So, to recap parts one and two. If we make transport more efficient, less polluting, or generally more pleasant, then people just travel more and wipe out the benefits. We need to manage the overall demand for travel. We can do that by changing planning so that the things we need are closer to us, and by reallocating space and resources to the modes we prefer, like walking, cycling and buses.

Are we nearly there yet?
© Jonaldm | Stock Free Images &Dreamstime Stock Photos

But, and it’s a big but, even if we created perfect towns and cities, with everything nearby, we might still all travel just as much. That’s because we also have to think about the time people spend travelling, and the fact that humans are mostly creatures of habit.

Ever since Tanner suggested the idea in 1961, there’s been an ongoing academic debate about the idea of ‘travel time budgets’. In the 1970s empirical research by the likes of Szalai and Zahavi backed up the idea that all over the world, people spend roughly the same amount of time per day travelling – about an hour.

This caused quite a bit of excitement, suggesting as it did that maybe the amount of time we’re prepared to spend travelling is somehow ‘hard wired’ into human beings. Since that original paper various theories have been suggested, and plenty of other researchers have questioned the data, saying there’s more variation within and between populations than has been suggested.

What does seem to be agreed on however is that at the individual level, we do tend to be quite resistant to changing how much time we spend travelling. A look at the national travel survey for the UK (2010) shows that travel time has remained static for the last 15 years, at just over an hour per day, while the number and length of trips has varied. And if you think about it, that has some pretty far-reaching consequences for how we think about managing the overall demand for, and impact of, travel.

Suppose we drastically shorten many of our journeys, or provide really fast, efficient trains, or use the internet to eliminate journeys altogether? Well, the evidence suggests that on an individual level, we’ll probably just make other journeys to use the travel time we saved. The likelihood is that if we shorten ‘essential’ travel, to work, or that hospital appointment, it will be replaced with leisure trips, maybe occasional longer trips to see friends or relations.

Here’s another thought, transport economics is almost entirely based on the idea of time savings. The case for a new road will typically be based on the idea that, for example, (a) each motorist will save 30 seconds off their journey time, (b) the average person’s time is worth £12 per hour to the economy, and (c) 200 million journeys per year will be made on the road. So, each 30 seconds is worth 10p, and the road is therefore worth £20 million per year to the economy.

You might think this is nonsense, because when you boil it down to the individual motorist, that 30 seconds is unlikely to really make any significant difference at all to their productivity. And I would agree with you. However, that hasn’t stopped government using the same method to justify investing billions in high speed rail.

But that logic is weakened still further if you assume that for each person, travel time per day will probably remain constant.

The upshot of all this is that we need to sustainably ‘reallocate’ any travel time that we save by speeding up or eliminating trips. It’s just the same as the need to reallocate road space if we want to ‘lock in’ the benefit of some motorists switching to other modes.

What might this look like? Well, having freed up time, if people are going to make extra ‘discretionary’ trips to use that time, we need to make sure they don’t choose to make those trips by car. We can make it attractive to walk and cycle for pleasure, to visit friends and leisure facilities. We can invest in extra capacity on the railways, rather than speed – given that you can now work, watch a film or surf the net on a train journey, why do we need to spend billions making that journey slightly shorter and massively more expensive? And we can stop chasing our tails building new roads.

Ultimately, perhaps what we need is a ‘slow travel’ movement, a bit like the ‘slow food’ movement? A shift in the focus of transport strategy, away from speed, and towards making travel healthy, low impact, and fun.

[P.S. One thing not addressed here is the impact of ‘outsourcing’ our shopping trips to delivery vans, via internet shopping. I think that will have to be the topic of another post.]

So, to recap part one, if we try to ‘fix’ transport without thinking about overall demand, we’re running to stand still. If we make cars more efficient they use less fuel, and emit less pollution, but since they’re cheaper to run we drive more miles, and we’re back where we started. If we ease congestion, people drive more. Even making public transport better has a similar effect.

‘It’s gridlock around here.’
‘Just be glad there aren’t any more elephants!’
© Roadbully | Stock Free Images & Dreamstime Stock Photos

So what’s the answer? Well, like it says in the headline, this is about space and time. If we want people to travel less, thinking about where we put things is a no-brainer. But, and it’s a big but, we also have to think about time – because it turns out human beings are not the ‘utility-maximising’ decision makers that economists like to think we are.

So, the obvious factor first … space.  There are two elements to this – putting stuff closer together, so we don’t need to travel so much, and how we allocate space on the road, to ‘lock in’ changes in travel behaviour.

Ever since geographers first started thinking about urban sprawl in the sixties, we’ve been debating its effects on transport. Hardly a week goes by without a media story about out of town supermarkets, which we all drive to, killing off the high street. But equally, there are more and more stories about urban renaissance, high density living, and those out of town supermarkets coming back into town centres with ‘metro’ stores.

