[TCUG] Re: 'Wacky ideas'
- From: Saffer Howard <Howard.Saffer@xxxxxxxxxxxxxxxx>
- To: "'tcug@xxxxxxxxxxxxx'" <tcug@xxxxxxxxxxxxx>
- Date: Thu, 10 Jun 2004 16:54:48 +0100
One idea that I like - again from somewhere in Europe (Spain maybe? - I can't
remember)- in relation to higher speed roads (probably the equivalent of 40 and
50 mph speed limits) is to 'slow-flash' the green signal (two or three
times)immediately before the leaving amber - only on a max change. This really
assists with amber-zone decisions for approaches with good visibility over long
distances on a high speed approach (should be easy to implement too). From
observation, I suspect it could considerably improve road safety at this type
of site.
Howard Saffer
Traffic Signal Design Group
DEL - Development Services
Sheffield City Council
Tel: 0114 - 273 - 6154
Fax: 0114 - 273 - 6182
Mailto:howard.saffer@xxxxxxxxxxxxxxxx
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-----Original Message-----
From: mervyn.hallworth@xxxxxxxxxxxx
[mailto:mervyn.hallworth@xxxxxxxxxxxx]
Sent: 10 June 2004 15:01
To: tcug@xxxxxxxxxxxxx
Subject: [TCUG] Re: 'Wacky ideas'
Those of you at yesterday's Open Meeting will be aware that we have been
asked by the CSS Transport and Environment Committee to effectively come up
with a number of 'wacky ideas' which might (say) help to relieve congestion
in our towns & cities or make them safer/cheaper to run etc. This is based
on the fact that we are no longer building new roads so we need to make
better use of those we've already got. The hundreds of ideas (?) we come up
with will be sifted by TCUG Committee before passing a 'short' list on to
the Environment Committee later in the summer.
To start off this process, here is a 'not so wacky' idea (actually in use
in one part of UK - Northern Ireland):
'Magic ambers'
The 'early start' sequence at signalled junctions, to provide right turning
vehicles with priority, has some advantages over the (more widely used)
'early-cut-off' sequence. 'Early starts' can reduce confusion for
pedestrians (one direction of traffic does not suddenly stop leaving the
other still running - as with 'early cut-offs'), and it can handle more
right turners per cycle (since vehicles can not only turn right during the
'early start' stage, but also later during the intergreen following the
'two-way running' stage). In some cases (depending on junction spacing &
cycle time) it can also fit in better with UTC coordination.
But the 'early start' suffers from accident potential, due to uncertainty
for right turners on the change from 'early start' stage to 'two-way
running' stage. This safety problem has, in recent years, often been
relieved by the use of an 'indicative right turn arrow' during the 'early
start' stage, but despite this the technique is little used outside NW
England. The exception to this is Northern Ireland where (as I understand
it) they routinely add an extra AMBER signal specifically to address the
uncertainty issue - sited above the indicative green arrow and appearing
for 3 secs after the termination of the associated green arrow. The fact
that Northern Ireland have written such use of an amber (ie without an
associated red) into their own version of TSR&GD, would appear to be an
endorsement for the use of this technique - indeed they commonly refer to
the signal as 'Magic Amber'.
Arguably the rest of the UK should have access to this facility and
furthermore (at some risk of delaying its use the odd decade!) it could
possibly be enhanced by the use of 'amber arrows' instead of 'full ambers'.
So, for the avoidance of doubt, the 'Magic Amber' sequence I am suggesting
could be selectively trialled (outside NI) is:
RED (direction 1), RED (direction 2)
RED (direction 1), RED/AMBER (direction 2 - using the
'normal' amber)
RED (direction 1), FULL GREEN + RT ARROW (direction 2)
RED (direction 1), FULL GREEN + RT AMBER ARROW (direction
2 - using the 'magic' amber')
RED (direction 1), FULL GREEN (direction 2)
RED/AMBER (direction 1), FULL GREEN (direction 2)
FULL GREEN (direction 1), FULL GREEN (direction 2)
AMBER (direction 1), AMBER (direction 2 - using the 'normal'
amber)
But I'm sure y'all can come up with much 'wackier' ideas than this!
Mervyn
Leeds
0113 2476750
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