Monday, April 28, 2008

Why fast interchange matters

a response to a Railpage discussion about Box Hill and the importance of minimising bus-train interchange time

There's worse interchanges than Box Hill, but best practice is that train to bus interchange should be maybe 30 - 60 seconds via just one ramp, steps or escalators (eg Werribee, Boronia or newer Perth suburban stations).

And it should not be possible to exit any suburban railway station without almost bumping into a bus timetable or information - something that is denied to Box Hill passengers.

Every minute longer in bus-train access times lengthens bus standing times by 2 minutes, assuming a co-ordinated pulse timetable system. This reduces the capacity of bus interchange and is poor efficiency. Where stations are midway along a bus route (and not at the end like Box Hill) long bus dwell times can also increase journey time for through passengers.

Two 'perfect connection' examples, both assuming a 4 minute buffer to allow for late trains/buses.

* 1 minute station - bus access time (ie good design)

Bus arrives: 9:55am
Access time: 1 min
Wait time: 4 min
Train Arrives/Departs 10:00am
Access time: 1 min
Wait time: 4 min
Bus departs 10:05am

(min bus dwell time 10 min)

* 3 minute station - bus access time (ie poor design)

Bus arrives: 9:53am
Access time: 3 min
Wait time: 4 min
Train Arrives/Departs 10:00am
Access time: 3 min
Wait time: 4 min
Bus departs 10:07am

(min bus dwell time 14 min)

The general concept is better explained in the diagram below:

Time is money. Multiply that extra 4 minutes by the number of bus movements per day, and then per year. It's big bikkies! Or try to economise by skimping on connections, but since that may add 30 minutes to passenger travel times it's a false economy as they'll drive instead.

In short, each second counts, and no effort should be spared in improving interchange, whether the delays be caused by poor initial design (Box Hill), a botched redevelopment (Melbourne Central) or placing car ahead of pedestrian access (most places - Caulfield example below).

1 comment:

Anonymous said...

Your caulfield example is mainly affected by Coles and their carpark. Poor urban planning.

As I posted on my own blog, I'm less sceptical about outer suburban hypermarkets but more sceptical about inner suburban small supermarkets and the damage they do to streetscapes.

Outer suburban hypermarkets fill a need which PT would always struggle to fulfill, the key urban planning decision is to get the inner suburbs right.

My ideal would have us going back to the 'showroom' idea for heavy goods, with quick and cheap (or free) delivery without the strings attached. This unfortunately requires Australia to go down the route used overseas, of having lots of cheap labour available.

For day to day goods PT can compete, but other cultural adjustments are necessary. For example, you don't see people in HK lugging giant tins of food in 'bulk' because people don't do 'bulk'. And in Japan, quality trumps quantity, a problem in Australia.

And women go to the clothes shops and buy ONE dress, and carry it home in an elegant, expensive carry bag. No trips to Target or KMart to buy several bags worth of stuff in garbage plastic bags.

In Australia, quantity trumps quality. More cultural adjustment needed.