It is one of the classic problems of urban transport that once
a unit (Bus, train, tram, anything) gets behind, it gets further
behind. Since it is behind, more passengers arrive at the stops, they
take more time to get onto the unit, and the unit gets heavier, so is
slower, and the problem spirals out of control. Buses can sometimes
overtake, but too often the following driver enjoys having the stops
cleared for him and doesn't want to take on the work of clearing the
stops for the driver in front, so he doesn't overtake. With any other
kind of transport, overtaking is actually impossible, a situation
which sometimes led to the yellow Newcastle trolley-buses being called
"bunches of bananas". But bunching is notorious with London diesel
buses. The only other way of stopping this problem is for the unit IN
FRONT to be slowed down. This is done on the Paris metro.

Some years ago there was a much publicised programme of
fitting Dublin buses with radios "for control", to give the advantages
of a metro using fairly cheap technology. Thinking about it now, I
think that solving this problem was one of the objectives.

Am I right in this guess? What happened to this programme? It
seemed to be one of those things whose start was trumpeted loudly and
was never heard of again.

Michael Bell
--

In message , Michael Bell
writes
e only other way of stopping this problem is for the unit IN FRONT to
be slowed down. This is done on the Paris metro.

So the already late bus is slowed down to allow the on time bus to
overtake and take all the passengers?
--
CJG

CJG wrote:
In message , Michael Bell
writes
e only other way of stopping this problem is for the unit IN FRONT to
be slowed down. This is done on the Paris metro.

So the already late bus is slowed down to allow the on time bus to
overtake and take all the passengers?

No, you've misunderstood. The idea is to slow down the bus IN FRONT of the
late one in order to even up the intervals.
--
Richard J.
(to e-mail me, swap uk and yon in address)

On Mon, 1 Sep 2003 18:53:55 +0100, Michael Bell
wrote:

I can't see how you read it that way. We have a bus that is getting
late. So the bus IN FRONT of it is slowed down.

Making it, umm, late as well. Not sure I like that one.

Better is to make sure the timetable works in the first place. Except
when special events are taking place, or major roadworks, or whatever
(in which case extras need to be added to the service), heavy loading
is inherently predictable. If this is happening all the time, the
timetable is faulty.

Neil

--
Neil Williams
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Try my first name at the above domain instead if you want to e-mail me.

On Mon, 01 Sep 2003 20:52:25 GMT, "Richard J."
wrote:

Ever heard of traffic jams?

Yes, which are generally either...
1) Caused by a "special event", roadworks etc, and so can be predicted
and planned for if they are known about.
2) Predictable as they happen every day, in the same place, at the
same time.
3) Caused by an unpredictable event such as an accident (which
admittedly I missed out...).

In cases (1) and (2), fixing the timetable (either temporarily by
adding extras/reliefs or permanently) is the answer. IMO, bunching
caused by option (2) is the most common.

In case (3), it depends on the disruption and the alternatives.
Diverting buses may be sensible, as may (if any are available)
dropping in an extra bus running to time further down the route. I'm
not sure that delaying passengers who have passed the obstruction and
would not otherwise be delayed is the answer.

Bunching can, of course, also be caused by demand - if there is
particularly heavy demand for a given journey, it may be sensible to
operate two buses which can be "pre-bunched" and leapfrog each other
at each stop in order to share passengers. Off-bus ticketing also
helps, as the delay at each stop is smaller.

The idea of having radio communication between drivers is an
interesting one - it'd be very useful for a driver to be able to ask a
driver in front to move up a bit so he could get out, or if full (and
there's another bus directly behind as a relief, for example) to
request that bus to stop instead.

Neil

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On Mon, 01 Sep 2003 21:39:02 GMT, "Richard J."
wrote:

The most elementary study of traffic jams will show that tiny events (such
as a car parking for 10 minutes in a bus lane, or a side road temporarily
blocked by a large truck reversing into a narrow entrance) can have
unforeseen effects on traffic flow. The idea that it is all predictable
apart from the occasional accident is not realistic. If it's all so simple,
why have we had bunching problems for the last 50+ years?

Because...

1) Off-bus ticketing, the majority holding passes, boarding at the
back while people pay at the front etc. are more or less unknown in
this country - and are only just appearing in London. This is what
causes the extensive delays at stops, day in, day out, which causes
day-to-day bunching - and is in particular what causes bunching to get
so bad after what seems to be a minor delay to start with.

