"Rod Speed" wrote in message
...
Then what does "jumping" mean in this context,

Moving forward before the light actually goes green.

Before they go green, either yellow or amber is shonw

Wrong, as always.

No, he's right: immediately before a green light there is a red+amber phase
for most lights, and before that is a red phase. Pedestrian lights are an
exception: I *think* the red light goes out, displaying no lights for a
brief interval, then the amber light alone appears as the beginning of the
flashing amber phase that precedes green.

which indicated proceed with caution which you
are leagly able to do BEFORE the light goes green

Wrong, as always.

Yes, as I understand the Highway Code, *any* light or light combination
other than red means STOP or DO NOT START. The reason that the amber phase
(stop if possible and not too close to stop in the remaining distance) is
present is to give ample warning that the red light is about to appear, so
that red can mean "stop - with no excuses about being too close to stop in
time because you've been warned".

I sometimes stop a couple of yards short of the stop line, and when the
lights turn red+amber, I start moving, judging it so I will reach the line
just as the lights turn green. That's legal: and causes great consternation
if there is a fast sports car alongside, where the lights have two lanes,
because a low-powered car, already moving at 5 mph as it passes the stop
line, can out-accelerate a powerful car that is starting from rest at the
line.



How about this situation https://goo.gl/maps/H6F3ndyoji62 which I
encountered the other day: a side road which is right next to traffic lights
(to enforce single-alternate traffic on a narrow [1] bridge). I wanted to
turn right. The only view I had of lights was obliquely, looking at the
light intended for traffic coming from my left. I stopped, checked the
lights and for oncoming traffic in either direction. Since the lights were
green and there was no traffic coming from the left, I pulled out. After I'd
started moving, the lights went amber.

Should I have continued, passing the lights at amber although I could stop
in time because I was moving slowly; or should I have stopped, blocking both
sides of the road because there is insufficient room to straighten the car?

I chose the latter, turning slightly left before hard right, mounting the
kerb slightly and stopping slightly beyond the stop line - so as to
straighten as much as possible in the space available, but still partially
blocking the exit from the bridge. I'd already assessed that the situation
might arise, when I originally turned right into the road earlier on, and
had thought "there is a risk that the lights may change after I've started
moving". I'd already decided that if it happened, I'd try to reverse back
into the side road; in the event, I couldn't do that because there was a car
behind me.

The lights are too close to the side road [2] and have not been designed
with this eventuality in mind: to allow a car that has started to pull out
from the side road when it sees a green light, room to straighten and stop
at the line if the lights change after the car has committed to pulling out.
If they were moved a car-length closer to the bridge, the problem would not
have arisen. https://goo.gl/maps/Ff4Zig9xjWr shows that there is a looong
gap between the junction (St Margaret's Road) and the start of the bridge
parapet, with another driveway in between. https://goo.gl/maps/DUy63rRfQyy
shows that the stop line is roughly level with the right-hand kerb on the
side road.


[1] The bridge looks to have been built to be wide enough for two-way
traffic but subsequently the pavement has been widened and the road
narrowed, presumably to give pedestrians and push-chair/wheelchair users
more room so cars do not pass them so closely.

[2] Though the main road, Stockwell Road, narrows immediately after the side
turning, so moving the lights any closer to the bridge would narrow the exit
for wide vehicles.