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:
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