Nuances of public transport services

STREETLIFE - Nigel Paul Villarete (The Freeman) - April 16, 2019 - 12:00am

(Part 2 - Capacity versus frequency)

In last week’s write-up, we talked about speed versus distance. This was referring to the choice of transport mode as to speed and the effect on the distance between their stations or stops --the faster the vehicle, the farther away the stops. A high-capacity system will result in too great a distance between stops that you will need lower-capacity systems to get you to your final destinations. You can’t install a shinkansen (bullet train) system, running at 200 kph as an urban commuter line.

The next comparison that really needs discussion is what would be the right choice between capacity and frequency. Many people think that the bigger and faster the system, the better. Not necessarily. The governing factor is that of demand --you don’t put something up if there is no demand. We build the right capacity to meet the demand, today and in the future. And we need to consider the frequency of service --how long do you wait to get a ride.

Suppose we want to have a better system between Town A to City B, and the present transport system involves mini-buses at 50-pax capacity departing every 30 minutes, and this effectively serves the present demand. What do we do if the demand will increase by 50% in five year’s time? 1.) We can change to 75-pax capacity buses but running still at 30-minutes interval; 2.) We can maintain the 50-pax capacity buses but departing every 20 minutes; or 3.) We replace them with a high-capacity train system.

Changing modes to railway introduces more permutations as to capacity, speed, and frequency. A train usually has three cars or couches, up to 10 for high-capacity subway systems, with each car having 90-130 passengers. In the above case, if we use the smallest capacity --a three-car train with 90-pax capacity, it will have to depart every 1 hour and 48 minutes! If we design something like MRT-3 with a 395-pax/train capacity, we have a service which leaves every two hours and 36 minutes! I doubt if people would be happy with that kind of service. If you put a subway, it’s every seven hours!

That is, of course, a number-crunching exercise which will have countless deviations in the real world. But the principles do not change. For the same demand, bigger capacities will mean less frequency, and longer waiting periods in between, and vice-versa. In far-away hinterlands, this may mean having transport services only once or twice a day. In the urban setting, those who have been to Tokyo, Hong Kong, and Singapore know you can readily get a train or bus ride every two to five minutes. How is our waiting time in Cebu nowadays, both in the city and the province?

So, the next time you hear people proclaiming they want an LRT from Santander towards Cebu City we should really take it with a grain of salt and let them show first what frequency and level of service they are talking about. (To be continued)

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