Campaigners criticise "self-fulfilling prophecy" as Department for Transport predicts decline in cycling

Should DfT try to predict the future, or prevent it?

by John Stevenson   November 8, 2013  

Traffic lights (CC licensed image by @Doug88888:Flickr)

The CTC has criticised the Department for Transport’s latest predictions of increased car use and a drop in cycling over the next 25 years as a “self-fulfilling prophecy”.

Writing on the CTC’s website, campaigner Chris Peck explains that the Department for Transport’s National Transport Model (NTM) forecasts a 43 percent increase in car use by 2040, but a gradual fall in cycling after an increase over the next few years.

“Traffic modelling is a dark art,” writes Chris. “Forecasting is tricky: feedback loops and unknown future changes can rapidly upset any firm conclusions about current trajectories.”

Underlying the predicted increase in car use, the modellers say, is the assumption that there will be "no change in government policy beyond that already announced."

Chris writes: “The problem, however, is that although the NTM is only supposed to be a guide to what might happen, it is treated by policy makers as the inevitable outcome that we must plan for.

“This is the 'predict and provide' approach that, in essence, is a self-fulfilling prophecy: your model predicts that car use will continue untrammelled, and further predicts huge congestion problems that might result. So, in order to prevent that congestion, you build new roads and plan new developments around everyone driving for 2/3rds of their trips and, decades later, hey presto: that's what happens!”

But it doesn’t always work. The Department predicted a fall in car traffic in London of 1.5 percent between 2003 and 2010. In fact London car traffic fell 7.8 percent as a result of investment in public transport, congestion charge and other measures intended to stop London from completely grinding to a halt.

Given all that, what’s the NTM predicting for cycling? A decline. That’s bad news, because the predicted increase in car travel is the rationale for the spending on roads announced earlier this year. As Chris Peck points out, that means the increase is therefore likely to happen.

If the NTM were predicting an increase in cycling, planners might decide to build more cycling facilities, but instead they predict a decline in cycling and walking trip lengths.

But the CTC and other transport experts doubt the validity of the DfT’s modelling.

Chris Peck points out that the 2010 figure for cycling trip length is already wrong. Average cycle trip length in 2010 was 2.8 miles and it’s risen since then, Peck says the prediction “defies recent changes in trip length which have seen cycle trips increase by 50% (2.2 miles to 3.3 miles) over the last ten years, whereas car trips remain unchanged in length (8.4 miles long average).”

Phil Goodwin, emeritus professor of transport at University College London, is also unimpressed. He told The Times: “It is not just that they got the numbers wrong, they got the direction of change wrong, which seems to me to be a much bigger problem. If it says it is going down when it is going up, there is something seriously wrong with the model.”

CTC policy director Roger Geffen said: “The self-fulfilling predictions of the National Transport Model are seriously undermining the case for quality cycle facilities. By assuming that motor traffic will increase massively while cycle use remains static, it ensures that councils’ computer programmes say ‘no’ to cycle facilities.”

Chris Peck says the example of the model’s failure in London is salutary. “If they can get it so wrong in London, the estimates of the rest of the country could be equally rotten. With cycling growing - and growing fast - and car use stagnant or declining, the NTM's continuing assumption of ever increasing motor traffic looks backward and in need of fundamental overhaul.”

As writer Ray Bradbury - famous for the dystopian novel Fahrenheit 451 - once said, “People ask me to predict the future, when all I want to do is prevent it.” Maybe the DfT should take a leaf out of Bradbury’s book.

19 user comments

Oldest firstNewest firstBest rated

Historical DfT traffic forecasts against reality
http://www.bettertransport.org.uk/blogs/roads/170412-phil-goodwin-ltt

posted by CarlosFerreiro [54 posts]
8th November 2013 - 13:21

like this
Like (21)

We shouldn't worry too much about the DfT predictions because of one little known fact.

When a 5 percent gap appears between supply and demand of an inelastic commodity (in this case, oil) the resultant cost increase is 400 percent. In other words, once the world's oil producers fail to keep up with the inexhorable demand we will see pump prices well beyond what many motorists can afford.

With the price of everything we buy on the rise, and with wages stagnating, people may still have access to cars, but will use them far less. Lots of drivers I know are already cutting down on their mileage and trying to drive more economically.

There will be a massive increase in cycling, but we will also see an increase in bicycle KSIs, as waves of inexperienced cyclists fill the streets, mixing it with an increasingly lawless style of driving similar to that found in many other countries, whilst law enforcement resources are taken away from roads and redeployed to cope with criminal gangs and terrorism. Segregation is the key.

I don't know where how the DfT has arrived at their prediction, but if I went into Ladbrokes and tried to lay a bet on a massive increase in cycling over the next twenty years they'd tell me, "sorry mate, we don't take bets on dead certs".

"Hey..... Let's be visible out there."

Neil753's picture

posted by Neil753 [451 posts]
8th November 2013 - 14:22

like this
Like (12)

Neil753 wrote:
We shouldn't worry too much about the DfT predictions because of one little known fact.

Thing is the politicians are still wedded to the idea that traffic growth is good, that cars mean prosperity.

