[sustran] Still more on Jakarta and other places

[Kerry Wood]

Hello everybody

Coming back to the last exchange but three,

Eric Bruun wrote:

> Of course we all like Curitiba-like approaches. Curitiba is progressive
> on almost every urban development issue. But what do cities do when
> it is not possible to get control of the streets? Nothing? Just stay
> with buses in mixed traffic?  Sometimes separte rights-of-way are the only
> realistic way to improve things.  Eric

And Curitiba has very wide streets.

Obviously there is no all-purpose solution - the answers will depend on what is
there now, topography, density, culture (no-go areas for public transport?),
climate and perhaps wealth above all. And what is sexy enough to justify a loan.

A range of fashionable and not-so fashionable options can be broadly graded, then
mixed-and-matched to put together an appropriate public transport system. In a
rough order of increasing cost and capacity they are:

1    Plain old buses (POB)
    Boring but effective. Vuchic found that US cities with light rail have more
passengers on the buses ALONE than cities without light rail. Can be slow and
unreliable if delayed by congestion.

2    POB + bus lanes
    More effective but still boring. May be barely more effective if the bus
lanes are in the places where they are easily fitted in, which are usually not
the places where they are most needed.

3    POB + bus lanes + priority + integration
    GPS positioning linked to traffic signals, plus timekeeping feedback to the
driver. Traffic signal priority may be barely perceptible or near-absolute  - the
higher the better. Zurich has achieved 95% within plus 30 to minus 90 seconds,
for both buses and trams, but I suspect it doesn't have to be quite that good.
    Integration of ticketing and timetables plus keeping to the timetable so that
the inevitable interchanges work well. Avoiding interchanges because people don't
like them is probably counter-productive.
    Priority may be practical even if a street is too narrow for exclusive public
transport space, by controlling traffic entry to the bottleneck at a rate low
enough to ensure reasonably free-flow conditions, and providing for public
transport to bypass the approach queue and go straight into the bottleneck.
Another approach is to just exclude other motorised traffic, as has been done for
Leidsestraat in Amsterdam (shopping street, width about 10 m, used by a single
track tramway with passing bays on the canal bridges. Commercial delivberies are
made before 10.00).
    Capacity may be an issue, for either the bus route or for other traffic
crossing it. Or both. If traffic signals work on a 90 second cycle and the route
is used by 60 buses an hour, that is one or two buses each way on each cycle.
More if there is bunching but bunching indicates bad timekeeping. With full
priority this may use as much cycle time as can be spared - especially if two
priority routes cross. If this is the case the route capacity is say 60 buses x
50 people = 3000 passengers/hour, or say 4000 pass/h for bendy buses.
    Some routes manage much more: Gardner (A study of high capacity busways in
developing cities, Proceedings of the Institution of Civil Engineers - Transport
- August 1992) quotes over 20 000 pass/h, but this needs a lot of priority at
junctions and a lot of width at stops. Route lengths quoted are 1.3 - 9.5 km, so
these are not whole systems.

4    Light rail
    A modern system is likely to have a high priority and to be mostly segregated
or semi-segregated, but at the basic level this is just option 3 with bigger
vehicles. Capacity say 40 trams/h carrying say 400 passengers each, or 16 000
pass/h. Capacity can be increased to perhaps 60 trams/hr with grade separation at
most or all junctions, and vehicle capacity can be increased to perhaps 600. The
limit here is as much vehicle length as how many people can squeeze in - the
vehicles cannot be longer than a central city city block.
    For poorer cities, there is the option of second-hand vehicles, or maybe new
vehicles built locally to an older design.
    Minimum capacity of the busiest section (set by costs) is around 2000-5000
pass/h, depending on the number of bells and whistles.
    Critics tend to see light rail as very expensive but a good busway is not a
lot cheaper. Light rail is sexier, but I suspect the real advantages are a bit
more subtle:
-    Bigger vehicles mean longer headways, so higher capacity than a busway can
be reached without interfering too much with cross traffic and without needing
very expensive grade separation.
-    Longer headways mean that a vehicle can obstruct the route at a stop, so
less width is needed than for a busway with the same capacity. The difference is
about one traffic lane. For a tight squeeze the tracks can be interlaced to make
a short section effectively single track. A 100 m length makes very little
difference to operations if the headway is more than 2-3 minutes.
-    The rails obviously have to be continuous, reducing the political pressure
to compromise (surely the buses can just join the traffic stream here...).
-    A completely predictable path means safer operation in pedestrian areas.
-    Smooth acceleration and braking,, and low acceleration forces when
cornering, mean that having passengers stand is much more acceptable than in a
bus. Passengers often stand when seats are available. This allows more space to
be given to standing passengers, which increases capacity and allows faster
boarding.

5    Everything else
Separate rights of way, in the sky, below ground, on an old railway, wherever.
Choose your technology (including the fancier forms of light rail) and squeeze it
in where you can. Sorry, no more cheap solutions.

Getting control of the streets is the key bit, but it doesn't have to be done all
at once, and it helps when you realise that traffic will adjust to capacity
reductions - at least within limits - as well as capacity increases. Average
commuting times in London have apparently been reasonably stable for six
centuries.

Where Jakarta fits on all this I have no idea. Obviously it is Option 5. I hope
it is a good solution for tthe local conditions.

--
Kerry Wood  MICE  MIPENZ  MCIT
Transport Consultant
1 McFarlane Street, Wellington 6001, New Zealand
Phone + 64  4  971 5549