(Richard M Willis) wrote the
following in: om

Aside: does anyone know why some traffic signals here show a
green filter arrow *AND* a solid green light simultaneoulsy,
given that the latter allows a superset of the filtered traffic
to "go". ?

I can think of one traffic light where a green light means you can go
forward and turn right if no traffic is coming from the opposite
direction, but a green light *and* green arrow mean that there is a red
light for traffic coming the opposite direction so you can turn right
without needing to worry about oncoming traffic.

--
message by Robin May. Inimitable, but would you want to anyway?
"GIVE IN! IT'S TIME TO GO!" - The NHS offers a high standard of care.

http://robinmay.fotopic.net
Spelling lesson: then and than are different words.

Robin May wrote in message

[about my "superfluous green arrow" question]

I can think of one traffic light where a green light means you can go
forward and turn right if no traffic is coming from the opposite
direction, but a green light *and* green arrow mean that there is a red
light for traffic coming the opposite direction so you can turn right
without needing to worry about oncoming traffic.

Yes, I know that's the case in practice: a green arrow meaning that
the opposing flow is on RED.

However, my point is that there is no legal distinction between
"solid" and "solid+arrow": the driver facing those aspects should
behave the same in both cases (i.e. assume nothing about conflicting
flows and know only that he is not compelled to stop by the signal
alone).

The presence of this superfluous combination of signals causes far too
many
people to think that they must stop UNLESS they have a filter, i.e.
that
the solid green applies only to movements that don't have a filter
even
if that filter is currently dark.

Who ever thought traffic lights can be so interesting and varied !
We've had
examples from various US States, various Canadian provinces, the two
Germanies,
Italy, France, Holland and several of those seem to conflict.

Perhaps we should allow overtaking on the left as well. The USAns seem
to manage it.

Richard [in PO7]

Richard M Willis wrote:
Robin May wrote in message

[about my "superfluous green arrow" question]

I can think of one traffic light where a green light means you can
go forward and turn right if no traffic is coming from the opposite
direction, but a green light *and* green arrow mean that there is
a red light for traffic coming the opposite direction so you can
turn right without needing to worry about oncoming traffic.

Yes, I know that's the case in practice: a green arrow meaning that
the opposing flow is on RED.

However, my point is that there is no legal distinction between
"solid" and "solid+arrow": the driver facing those aspects should
behave the same in both cases (i.e. assume nothing about conflicting
flows and know only that he is not compelled to stop by the signal
alone).

There's a general need for caution at junctions in case other drivers
behave unpredictably, but nevertheless it is reasonable to assume that
when the green arrow is shown it is safe to turn right provided that any
oncoming vehicle would be able to stop in time to avoid colliding with
you (i.e. not storming towards you at 50 mph with no sign that it will
stop).

I was amazed to find that there is nothing in the Highway Code about the
green solid+arrow indication.

The presence of this superfluous combination of signals causes far
too many people to think that they must stop UNLESS they have a
filter,
i.e. that the solid green applies only to movements that don't have a
filter even if that filter is currently dark.

Can't say I have noticed that, but then London is a different driving
experience to rural Hampshire.

--
Richard J.
(to e-mail me, swap uk and yon in address)

In message , Richard J.
writes
Can't say I have noticed that, but then London is a different driving
experience to rural Hampshire.
London is a different driving experience to anywhere.
--
Clive

(Richard M Willis) wrote in
m:

The presence of this superfluous combination of signals causes far
too many
people to think that they must stop UNLESS they have a filter, i.e.
that
the solid green applies only to movements that don't have a filter
even
if that filter is currently dark.

As I understand it, you DO have to stop if the filter isn't showing in
one situation: if the filter light is to the immediate left or right of
the main light, rather than underneath it.

I was led to believe that the law regarding filter arrows is thus:

* If the filter arrow is below the main green light, then if the main
light is illuminated but the filter isn't, you may proceed across the
stop line and wait to turn when it is safe to do so. Once the filter
arrow illuminates you can assume it IS safe to do so as the oncoming
traffic will now be on a red.

* If the filter arrow is beside the main green light, then if the main
light is illuminated but the filter isn't, you must not cross the stop
line, even if it is safe to turn. You must wait for the filter to
illuminate before you can even begin to make the turn.

Interestingly enough I can't find anything in the Highway Code to back
up this belief, despite the fact that a few years back a friend failed
his car test and the examiner told him that one of the faults was to
edge forward at a beside-the-main-light filter.