What i am a little concerned about is how politicians intend to deal with no petrol/diesel duty though. It is a nice little earner, and even if fossil fuel use falls i am doubtful that car use will stop. The average journey is 8miles, well within the capability of current electric cars.

I accept that the current technology can't match IC engines, and i doubt it ever can due to the energy density of hydrocarbons.

So politicians will have to raise other taxes,

mrmo's picture

posted by mrmo [1022 posts]
8th November 2013 - 14:30

like this
Like (7)

I haven't read the report however the article is confusing.

The graphics relate to trip length. A reduction in average trip length could result either from the same number of trips (but shorter) or an additional number of short trips. The latter would be consistent with trips moving to bicycle from car in urban areas, which would also be consistent with increased average trip lengths for cars. Which would be a good thing surely?

To draw a sensible conclusion you would need to look at trends in overall kilometers travelled by mode as well. A split between intra urban and inter urban journeys would also be informative. Presumably Mr Peck has done that before castigating the DfT but the article doesn't make this clear.

Transport modelling is indeed difficult and modelling changes in proportionally very small numbers as bicycle trips are is even more so. Interpreting the results, well....

posted by Nixster [61 posts]
8th November 2013 - 14:45

like this
Like (7)

mrmo wrote:
. The average journey is 8miles, well within the capability of current electric cars.

I accept that the current technology can't match IC engines, and i doubt it ever can due to the energy density of hydrocarbons.

So politicians will have to raise other taxes,

Agree largely with your comments. Just wanted to point out David McKay's graph showing the energy consumption for different modes of travel:
http://www.withouthotair.com/c20/page_128.shtml

and his comments on possible problems with electric car use:
http://www.withouthotair.com/c20/page_131.shtml

He seems largely optimistic that this will be the future. So anyone pinning their hopes on bicycle travel being facilitated by the disappearance of cars due to hydrocarbon scarcity needs to think again.

posted by Ush [377 posts]
8th November 2013 - 15:17

like this
Like (8)

How much money does the cycling lobby have compared with the road lobby?

What does cash make? Government policy.

posted by Sanderville [199 posts]
8th November 2013 - 15:23

like this
Like (5)

Number crunchers, don't you just love them!

antonio

antonio's picture

posted by antonio [930 posts]
8th November 2013 - 15:33

like this
Like (6)

mrmo wrote:
The average journey is 8miles, well within the capability of current electric cars.

I accept that the current technology can't match IC engines, and i doubt it ever can due to the energy density of hydrocarbons.

I share the use of a Nissan Leaf, when I'm not on my bike, and very nice it is too. But an electric car, once manufacturing and electricity generation is taken into account, produces around 90 percent of the CO2 that a conventional car uses over its lifetime, and those figures don't take into account the CO2 produced in extra "employment hours", energy consumption and indirect costs such as childcare to amass the cash to pay the electric car premium.

But, again, the answer lies with the humble bicycle, even for longer trips. An electric assisted velomobile can have a range of 400 miles, at a speed of 50mph, using a lithium battery the size of a shoe box, making it 80 times as efficient as a Nissan Leaf, and affordable for the masses through appropriate economies of scale. In fact, developments with "spray on" solar cells could easily result in the surface skin of a velomobile being able to produce more energy than it requires, even at relatively high speeds. All it would take would be a lifting of the speed restriction for electric assisted bicycles for these developments to be taken seriously as a viable alternative to long distance single occupancy car use.

I suspect the loss of fuel duty revenue will be a tough one to crack. My opinion is that it will be replaced by road pricing. All new cars could be fitted with a "black box", and compulsory retro-fitting at the next MOT test would take care of the rest. From there, it would be easy to legislate for telemetrics based insurance, linking poor driver behaviour directly with higher premiums.

But whatever the future holds, bicycles will play a key part in our transition to a low carbon economy.

"Hey..... Let's be visible out there."

Neil753's picture

posted by Neil753 [451 posts]
8th November 2013 - 15:45

like this
Like (8)

Sanderville wrote:
How much money does the cycling lobby have compared with the road lobby?

What does cash make? Government policy.


You've hit the nail on the head. The thing is, without predictions of traffic growth, the government would be not be able to award lucrative contracts to their mates, for road construction projects. This is how it works. It's a murky world but the mere fact that "consultancy fees" for widening the M25 were in excess of 100 million alone, gives some clue to the amount of public money being syphoned off to ex school chums.

If they had "consulted" me, as an HGV driver, I would have told them that traffic round the M25 was actually falling, so widening the motorway would be a waste of taxpayers cash. And my "consultation" would have been free.

"Hey..... Let's be visible out there."

Neil753's picture

posted by Neil753 [451 posts]
8th November 2013 - 16:07

like this
Like (12)

Neil753 wrote:
If they had "consulted" me, as an HGV driver

You know, I've never been "consulted" on anything. I don't recall anybody I know ever being "consulted" either.