Essentially, a key element in constraining our demand for transport is to change planning, to favour denser communities, that can then economically support localised services. Lots of people have written about this, but for a good discussion try this chapter from Carbon Zero by Alex Steffen. The problem with changing spatial planning is that it takes a long time to have an effect.

A less discussed side of the ‘space’ debate is how we allocate road space to different modes of transport. Reallocating road space is the often forgotten key step in creating ‘modal shift’ – i.e. getting people out of cars and into cycling, walking or buses.

Let’s say you live in a city where all the main roads in are gridlocked from 8-9am. What happens if the council launches a big push for people to use park-and-ride, or cycle in to work. A year later there are thousands of people riding the bus, or cycling in, but the gridlock is just as bad – so what happened?

Well, the answer’s simple, as some drivers switched to other modes, other drivers took their place. Congestion usually means pent up demand – there are always people who choose to make some trade off to avoid a certain level of congestion (e.g. by driving to work really early, or not travelling at all), and if the congestion level falls, they re-evaluate that decision.

If our aim is to have fewer drivers, and so less pollution, then the uncomfortable truth is that gridlock is our friend. If we succeed in getting some drivers to switch to the bus or bike, we have to reallocate the road space they were using to those modes, by putting in bus and/or bike lanes, changing priorities at junctions, removing parking or whatever. The net result will be the same level of congestion for the remaining drivers, but that means they won’t be joined by any more.

The big problem is that promoting cycling, or investing in bus services, can be seen as promoting ‘choice’, but taking space away from cars is less of a vote winner. So elected councils only tend to do half the job. Note that the thing that will actually decrease the congestion level is to increase the monetary cost of travelling at that time, with a congestion charge. That’s because the driver’s decision on whether to travel is based on both time/stress and money. Of course congestion charges haven’t exactly proved an electoral favourite either.

So, there are things we can do to decrease transport demand, and lock-in modal shift, by thinking about space, but they take time and may not be popular. However, in part 3 I’ll explain why we also have to think about travel time and human psychology, because even changing the layout and roads of our cities may still see us running to stand still.

There are lots of ways we can reduce the emissions from transport, and many of them will also make getting around more pleasurable, more efficient and easier. And therein lies the rub – because if something gets easier, we’ll probably do more of it.

It makes him scratch his head too!
© Tjenner | Stock Free Images & Dreamstime Stock Photos

Let’s take a really simple example – you replace your petrol car with an electric one. Great, now the pollutant emissions for each mile you drive have been reduced (by how much is a debate for another post). And you save money too, because electricity is much cheaper than petrol.

Now you’ve invested all this money in buying your electric car, you can drive around for next to nothing, and feel pretty smug about it too. So, all other things being equal, you’ll probably drive more miles. In the jargon it’s called a ‘rebound effect’.

Of course it’s not quite that simple. In reality, our travel behaviour is influenced by all sorts of complex factors, but the simple fact is, travelling has costs and benefits. If we reduce the costs – time, money, stress – then people are likely to travel more to grab more of the benefits. That might mean buying a nicer house that’s further from your job, or making more leisure trips.

None of this is rocket science (now that would really increase total miles travelled). But when the solutions to our transport problems are debated, how often do you hear serious debate about reducing, or at least managing, the overall demand for transport?

Whether it’s hard-shoulder running on the M6, biofuels for aviation, high-speed rail or electric cars, the implicit assumption is that we can reduce the impacts of our current transport patterns. But time after time, we find that by the time the latest ‘solution’ is implemented, its benefit has already been negated by an increase in total miles travelled.

The roads protesters of the 90’s understood this, a central part of the case against the ‘roads for prosperity’ programme was that new roads just lead to more traffic. But that argument rarely strayed beyond the professional transport community – the media were only interested in tree-houses and Swampy, and the politicians only axed the programme because they realised it was going to cost a fortune in security guards. (It looks like we’re about to see a re-run of that scenario, but I doubt the debate will have moved on much.)

So what’s the answer? Will we forever be running to stand still? Transport emissions remain stubbornly high, and I would argue that rebound effects are a large part of the reason. Without a serious debate about overall transport demand we’ll never make progress.

There is work going on to address the issue, but it’s hardly part of the mainstream. At an event recently I found myself talking to someone from the Department for Transport, and I was delighted (and surprised, I admit) to discover that she was part of a team looking at overall demand management. It’s a good sign, but the cynic in me doubts whether they’ll ever be listened to seriously by the ministers.

In part two I’ll go on a journey in space and time, to consider how it might be possible to make transport better without making us want more of it!