On Sep 7, 8:46*pm, Chris Tolley wrote:

Mizter T wrote:
A bus swerving to avoid a car would appear to be the genesis of the
accident. ... *if* (and that is a big if) the traffic signals had in
some way malfunctioned then things would become more interesting
given the interface between highway and tramway signalling.

I don't follow your reasoning. If the genesis of the accident is a bus
swerving to miss a car, then I can't see that the tram's signalling is
in any way implicated.


Sorry, I didn't make myself clear. In Croydon, as is the case
elsewhere with other tram systems, the highway traffic control signals
are linked in to the tram's signalling system so as to enable trams to
negotiate a variety of road junctions - this evidently requires a more
complex set of interlinking/interoperability (or even 'interlocking'
as it were) between the highway signals and the tram network's
signalling system. On top of that one can assume that at least some of
the highway signals in the area are co-ordinated with each other as
part of a traffic management setup (as I'm sure is the case in central
Croydon).

*If* the highway signals (indeed and the tram signals) had
malfunctioned then this could have caused or contributed towards the
car and/or bus (indeed and/or tram) being in the wrong place, hence
the relevance of this factor.

The reason I even mentioned signalling in the first place was the
'Croydon Today' article contained the suggestion, made by a witness,
that traffic lights might have been at fault - but one should note
that this is by no means verified information.

For the record, because local newspaper websites do get rejigged with
some regularity, here is a pertinent extract from the 'Croydon Today'
article:

quote
Road sweeper Martin Storm, 54, from Church Street, Croydon, who saw
the crash, said:
"The bus was coming up Park Street and swerved to avoid a car which
was coming down Wellesley Road.
"The bus driver swerved left to avoid the silver car. The bus driver
tried to avoid everything, but he couldn't avoid it.
"The car has got stuck between the tram stop and the bus and was
crushed.
The driver of the tram was really upset, but it wasn't their fault. I
was behind it all, there was blood everywhere."
He added: "The police told me the traffic lights had failed and were
all on green."
However while saying the traffic lights was one area which would be
looked at during the investigation, police today did not confirm they
had not been working.
/quote

Source:
http://www.thisiscroydontoday.co.uk/...l/article.html

Mizter T wrote:

On Sep 7, 8:46*pm, Chris Tolley wrote:

Mizter T wrote:
A bus swerving to avoid a car would appear to be the genesis of the
accident. ... *if* (and that is a big if) the traffic signals had in
some way malfunctioned then things would become more interesting
given the interface between highway and tramway signalling.

I don't follow your reasoning. If the genesis of the accident is a bus
swerving to miss a car, then I can't see that the tram's signalling is
in any way implicated.


Sorry, I didn't make myself clear. In Croydon, as is the case
elsewhere with other tram systems, the highway traffic control signals
are linked in to the tram's signalling system so as to enable trams to
negotiate a variety of road junctions - this evidently requires a more
complex set of interlinking/interoperability (or even 'interlocking'
as it were) between the highway signals and the tram network's
signalling system. On top of that one can assume that at least some of
the highway signals in the area are co-ordinated with each other as
part of a traffic management setup (as I'm sure is the case in central
Croydon).

*If* the highway signals (indeed and the tram signals) had
malfunctioned then this could have caused or contributed towards the
car and/or bus (indeed and/or tram) being in the wrong place, hence
the relevance of this factor.

Okay, that's clearer. Thanks.

--
http://gallery120232.fotopic.net/p9632771.html
(20 077 at Buxton, Jun 1985)

Graham Murray wrote:

Arthur Figgis writes:

Presumably the road and tram signals are interlinked in some way, to
avoid a tram being sent into the path of cars, or vice versa.

On the other hand, where a tram is running along a road, is there any
need for it to have separate signals? Would it not suffice for it to
have to obey the same red/amber/green traffic lights as other traffic?

One can imagine good reasons for there being a separate signal for the
tram, including the phasing of tram signals being different and,
especially in situations where there are multiple lanes of traffic, the
need to give a signal that applies to the tram but not to traffic.

--
http://gallery120232.fotopic.net/p9632899.html
(33 119 at Eastleigh, 15 May 1985)

On 8 Sep, 06:26, Graham Murray wrote:
On the other hand, where a tram is running along a road, is there any
need for it to have separate signals? Would it not suffice for it to
have to obey the same red/amber/green traffic lights as other traffic?