2) Privatised bus companies are in it for the money, and produce
unrealistic, too-tight timetables which will always lead to bunching.
Admittedly this has only been the case since the mid-1980s, but it is
very relevant.

You'll not get 100% of bunching by addressing those two issues, but it
will certainly help. You're right in that not all traffic congestion
can be foreseen - but, especially on the approach to cities in the
morning peak - so much of it is, and is not adequately planned for.

I think it's not so much a case that solving bunching (in many, but
admittedly not all, cases) is an impossible task. It just costs
money, which is something that is scarce in the PT world - certainly
the bus world - with the possible exception of London where these (and
other) issues *are* being addressed to an extent.

The unforeseen bunching can be helped, as well - you'll likely not get
the offending bus back on time, but if you've got enough spare
vehicles in the correct places and a decent overall control setup
(again, these cost), an extra could be dropped in so that bus could
run more or less non-stop to its destination without delaying those in
front as was being suggested.

Neil

--
Neil Williams
is a valid email address, but is sent to /dev/null.
Try my first name at the above domain instead if you want to e-mail me.

On Mon, 01 Sep 2003 22:01:59 GMT, (Neil
Williams) wrote:
Because...

1) Off-bus ticketing, the majority holding passes, boarding at the
back while people pay at the front etc. are more or less unknown in
this country - and are only just appearing in London. This is what
causes the extensive delays at stops, day in, day out, which causes
day-to-day bunching - and is in particular what causes bunching to get
so bad after what seems to be a minor delay to start with.

2) Privatised bus companies are in it for the money, and produce
unrealistic, too-tight timetables which will always lead to bunching.
Admittedly this has only been the case since the mid-1980s, but it is
very relevant.

There is extensive off-bus ticketing in Dublin, using validators near
(a bit too near perhaps) the front doors. On the second point, Dublin
Bus is not private!

Dublin does, however, have very bad traffic a lot of the time, and I
don't think we can expect that to have little effect on bus
timetables, whatever is done about timetable planning or dwell time at
the stops.

A recent article in "Buses" talks of how mobile radio is used in
Dublin, and as well as for regulation of a particular route it is also
apparently used to assign drivers from a special pool to any route as
and when necessary, which is more or less what you suggest below...

The unforeseen bunching can be helped, as well - you'll likely not get
the offending bus back on time, but if you've got enough spare
vehicles in the correct places and a decent overall control setup
(again, these cost), an extra could be dropped in so that bus could
run more or less non-stop to its destination without delaying those in
front as was being suggested.

There are also a number of express routes that are IIRC peak-hours
only, this must make controlling it all interesting to say the least.

I'm sure radio is also useful for security.

I'm not sure how much of their radio use can be considered an
experiment any more. You'd expect any major - and in this case
capital - city to be able to communicate with its buses, wouldn't you?

Richard.

"Richard J." wrote:

CJG wrote:
In message , Michael Bell
writes
e only other way of stopping this problem is for the unit IN FRONT to
be slowed down. This is done on the Paris metro.

So the already late bus is slowed down to allow the on time bus to
overtake and take all the passengers?

No, you've misunderstood. The idea is to slow down the bus IN FRONT of the
late one in order to even up the intervals.

And then they get hoots of derision from the passengers on the
deliberately-delayed service when they tell them they are "regulating
the service" (as heard on the Jubilee Line at Bridge).

--
James Farrar |
London SE 13 |

On Tue, 02 Sep 2003 20:12:32 +0100, James Farrar
wrote:

And then they get hoots of derision from the passengers on the
deliberately-delayed service when they tell them they are "regulating
the service" (as heard on the Jubilee Line at Bridge).

Quite. There are arguments for doing this on a railway, where there
are limited opportunities to send an additional vehicle via an
unaffected route to take up the delayed service's place, for example.
With buses, however, there is much more flexibility (provided the
money is there) to resolve the situation without inconveniencing other
passengers who are not already delayed.

Incidentally, I do agree with the idea of bus drivers and control
being in radio contact - this can, of course, be used for other forms
of service regulation, reporting problems, monitoring delays, asking
for relief vehicles to be sent and even (if set up with on-bus PA) to
allow control to advise passengers of problems elsewhere on the system
(a word which sadly doesn't usually apply to bus operations in the
UK). Just not the idea of delaying buses to fill the gap...

Neil

--
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Try my first name at the above domain instead if you want to e-mail me.