Feb 2009 1

Travel Time and Sustainable Travel Behaviour

David MetzCentre for Transport StudiesUniversity College London

Feb 2009 2

National Travel Survey

• 7-day travel diaries recording personal travel

• Annual sample of 20,000

• Since 1972

• Longest time series; high quality

• Excludes international air travel

• Measures ‘daily travel’

Feb 2009 3

Travel time, hours per person per year

-

50

100

150

200

250

300

350

400

450

500

1970 1975 1980 1985 1990 1995 2000 2005 2010

ho

urs

pe

r p

ers

on

pe

r y

ea

r

Feb 2009 4

Distance & journeys per person per year

-

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

1970 1975 1980 1985 1990 1995 2000 2005 2010

distance, miles per person per year

trips per person per year

Feb 2009 5

Trips by age

0

200

400

600

800

1000

1200

1400

<17 17-20 21-29 30-39 40-49 50-59 60-69 70+

Tri

ps

pp

py

Feb 2009 6

Trips (pppy) according to car ownership

0

200

400

600

800

1000

1200

0 1 2

cars per household

trip

s p

pp

y

Feb 2009 7

Trips (pppy) according to income

0

200

400

600

800

1000

1200

1400

1 2 3 4 5

household income quintiles

trip

s p

pp

y

Feb 2009 8

Main journey purpose, trips pppy

2006 1985-86

shopping 219 210

visiting friends 168 191

commuting 160 178

education 106 109

personal business 105 97

other escort 97 74

all journeys 1037 1034

Feb 2009 9

Travel spend (% of household spend)

0

2

4

6

8

10

12

14

16

18

20

1980 1985 1990 1995 2000 2005 2010

Tra

vel a

s p

rop

ort

ion

of

ho

use

ho

ld e

xp

en

dit

ure

Feb 2009 10

Business-as-usual scenario• Travel time: an hour a day• Journeys: 1000 a year• Journey purposes: unchanged • Spend: 16% of household spend• Incomes: double over 30 years• Technology: incremental improvement +

decarbonisation• Car ownership increase?• Distance travelled?

Feb 2009 11

Personal mobility: miles pppy

0

1000

2000

3000

4000

5000

6000

7000

8000

1860 1880 1900 1920 1940 1960 1980 2000 2020

Feb 2009 12

Delays for slowest 10% of journeys on Strategic Road Network

Feb 2009 13

Hypothesis: daily travel demand has saturated

• Access and choice increase with square of speed

• Value of additional choice characterised by diminishing marginal utility

• Prediction: sufficient choice experienced through mobility

Feb 2009 14

FIGURE 3.9

Proportion of the UK urban population with a choice of one, two, three or fourgrocery stores each with a different fascia and larger than 1,400 sq metres

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Drive-time (mins)

Pe

rce

nta

ge

of

po

pu

latio

n

One or more Two or more Three or more Four or more

Source: CACI Limited analysis of parties’ data submissions – from Competition Commission: The supply of groceries in the UK market investigation report, May 2008.

Feb 2009 15

Choice of schools and hospitals

• Over 80% of pupils have at least 3 secondary schools within 5km of home

• Secondary schools have 6 others within 10min drive time

• 40% of population have up to 2 hospitals within 15min drive time; 90% within 60min

Feb 2009 16

Business-as-usual scenario (2)

• Stable behaviour in aggregate: – 7100 miles – 1000 trips – 380 hours a year on average

• But road traffic continues to grow….

Feb 2009 17

Growth 1996-2006

• Distance pppy (NTS) 0.2% pa

• Vehicle km 1.3% • Cars 2.6%• Population 0.4%

• Traffic growth due mainly to increase in car ownership

• Distance per incremental car = ½ average

Feb 2009 18

Sustainable travel

• Stable personal travel – travel demand saturated.

• Some car ownership increase by ‘late adopters’, as car use approaches saturation. Some mode switch to cars.

• Decarbonise transport system.

• Manage congestion.

Feb 2009 19

Transport policy and operations

• Interventions which have the effect of increasing speed lead to increased access

• Interventions which have the effect of reducing speed tend to reduce access and choice

• ‘Smart choices’ tend to involve speed reduction

• Decarbonisation will need to rely mainly on technology

Feb 2009 20

Managing congestion

• Can’t build our way out of congestion

• Road pricing redistributes road space in favour of those who can afford to pay– Improved access for payers (induced traffic)– Reduced access and choice for non-payers– Likely to be unpopular

• Main problem is journey time uncertainty

Feb 2009 21

Conventional transport economics

• Main benefit is ‘travel time saving’• Underestimates ‘induced traffic’….• ….and carbon, accidents and other detriments• Travel a ‘derived demand’• Agglomeration benefits• Modelling assumes minimisation of ‘generalised

costs’• Neglects behavioural economics

Feb 2009 22

References

• The Myth of Travel Time Saving, Transport Reviews 28(3),321-336, 2008

• Responses to ‘Myth’ in November issue • The Limits to Travel, Earthscan, 2008• www.limitstotravel.org.uk• National road pricing: a critique and an alternative, Proc

Inst Civil Eng: Transport 161(TR3), 167-174, 2008• Sustainable Travel Behaviour, UTSG January 2009• Papers from david.metz@transport.ucl.ac.uk