest that, given all the variables that might
impede a bus's journey - old ladies with walking sticks and shopping bags
trying to clamber on, mothers with kids and push chairs, local authority
/
gas board / water board etc digging up the road, weather conditions,
people
with no change and so on - if a ten second delay at a set of lights could
screw up the timetable for the day, then the person that determined the
scheduling, got it wrong ...

It is necessary to keep to a precise published schedule, e.g. exactly
every 10 minutes or 12 minutes or 15 minutes. Times such as 11:00,
11:12, 11:24, 11:36 etc are published. No divisors other than 4, 5 or
6 divide evenly into 60 and give a result between 12 and 15.
The trip cannot be done in 10 minutes without speeding.
If the trip takes 15 minutes then not enough passengers can be carried
per hour to keep up the demand, so another vehicle (or larger) will be
needed at great expense. Therefore the trip must be done in 12 minutes
at most.
I used the term "bus" rather loosely!

The vehicle does not have a simple, ordinary accelerator:
http://i37.tinypic.com/slisg4.jpg

There are even more complications, involving the difficulty of the
vehicles passing each other. That may be done only at certain places,
at certain precise times!

Forgive my cynicism on this, but accepting that this is the theoretical
case, in any real world scenario, it is just not going to be realistically
possible to fulfil such a case. If there is no one at a bus stop, the bus
will sail on by, gaining perhaps as much as a minute on it's journey. If a
stop that would normally be calculated to take 30 seconds to load from,
today has a pensioners' outing waiting, this could cause the bus to lose
several minutes at that stop. Just missing a light, having to wait behind a
dustcart, trying to get past a cyclist on a narrow street, pulling over for
an ambulance, waiting at a PeLiCon crossing - the list of potential holdups
is endless. With the best will in the world, a bus timetable simply cannot
practically be accurate to parts of a minute, or probably even to a couple
of minutes at all stops on the route at all times of the day. At best, the
average scheduled times will be about correct, taken over several days, as
will the overall journey time of the route. Surely, correcting for these
small time discrepancies, is the purpose of the short turnaround break at
the terminus, used by the crew for a fag break ...

I accept that nominal timings which divide into an hour - if you are going
to have a timetable that reads "six minutes past the hour" etc - are
theoretically required, and that a number of buses per hour or whatever has
to be carefully considered to satisfy passenger demand, whilst still
remaining commercially viable on any route, but I absolutely dispute that it
is possible to run to such a tight schedule that a 10 second delay at a
traffic light, is going to wreck it.

Arfa

"The Natural Philosopher" wrote in message
...
Matty F wrote:
On Oct 22, 7:09 am, "Roger R" wrote:
"Matty F" wrote in message

...

Why do traffic engineers make you wait at the red light for 10 or more
seconds before the green light for the cross road changes to orange?

The waiting time for the lights to change that you describe is the
period
between green ending one way and green appearing the other is known as
the
intergreen period.

I'm not talking about the intergreen period. I'm talking about the
period from when the bus arrives at a red light until the green light
on an empty cross road changes to orange.
I maintain that that period should be zero seconds.
Nobody has come up with a good reason for that period to be. say, 10
seconds or more.
'Ive got a pain in my diodes, all down the left hand side'...



Wasn't it all the diodes in his left leg ... ? d;~)

Arfa

In article , Arfa Daily
wrote:

"Matty F" wrote in message
...

The vehicle does not have a simple, ordinary accelerator:
http://i37.tinypic.com/slisg4.jpg

There are even more complications, involving the difficulty of the
vehicles passing each other. That may be done only at certain places,
at certain precise times!

Forgive my cynicism on this, but accepting that this is the theoretical
case, in any real world scenario, it is just not going to be
realistically possible to fulfil such a case.
[snip
. . . has to be carefully considered to satisfy passenger demand,
whilst still remaining commercially viable on any route, but I
absolutely dispute that it is possible to run to such a tight schedule
that a 10 second delay at a traffic light, is going to wreck it.

Arfa
I guess you didn't look at the jpeg. Ah. timed at 02:29 that might explain
it :-)

--
John Mulrooney
NOTE Email address IS correct but might not be checked for a while.

Tidy desk tiny mind!

On Oct 22, 2:29 pm, "Arfa Daily" wrote:
"Matty F" wrote in message

I used the term "bus" rather loosely!

The vehicle does not have a simple, ordinary accelerator:
http://i37.tinypic.com/slisg4.jpg

There are even more complications, involving the difficulty of the
vehicles passing each other. That may be done only at certain places,
at certain precise times!

Forgive my cynicism on this, but accepting that this is the theoretical
case, in any real world scenario, it is just not going to be realistically
possible to fulfil such a case. If there is no one at a bus stop, the bus
will sail on by, gaining perhaps as much as a minute on it's journey. If a
stop that would normally be calculated to take 30 seconds to load from,
today has a pensioners' outing waiting, this could cause the bus to lose
several minutes at that stop.

There are basically no stops except at each end of the run. So, nobody
to wait for.

Just missing a light, having to wait behind a dustcart

There are no dustcarts because there are no houses for the entire run.

trying to get past a cyclist on a narrow street, pulling over for
an ambulance, waiting at a PeLiCon crossing -
the list of potential holdups is endless.

The "vehicles" have their own road that nobody else is allowed on, not
even pedestrians. The only possible delay is at the traffic lights,
where there is an unecessary 10 to 20 second delay. Every little time
saving helps.

"Tim W" wrote in message
...


Unless you're on blues & twos in which case you may process with caution
over steady red, but *never* over flashing red.

Not legally.
They can only exceed the speed limits legally.

"Huge" wrote in message
...
"dennis@home" wrote in message
...

Its the idiot drivers that make the long overlap necessary and they are
growing in numbers.
More cameras and stiffer fines is the easiest solution.

As usual, dennis is completely wrong. Real life experience shows that
traffic
light cameras *increase* accidents.


Go on then, prove it.
They sure don't increase the accidents caused by jumping the lights, they
may increase the accidents caused by idiots following too close, but you are
probably an expert on those.

dennis@home
wibbled on Friday 23 October 2009 19:28



"Tim W" wrote in message
...


Unless you're on blues & twos in which case you may process with caution
over steady red, but *never* over flashing red.

Not legally.
They can only exceed the speed limits legally.

But they do - and they will not be prosecuted for it unless they cause an
accident.

However, they *will* be prosecuted if caught going through a set of flashing
reds at a level crossing (or anywhere else flashing reds are used).

--
Tim Watts

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