So just who the hell are they "consulting"?

posted by farrell [1278 posts]
8th November 2013 - 16:13

like this
Like (2)

farrell wrote:
Neil753 wrote:
If they had "consulted" me, as an HGV driver

You know, I've never been "consulted" on anything. I don't recall anybody I know ever being "consulted" either.

So just who the hell are they "consulting"?

You find most consultations are usually listed on Government/Council web sites. If you don't go to the web site on purpose or subscribe to their feed, then you most likely wouldn't know they were consulting.

posted by JeevesBath [106 posts]
8th November 2013 - 16:27

like this
Like (5)

Neil753 wrote:

I suspect the loss of fuel duty revenue will be a tough one to crack. My opinion is that it will be replaced by road pricing. All new cars could be fitted with a "black box", and compulsory retro-fitting at the next MOT test would take care of the rest. From there, it would be easy to legislate for telemetrics based insurance, linking poor driver behaviour directly with higher premiums.

But whatever the future holds, bicycles will play a key part in our transition to a low carbon economy.


I mostly agree, but it won't be by compulsory black box fitting to existing cars. It will be by EU legislation making black boxes mandatory for all new cars sold in the EU, therefore washing it in over a decade or so.

Boardman CX Team '14 | Cannondale CAAD8 '12 (written off, SMIDSY) | Scott Sportster '08

Gizmo_'s picture

posted by Gizmo_ [738 posts]
8th November 2013 - 17:25

like this
Like (3)

Surprising, considering the predicted 10m growth in population, nearly all of which will be in the South East, mostly in and around London. The work these people will be doing, if any, will be low paid. They won't be affording cars. And they'll be coming from countries far more used to using bikes as utility vehicles.

So basically, I'm saying that 10m potential cycling commuters are arriving in the next 10 years. There will be bikes everywhere.

posted by racyrich [112 posts]
8th November 2013 - 17:53

like this
Like (9)

Where the f**k are these 40% extra cars going to drive, the roads are full already. TFL seems not to have noticed that car ownership is already dropping in London due to the overall pain that is driving and parking in London.

posted by kie7077 [420 posts]
8th November 2013 - 18:27

like this
Like (6)

"...developments with "spray on" solar cells could easily result in the surface skin of a velomobile being able to produce more energy than it requires, even at relatively high speeds..."

Sorry mate, I'm afraid you haven't checked your sums. Have a look at the specs, speeds and extreme geometry of Solar Challenger-type racers. But fear not: the energy density of food is similar to that of fuel, so if you cannot go the distance on PV ... you can at least pedal there.

posted by rookybiker [28 posts]
8th November 2013 - 21:41

like this
Like (6)

How on earth can any model predict the average length of cycle trips dropping as e-bike sales rise and other countries predict that trip lengths will increase?

posted by bambergbike [84 posts]
8th November 2013 - 22:10

like this
Like (3)

kie7077 wrote:
Where the f**k are these 40% extra cars going to drive, the roads are full already. TFL seems not to have noticed that car ownership is already dropping in London due to the overall pain that is driving and parking in London.

The longer car journeys do actually reflected the longer searches for a parking place!
Want to prank a motorist? Tell him, there is a free parking space down the road, third turn on the left, down to the round about next right... Laughing

posted by Dr. Ko [109 posts]
9th November 2013 - 3:37

like this
Like (3)

Traffic forecasts are notoriously unreliable. The DfT's predictions should be taken with a pinch of salt.

Fuel prices will continue to rise over the long term as oil companies have to switch production to more difficult to access sources. And alternative fuel vehicles or electric vehicles won't be that cheap to run. Like others have mentioned, I also know many people who are getting more serious about minimising their fuel consumption on grounds of rising cost. Many people are waking up to the health risks of inactivity and the authorities are keen for people to be less lazy and have lots of publich health campaigns on exercise. Put that together and it looks likely cycling will increase.

Note though that many of those moving to the South East of England from other countries will wish to buy cars, even if their income can barely afford them.

OldRidgeback

posted by OldRidgeback [2125 posts]
9th November 2013 - 10:42

like this
Like (2)

rookybiker wrote:
"...developments with "spray on" solar cells could easily result in the surface skin of a velomobile being able to produce more energy than it requires, even at relatively high speeds..."

Sorry mate, I'm afraid you haven't checked your sums. Have a look at the specs, speeds and extreme geometry of Solar Challenger-type racers. But fear not: the energy density of food is similar to that of fuel, so if you cannot go the distance on PV ... you can at least pedal there.


I'm not sure you understood the point I was trying to make. Solar Challenge type racers are very different to velomobiles, which are essentially a recumbent with an aerodynamic shell, which can be electrically assisted. Potential range is determined by the overal efficiency of the solar array, the chemical energy stored in the onboard battery, and the mechanical and aerodynamic efficiency of the velomobile. Spray on cells would only need to be 15 percent efficient, averaged out over the surface of a typical velomobile. But this is largely academic, since a velomobile might have a range of 400 miles on a battery the size of a shoe box, so most users would not need to go down the solar route at all.

"Hey..... Let's be visible out there."

Neil753's picture

posted by Neil753 [451 posts]
9th November 2013 - 14:51

like this
Like (3)