--
Iain | PGP mail preferred: pubkey @ www.deepsea.f9.co.uk/misc/iain.asc
($=,$,)=split m$"13/$,qq;13"13/tl\.rnh r HITtahkPctacriAneeeusaoJ;;
for(@==sort@$=split m,,,$,){$..=$$[$=];$$=$=[$=];$@=1;$@++while$=[--$=
]eq$$&&$==$?;$==$?;for(@$){$@--if$$ eq$_;;last if!$@;$=++}}print$..$/

Iain wrote:
(Richard M Willis) wrote in
m:

The presence of this superfluous combination of signals causes far
too many people to think that they must stop UNLESS they have a
filter, i.e. that the solid green applies only to movements that
don't have a filter even if that filter is currently dark.

As I understand it, you DO have to stop if the filter isn't showing
in one situation: if the filter light is to the immediate left or
right of the main light, rather than underneath it.

There is no such rule (see below).

I was led to believe that the law regarding filter arrows is thus:

* If the filter arrow is below the main green light, then if the
main light is illuminated but the filter isn't, you may proceed
across the stop line and wait to turn when it is safe to do so.
Once the filter arrow illuminates you can assume it IS safe to do
so as the oncoming traffic will now be on a red.

Correct.

* If the filter arrow is beside the main green light, then if the
main light is illuminated but the filter isn't, you must not cross
the stop line, even if it is safe to turn. You must wait for the
filter to illuminate before you can even begin to make the turn.

If the traffic light looks like this:

Red
Amber
Green Green-arrow

then you are free to move if the solid green is lit. It would be absurd
to expect drivers to notice the position of a light which is not lit,
especially at night.

Interestingly enough I can't find anything in the Highway Code to
back up this belief, despite the fact that a few years back a
friend failed his car test and the examiner told him that one of
the faults was to edge forward at a beside-the-main-light filter.

That was probably a junction where there is a separate complete traffic
signal controlling turning traffic. In other words, you have something
like this:

Red Red
Amber Amber
Green Green-arrow

In that case, the two clusters control different lanes. Perhaps your
friend was waiting in the right-hand lane, and moved forward when the
left lane's green was lit, thus passing a red light for his lane. Do
you know which junction it was?

--
Richard J.
(to e-mail me, swap uk and yon in address)

"Iain" wrote in message
...
(Richard M Willis) wrote in
m:

As I understand it, you DO have to stop if the
filter isn't showing in one situation: if the filter
light is to the immediate left or right of
the main light, rather than underneath it.

I was led to believe that the law regarding
filter arrows is thus:

* If the filter arrow is below the main green light,
then if the main light is illuminated but the filter
isn't, you may proceed across the stop line
and wait to turn when it is safe to do so.
Once the filter arrow illuminates you can
assume it IS safe to do so as the oncoming
traffic will now be on a red.

* If the filter arrow is beside the main green light,
then if the main light is illuminated but the filter
isn't, you must not cross the stop line, even if
it is safe to turn. You must wait for the filter to
illuminate before you can even begin to make
the turn.

I'm sorry, but I think this is not correct. When TPTB want all right-turning
traffic to wait regardless of oncoming flows, they use a red light with a
forward green filter (and a left filter as well if necessary). Perhaps this
is the scenario where your friend failed his test (described below.)

IME right filter lights are only beneath the other lights when on a traffic
island which is very narrow.

Interestingly enough I can't find anything in the
Highway Code to back up this belief, despite
the fact that a few years back a friend failed
his car test and the examiner told him that
one of the faults was to
edge forward at a beside-the-main-light filter.

--
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

In article , Iain
writes
The presence of this superfluous combination of signals causes far
too many
people to think that they must stop UNLESS they have a filter, i.e.
that
the solid green applies only to movements that don't have a filter
even
if that filter is currently dark.

As I understand it, you DO have to stop if the filter isn't showing in
one situation: if the filter light is to the immediate left or right of
the main light, rather than underneath it.

Not so.

I was led to believe that the law regarding filter arrows is thus:

Here's what the law actually says:

====
Significance of light signals prescribed by regulations 33 to 35

36. - (1) The significance of the light signals prescribed by
regulations 33, 34 and 35 shall be as follows -

(a) subject to sub-paragraph (b) and, where the red signal is shown at
the same time as the green arrow signal, to sub-paragraphs (f) and (g),
the red signal shall convey the prohibition that vehicular traffic shall
not proceed beyond the stop line;

(b) when a vehicle is being used for fire brigade, ambulance, bomb or
explosive disposal, national blood service or police purposes and the
observance of the prohibition conveyed by the red signal in accordance
with sub-paragraph (a) would be likely to hinder the use of that vehicle
for the purpose for which it is being used, then sub-paragraph (a) shall
not apply to the vehicle, and the red signal shall convey the
prohibition that that vehicle shall not proceed beyond the stop line in
a manner or at a time likely to endanger any person or to cause the
driver of any vehicle proceeding in accordance with the indications of
light signals operating in association with the signals displaying the
red signal to change its speed or course in order to avoid an accident;

