I was reading through an old post on Peter Parker’s excellent blog about service frequency and its capacity to change travel behaviour; and it got me thinking about the marginal modal share return to increases in service provision. Here, quality is fairly broadly defined – I’m basically looking at a combination of frequency, ease of use, comfort, etc. Working out how patronage and modal share respond to investment in better quality public transport is an important factor in determining the optimal level (and nature) of the investment and the consequent service standard provided.
Current government policy is to make small, incremental improvements to public transport and hope that more people use it, both in actual trips made and as a proportion of total trips (modal share). This was a big part of Melbourne 2030 – government policy was for 20% of motorised trips to be taken by public transport by 2020, basically a doubling of its modal share. Now given that total trips are increasing – largely because the population is growing and employment is increasing – we will expect to see public transport patronage to increase even when it’s treading water in modal share.
So why did the government set such an ambitious target backed up by only moderate levels of investment. There are two explanations that immediately come to mind: firstly, that they were never serious about 20% by 2020 (probably the truth); secondly, that their expectations of marginal returns to investment with respect to modal share were that it was more or less constant. This would see every extra dollar spent on improving the quality of public transport improving modal share by the same amount every time. This is represented graphically below:
So has this happened? Whilst patronage on Melbourne’s public transport – and especially the trains – has been increasing substantially, the modal share for public transport has been going nowhere. Basically, the investment hasn’t done much to improve modal share.
An alternative Explanation?
Clearly, the state government’s story doesn’t explain what’s driving transport habits in Melbourne (pun intended). I’d propose an alternative explanation – modal share isn’t going anywhere because public transport ultimately has to compete with the car. Even though there’s been investment in public transport, and an argument could be made that the quality has improved slightly over the past decade, modal share isn’t going anywhere because public transport simply isn’t as convenient as the car for many trips. For modal share to increase substantially, public transport has reach the point where it is a better quality service than a car. This is the tipping point I alluded to in the title. This is expressed graphically below:
So, what are the implications if we accept this idea? Well, basically it means that public transport investment needs to be targeted to meet the needs of drivers rather than looking at public transport in a vacuum. An empirical example would be the Metropolitan Bus Upgrade Program, where lots of money has been put into upgrading bus frequency and operating hours. But if a bus route has been upgraded from an hourly frequency to a half hourly frequency (making it twice as good), there’s still no reason why choice passengers will use it – it’s still not as good as a car. Until they reach the tipping point where they are as efficient (from a user perspective) as cars, buses are unlikely to be a roaring success.
It’s not all doom and gloom and you don’t necessarily need vast sums of money to get anywhere – small improvements can make a difference and big improvements needn’t be that expensive (improving off peak rail frequency for instance). I suppose my point is that policymakers need to be mindful of what the investment is targeting and how it affects quality relative to its competitors. Spending $1billion on Myki won’t get us much closer to that modal share tipping point, but spending $1billion on frequency upgrades probably would.
For a most interesting in depth look at providing quality public transport, have a look at this document from Canada, kindly sent to be by Jason.
Filed under: buses, roads, trains, trams | 41 Comments »