[TCUG] Re: Red lamp monitoring.
- From: mervyn.hallworth@xxxxxxxxxxxx
- To: tcug@xxxxxxxxxxxxx
- Date: Thu, 28 Apr 2005 16:00:18 +0100
Sounds like this could occur on many VA junctions. Arguably TR2210 should
have made sure we get the 'ped phase min' time even though we don't get
the 'ped green'! In the absence of this, perhaps the answer is to always
specify a dummy phase running in the ped stage - in parallel with the
'real' ped phase - which would guarantee a minimum stage time?
Mervyn
Leeds 2476750
"Stewart, Ian (ENV)"
<Ian.Stewart@xxxxxxxx To:
"'tcug@xxxxxxxxxxxxx'" <tcug@xxxxxxxxxxxxx>
scc.gov.uk> cc:
Sent by: Subject: [TCUG] Red lamp
monitoring.
tcug-bounce@freelists
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28/04/2005 15:31
Please respond to
tcug
Hi everyone, OK so my mail system now works :)
I have recently been testing a new configuration for a T junction with
pedestrians and tactile facilities. On this site there is only one
pedestrian crossing facility and the side road traffic must turn away from
them, except for buses and cycles. Side road flow is very light. A single
red lamp failure increases the intergreens to the ped stage by 2 seconds.
The sequence then is:
Press push button, lose vehicle green, intergreen 7s, additional intergreen
2s, green man 7s, intergreen 9s (includes 3s blackout), gain vehicle green.
Notice that the traffic was stopped for 25 seconds.
On a second red lamp failure on the same approach (the main road runs
nearly
all the time), the following sequence occurs:
Press push button, lose vehicle green, 3 seconds amber, red failures
detected, inhibit peds, normal intergreen 7s, additional intergreen 2s,
gain
vehicle green. Anyone waiting to cross will not get the green man and the
'wait' will remain lit.
Sight impaired people may not attempt to cross. Sighted people who use the
crossing regularly will ignore the red man and simply step off the kerb
when
the traffic stops, and then only have 9 seconds to safely clear the
crossing. Of course, I accept that this only occurs on the first ped
demand
after the second red failure and subsequent demands will have no effect.
The main road approaches each way have only the 2 red lamps, so a double
failure makes the site appear 'all out' until the amber and then green come
on again. I have requested a demand to be entered for the side road when
two red lamp fails are detected, which will at least give the pedestrians
more time in this rare event, and it is unlikely that this will produce a
conflict, due to the turning restrictions. However, this must be a very
common situation, with any manufacturer's equipment, and not only at T
junctions. At any site with a 'ped' stage (i.e. no parallel phases) the
controller can revert straight back to the conflicting green when the
second
red failure is first detected.
This is the second junction where I felt it necessary to make special
provision for this situation. Have any of you ever considered this to be a
problem, or made special arrangements to combat it?
Regards to all,
Ian
--
Ian M. Stewart
Senior Engineer
Traffic Signals
Highway Consultancy
Environment Directorate
Lancashire County Council
telephone: 01772 533736
mobile: 07831 097495
mailto: ian.stewart@xxxxxxxxxxxxxxxxxx
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