Interesting Thread about Travel Time Calculations

[Jonno]

https://twitter.com/llib7/status/1634661291767001089?

Metro right down your alley!! Assumptions always seem to be flawed/car-biased. Like the 15min transfer penalty. Only exists if you need to wait 15min to transfer!

[#Metro]

Thanks Jonno. Unfortunately, this tweet isn't a robust argument IMHO for a number of reasons.

The tweet uses the word 'best'. This is not an observable.

Total in-vehicle time or door-to-door journey is more precise.

In a neutral and even-handed evaluation, both PT and cars are just boxes on wheels. The line capacities for both can be determined the same way.

The total raw door-to-door journey time for PT is access time + wait time + in-vehicle time

If we add more and more service, the wait time shrinks to zero. At this point PT journey time is just access time + in vehicle time + 0

In other words, a car is just an express mini-bus with no intermediate stops and a pickup at your door.

For this reason Car door-to-door journey time < PT journey time generally*.

The longer journey time from PT is a result of (a) walking to the stop, and (b) the service making stops. Add extra if the frequency is low.

* During peak hour, the two modes tend to be brought into balance and equalise as all attempts to find faster routes are exhausted.

Transfer Penalties

In terms of transfer penalties, there has been a focus on walk distance, comfort, and time. This has led to large interchanges being designed at high cost.

However, the transfer penalty arises from passengers changing their travel behaviour to incorporate the possibility of missing the connecting service.

If you have a set appointment time at X there could be a service that connects you to that just in time. But if you miss the connection you might wait another 30 minutes for the next service. You would change your behaviour to catch an earlier connecting service that gave you some buffer time.

This residual buffer time is the transfer penalty. It is the amount of additional time one is willing to spend to reduce the risk of a missed connection.

On low frequency services (30 min, 1 hour bus routes, e.g. Ipswich) this transfer penalty would be expected to be quite significant.

On high frequency services such as CityGliders etc, the impact is minimal. Therefore, it is reasonable to say that the transfer penalty reduces when both connecting services are frequent.

This is how the Toronto system in Canada works. Both buses and trains are frequent and so if you miss one it is not a huge issue.

Rapid Transport

Now what does this mean for rapid transport? It means that we should be making bus and train service (a) frequent and (b) high speed to make up for access time and waiting time. This is how you make PT competitive.

This is why in low density situations, we should design PT like this:

(Credit: Ozbob)

[verbatim9]

Yep, overall travel times will not be improved when travelling across the city, unless we have improved east west links. A prime example is extending the busway to Indooroopilly from UQ. This will cut travel time to and from the East and South from the West, thus, making public transport more attractive, inevitably increasing ridership.