[sustran] Re: Updates on Delhi bus crisis

[Kerry Wood]

Dear Debi

Sorry, but I know very little about diesel/CNG systems: I will see what
I can find out on Monday.

My understanding is that the diesel engine still has a standard diesel
fuel system, presumably with a modified link between the accelerator
pedal and the injection pump.

It also has a CNG tank, or more likely tanks, and an injection system
into the engine's intake manifold.

When the engine is idling it runs entirely on diesel, but when under
power it runs on enough diesel to provide ignition, and the rest is CNG.
>From memory the overall result is that about two thirds of the energy
use is CNG. Obviously a special control system is needed, to keep CNG
and diesel in balance.



Unfortunately getting books is not easy for me either: sustainable
transport is not very profitable in New Zealand!

I do have a spare copy of the first edition of the Sustrans Manual
(1994), which I shall mail to you on Monday.

It is a useful document In New Zealand, but my guess is that in Mumbai
it will need revision to cover things like greater widths for large
numbers of cyclists, and some thought about motor cyclists. The Dutch
view seems to be that they are better in the motor traffic stream, but
physically keeping them out of cycle tracks is impractical (however,
cars can be kept out by bollards spaced 1.5 m apart). In Mumbai, pedal
cycle numbers might be high enough to stop the motorcycles going too
fast, or you could try speed humps where needed.

Some information from the CROW manual might be helpful:

•    Minimum width of a cycle lane is 1.5 m, maximum width 2.5 m (any
wider and it gets used as a parking or traffic lane)

•    A cycle track (physically segregated from motor traffic, with a
separation strip) should have a capacity of about

    (((Width - 0.8 m) x 3300) + 1000) cycles per hour one way

    (that is my interpretation of the data in CROW, but remember that
the minimum practical width is 2.0 m for one way or 2.5 m for two way)

•    CROW give a speed hump design to slow motorcycles, but they suggest
it is only used at dangerous sites. The diagram is not very clear
(figure 7.5) but they use two humps, one immediately after the other.
Humps are 120 mm high with a 10% ramp each side and a flat top 0.5 m
long.

•    Minimum width for a combined bus/cycle lane is 4.2 m, or 6.2 m for
buses in one direction but cycles in both directions.


Hope that is helpful.


Kerry


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