(c) the red-with-amber signal shall, subject in a case where it is
displayed at the same time as the green arrow signal to sub-paragraph
(f), denote an impending change to green or a green arrow in the
indication given by the signals but shall convey the same prohibition as
the red signal;

(d) the green signal shall indicate that vehicular traffic may proceed
beyond the stop line and proceed straight on or to the left or to the
right;

(e) the amber signal shall, when shown alone, convey the same
prohibition as the red signal, except that, as respects any vehicle
which is so close to the stop line that it cannot safely be stopped
without proceeding beyond the stop line, it shall convey the same
indication as the green signal or green arrow signal which was shown
immediately before it;

(f) save as provided in sub-paragraphs (g) and (h), the green arrow
signal shall indicate that vehicular traffic may, notwithstanding any
other indication given by the signals, proceed beyond the stop line only
in the direction indicated by the arrow for the purpose of proceeding in
that direction through the junction controlled by those signals;

(g) where more than one green arrow is affixed to light signals in
accordance with regulation 34(1)(b), vehicular traffic, notwithstanding
any other indication given by the signals, may proceed beyond the stop
line only in the direction indicated by any one of the green arrows for
the purpose of proceeding in that direction through the junction
controlled by those signals; and

(h) where the green arrow signal is displayed at the same time as the
green signal, vehicular traffic may proceed in the direction indicated
by the green arrow in accordance with sub-paragraph (g) or in any other
direction in accordance with sub-paragraph (d).

(2) Vehicular traffic proceeding beyond a stop line in accordance with
paragraph (1) shall proceed with due regard to the safety of other road
users and subject to any direction given by a constable in uniform or a
traffic warden or to any other applicable prohibition or restriction.

(3) In this regulation the expressions "vehicle" and "vehicular traffic"
do not include tramcars.
====

Note that there is *nothing* about the relative arrangement of the lamps
that aren't lit.

Summarising:
* Green arrows authorise movement in the indicated direction(s), whether
or not a red light is show.
* Green lights authorise movement in all directions.
* Green light plus green arrows indicate both.

Separately from this, my understanding of the other rules for lights is:
* A green arrow may only be extinguished when:
- an amber light comes on, or
- red+amber lights change to green light
on the relevant signal.
* Green light plus green arrow means that traffic turning in the
direction of the arrow does *not* need to worry about conflicting
movements.

Other regulations do talk about the arrangement of lamps.

* If there is a green lamp, one or two arrows or tramcar signals may be
placed on one side but not both sides. Arrows on the left must be
upwards or leftwards; those on the right must be upwards or rightwards.
The first arrow or sole tramcar signal must be beside the green; the
second arrow goes above it. If there are two arrows, the one nearest to
pointing upwards must be at the top; a tramcar signal goes above the
arrow, not below.

R R R R R R R R
A A A A ^A A^ TA AT
G G TG GT G G G G

* If there is no green lamp, then its place must be taken by a green
arrow. Another arrow or a tramcar signal may be placed on its left or
right side (but not both); if there is another arrow, a tramcar signal
may be placed above it, next to the amber. If there are two arrows, they
must differ by at least 45 degrees; the left of the two must not point
right of vertical while the right one of the two must not point left of
vertical, and the order must be "natural".

R R R R R
A A A A TA and similar on the right
^ T ^ ^

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

On Tue, 8 Jun 2004 at 21:31:43, Robin May
wrote:

I can think of one traffic light where a green light means you can go
forward and turn right if no traffic is coming from the opposite
direction, but a green light *and* green arrow mean that there is a red
light for traffic coming the opposite direction so you can turn right
without needing to worry about oncoming traffic.

Indeed, I think there's one on Clapham Common North Side, isn't there?
--
Annabel Smyth
http://www.amsmyth.demon.co.uk/index.html
Website updated 6 June 2004

"Richard M Willis" wrote in message
om...

Do the USAns have filter arrows, or is it a Europe-specific thing ?

Not usually, but they often have arrows above the lanes which are supposed
to go that way.

Aside: does anyone know why some traffic signals here show a
green filter arrow *AND* a solid green light simultaneoulsy,
given that the latter allows a superset of the filtered traffic
to "go". ?

The green arrow shows that it is safe to turn as the oncoming traffic has
been stopped by a red light.
--
Terry Harper, Web Co-ordinator, The Omnibus Society
75th Anniversary 2004, see http://www.omnibussoc.org/75th.htm
E-mail:
URL: http://www.terry.harper.btinternet.co.uk/