Croydon Tramlink doesn't have a signalling system. It's fairer to say
that the traffic light system includes lights targeted at tram
drivers.

U

On Sep 8, 7:43*am, Mr Thant
wrote:
On 8 Sep, 06:26, Graham Murray wrote:

On the other hand, where a tram is running along a road, is there any
need for it to have separate signals? Would it not suffice for it to
have to obey the same red/amber/green traffic lights as other traffic?

Croydon Tramlink doesn't have a signalling system. It's fairer to say
that the traffic light system includes lights targeted at tram
drivers.

As it might have for different lanes of traffic in any case,
presumably, given that trams have their own lanes.

"Mr Thant" wrote in message
...
On 8 Sep, 06:26, Graham Murray wrote:
On the other hand, where a tram is running along a road, is there any
need for it to have separate signals? Would it not suffice for it to
have to obey the same red/amber/green traffic lights as other traffic?

Croydon Tramlink doesn't have a signalling system. It's fairer to say
that the traffic light system includes lights targeted at tram
drivers.

U
Surely the white lights which show horizontal (stop), vertical (go) and
diagonal (junction) count as signals? The drivers certainly treat them like
signals!

MaxB

"Batman55" wrote

Surely the white lights which show horizontal (stop), vertical (go) and
diagonal (junction) count as signals? The drivers certainly treat them
like
signals!

Indeed they are. Tram drivers are not required to observe road
(red/amber/green) traffic lights, but there will be a white dot signal head
at the same location. These are also to be found at junctions, level
crossings, and at the section of interlaced track. Elsewhere the trams are
driven on sight.

Peter

Arthur Figgis wrote:
There was an accident involving a bus, a (reported to be parked) car, a
tram, and possibly a moving car, in George Street, Croydon this morning.
Unfortunately the pedestrian was killed, and the bus driver injured.

It seems to be a slightly out-of-the-ordinary accident - the tram and
bus have ended up quite a way from each other.

http://www.thisiscroydontoday.co.uk/...detail/article.

http://www.dailymail.co.uk/news/arti...e-Croydon.html


(people should avoid the Mail's pictures if they would be offended by
knowing it is tram 2534).

The bit that makes the least sense to me is the line, in both papers,
"sending the bus careering about 100m down the road". 100m is a long
way for a bus to travel apparently not under control.

Robin

On Sun, 07 Sep 2008 22:26:26 +0100 someone who may be Graham Murray
wrote this:-

On the other hand, where a tram is running along a road, is there any
need for it to have separate signals? Would it not suffice for it to
have to obey the same red/amber/green traffic lights as other traffic?

Yes, which is why separate signals are provided.

There are many reasons why tram drivers may be given separate
signals, for example if a tram is to start off before other traffic
at a junction a separate signal is needed. The "amber" period for a
tram is a few seconds longer than for motor traffic. It is also
considered less confusing for operators of other forms of traffic.

Having decided to provide separate signals for tram drivers the next
question was what form these signals would take. The two contenders
were tram stencils on coloured lights (just as there are bike (and
possibly bus [1]) stencils in places) or white lights. In essence
the white light system was chosen as there is less chance of
confusion with signals for other forms of traffic.

White light signals could be provided by standard traffic light
units with clear lenses and the appropriate stencil. However, the
"searchlight" unit was chosen as it is smaller than a three light
traffic light unit (being fitted to the top of a pedestrian crossing
pole is a lot neater than having a second traffic light unit beside
the one for other traffic) and can provide a greater variety of
indications.

Given the limitations of operating on the roads I think the system
would be hard to improve on.



[1] I have a very vague recollection of having seen bus stencils
somewhere in the UK. Bike stencils are provided in places though,
unlike some other places, there is no stencil on the red lens.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 8 Sep, 16:35, "Batman55" wrote:
Surely the white lights which show horizontal (stop), vertical (go) and
diagonal (junction) count as signals? The drivers certainly treat them like
signals!

I didn't say it didn't have signals, I said it didn't have a
signalling system. I'm assuming the lights at junctions are
freestanding installations of minimal complexity, and the tram lights
at road junctions are just traffic lights with unusual heads. There's
nothing more elaborate than that, as far as I know.

U