Re: [MELB] Speed of metropolitan trains

["Roderick Smith" <rodsmith@werple.net.au>]

I have calculated a base case on a typical station spacing being 1500 m,
with trains allowed 65 km/h, and 20 sec stopping time.  Using the
specifications for Melbourne's double-deck set: 0.75 m/sec/sec
acceleration; 0.9 m/sec/sec service braking:

accelerate for 24 sec (216 m)
cruise for 61 sec (1104 m)
brake for 20 sec (180 m)
stop for 20 sec
The cycle takes 125 sec, giving an effective average of 43 km/h.

To interpret this: the 45 km journey from Melbourne to Belgrave (currently
allowed 73 m, stopping at all stations except East Richmond), would take 63
min, stopping at all stations.

Allowing a maximum speed of 80 km/h would reduce this to 58 min.
Allowing a maximum speed of 100 km/h would reduce this to 56 min.

Reducing the stopping time to 15 sec would give the three times: 60 min, 55
min, 54 min.

Improving the acceleration to 0.9 m/sec/sec (without reducing stopping
times) would give 63 min, 58 min, 52 min.

Improving acceleration and braking to 1.0 m/sec/sec (still ok for
standees), and retaining 20 sec stopping times would give  61 min, 57 min,
51 min.

Improving acceleration and braking, and reducing the stopping time to 15
sec, would give 58 min, 54 min, 49 min.

AFAIK the Paris metro relies on stopping times of 7 sec (10 sec?).  In days
gone by, this was achieved by sharpening the door edges so that nobody
would try to beat the doors: but they had little incentive to do so, as
there was another train only a couple of minutes later.  Melbourne still
has typical headways of 20 min (30 & 40 min at nights and weekends).

The Belgrave line actually has limits of 55 km/h to Burnley, then 65 km/h
to beyond Box Hill (80 is allowwed only on the centre line); then a fair
amount of 80 in the outer areas.  This would require a more-detailed
analyisis than the quickie above.

The gap between theoretical and actual to Belgrave represents the delays
caused by Melbourne's kinks and restrictive points and curves, plus the
allowance for wheelchairs at stations, delays because of failures,
level-crossing accidents, crews not arriving...

-- 
Regards
Roderick Smith
Rail News Victoria Editor