Saturday, October 10, 2009

800 minutes extra per year

A suburban bus stop whose relocation will save regular passengers up to 800 minutes per year commenced full service this morning. The stop, pictured below, cuts the number of road crossings required from the highway and shopping strip from four to one. Access time has been reduced from about four minutes to two minutes. Transfers from station platforms are also easier and are achieveable in just a few seconds from Platform 2.


The videos below show access to the 888/889 bus stop at Chelsea in 2008:

Part 1

Part 2

(Two parts were needed for this video as access took such a long time).


The video below shows how it is as of October 10, 2009 when the stop was relocated nearer the station:

(Quicker access meant it could be filmed on one short video only.)

Saving access time...

The travel time saving quoted in the title is worth a further look. 800 minutes is over 13 hours per year. In other words well over one working day.

It applies for a walk-on passenger using the bus twice daily for 200 days of the year and holds for people going to or from destinations on Nepean Highway.

It's a bit different when transferring between train and bus. This is because a faster access time does not save end to end time if it means is waiting 3 minutes instead of 5 minutes for a connection. However there would be times when the faster access time means a bus or train that would previously have been missed can be boarded.

The potential time lost due to a missed connection is a function of service frequency. For the 888/889 intervals between departures vary between 10 and 40 minutes. The train runs more frequently, but intervals can still be 30 minutes during early mornings, evenings and Sundays.

Hence any time the improved access allows an otherwise missed connection to be made can save the passenger up to 40 minutes waiting. That is the 'best/worst' scenario and savings would usually be less. If considered along with these cases where faster access does not speed end to end time the average is likely to tend towards an 800 minute yearly average, especially given more or less random waiting times.

...and better reliability

Does the relocated bus stop also help overall service reliability, as measured by variability in end-to-end travel times? Yes it does.

Train-only passengers complain if their train is 10 minutes late and thus their arrival is delayed by that much. While this does affect many, they get off lightly compared to those who need to change to a bus. A late train may result in a missed bus and a wait of 30 or even 60 minutes until the next one.

A missed bus connection can increase end-to-end travel time by up to 50%. Anyone would agree that such variability, even if it happens once or twice a week, would be a disincentive to use public transport, or at least local buses. Afternoon peak trips to outer suburbs are most affected due to the snowballing of train delays and infrequent buses home.

A 2 minute access saving helps by making some previously dicey transfers more reliable. Instead of a 5 minute late train being enough to cause a lost connection, the train can now be up to 7 minutes late and the connection can still be made. For people making this particular connection the gain from relocating the stop is not so much reduced travel time but increased reliability.

Sensible stop location is one piece of the puzzle that makes or breaks an integrated transport network. The relocation described here will strengthen the network by reducing travel times and improving overall reliability.

No comments: