TT #176: The power of frequency

Add one or two extra trips to a country train or coach service that has only a few trips per day. It doesn't sound very exciting does it? Especially for city people who take more frequent service for granted. 

However it is actually very significant. It is not often enough remarked that the number of travel options increases exponentially with frequency. Here's some examples based on hypothetical regional rail timetables. 

2 trips / day trip one end

The diagram below is a train graph as often used by schedulers. 24 hour time is across the bottom (x-axis) with location being the y axis. B is a hypothetical regional city while A is the capital. Each line is a scheduled train service going in the direction shown by its arrow. Each trip takes about 3 hours. If you were able to make the train faster the line slopes would be steeper. Rail planners often refer to trains from B to A as 'up' and those from A to B as 'down'. 

This timetable is operationally elegant and quite efficient. Just one train does all trips. It's running about 75% of the time, with the 3 hour trip followed by 1 hour dwell time. The service is self-contained so any problems are isolated to it. There are also no crossing paths so the whole line can be single track the whole way. That reduces construction and maintenance costs, though there is less flexibility if a train needs to be terminated mid-way.    

Some people might be content to leave things there. This is not good enough. The timetable might be operationally efficient but is still poor if it doesn't meet community needs, eg allow convenient day trips.  

The above timetable works for that purpose for someone living in B wishing to spend a day in the capital A. Provided they get up early enough. In theory they could spend just an hour in A but this is unlikely given the length of the trip. Hence only one of the two scheduled return trips is useful. The same can be said for the afternoon trip to A since the choice is either stay an hour or stay overnight. Consequently for day trips from B to A only two out of four trips in the timetable are really useful. Also those in B wishing to use the train will almost certainly have to make their way to and from the station as local buses are unlikely to be still running at the time the first train departs and the last train arrives. 

How useful is the timetable for those in A travelling to B for the day? Unfortunately it's not. Whereas people in B can have a long day trip to A, those in A cannot in B. Their only option is a 1 hour visit in the middle of the day. Hence this timetable might be good for B residents but is poor for businesses in B who might otherwise benefit from their town being accessible for day trippers. 

2 trips / day trip both ends

You could fix the latter by adjusting the first down train so it departed A about 2 hours earlier, reaching B around midday. Departing the second up train 2 hours later completes the picture. Instead of an unusable 1 hour in B those from A can spend a much more useful 5 hours. If the last down train had catering then that could look after evening meal requirements. The trade-off with rescheduling these  trains is that those in B lose the ability to spend 1 hour in A but this is probably no big loss. 

The above timetable is more useful than the first but there are some operational issues. The crossing lines mean that there are two trains in the same place at the same time. Thus there needs to be dual tracks or, as a minimum, a passing loop. This needs to be about 30 minutes outside the capital for the above timetable to work. It sometimes needs explaining to country people that intelligently planned rail infrastructure near the city can benefit them. This would be a classic example with the timetable it enables being less capital-centric.

The other thing that would need to change is train scheduling - rather than a full use of one train this timetable relies on part-time use of two trains with interlining likely required. The midday 5 hour dwell at location B is another inefficiency, especially if B is a rail terminus with no other line to interline with. Accepting this means accepting poor asset utilisation and lower than possible patronage from the network.  

3 trips / more options

Shuffling earlier and later trips (and/or increasing speeds) can create a midday gap enough for a third trip each way. A graph is below. The 3 train each way Warrnambool weekend timetable is not unlike this pattern.  

Those extra midday trips make a huge difference for those living in B. A traveller from B now has the option of spending either a half or a full day in A. That half day can either be a late morning or late afternoon. The effect of adding two extra trips has meant that instead of one (long) full day option there are now three choices.   

The gains for those visiting B (eg Melburnians making day trips) is less. They retain their ability to make a day trip with a little more time. However they can't make useful half-day trips. This is because efficient train turnarounds at B mean that two out of their theoretical three options are impractically short for a day trip, although some multi-day travellers would still benefit.  

4 trips / even more options

Below shows a fourth trip added each way. The gaps between trains are uneven as I haven't shuffled the existing trips. To add it you may need extra trains and (certainly) at least an extra passing loop (about an hour from B) where trains cross if there is only one track. 

More trips means more options, and, in this case, multiplying options. Those in B no longer need to rise very early to see someone for lunch in A. They, plus those who took the first up train, get a new late afternoon departure with an arrival home just after the more respectable time of 8pm. This trip also benefits visitors from A who can finish work and reach their accommodation at a reasonable time. This could be a particular benefit on Fridays as it would permit almost a full weekend away.  

5 trips / filling the gaps

The above timetable still had some 6 hour gaps, making some trips inflexible. Just one extra trip each way cuts maximum intervals between trains to 3 hours. You are still very dependent on timetables but there is now a much greater chance of the train being suitable for a wide range of trips. 

This timetable adds a late morning trip from A to B, allowing an (almost) half-day stay. Although 2 hours is still a short time away for those making a 3 hour train trip, it still allows those in B to make a quick trip to A and be home by early afternoon. The second trip, which is formed by the last, enables those in B to make a dinner appointment in A. And if they are not too long (about 2 hours) they would be able to be home that evening on the last down train. 

6 trips / big gain for regional day trips

The above timetable is better than previous ones. Those in B visiting A have quite good flexibility of arrival and departure times. However it's still not so good for those visiting B. This is because you can't arrive much before midday, more leave after 6pm.

Adding one more trip each way transforms this. An early trip from A gives an option of an early morning arrival. And, possibly more popular, a late trip from B enables an evening meal there with an arrival at A at around midnight.  Neither may not be the most popular trip in the schedule but they add a much wider range of times that adds flexibility, again multiplying the trip combinations possible.    

Conclusion

I've discussed six hypothetical regional rail timetables. They show that adding trips multiplies the number of travel combinations and thus greatly increases the range of trips possible. In many cases higher frequency makes the network less Melbourne-centric as well-timed additional services can facilitate regional tourism. The best thing you can do to boost rail patronage is to do what you can to run the trains you have more frequently and thus harness the power of frequency.  

In the current state election campaign we've seen pledges for increased V/Line frequency from both major parties. These include promises from Labor for major weekend frequency upgrades and the Coalition for an extra morning service from Sale.  

Index to Timetable Tuesday items here