feb 20091 travel time and sustainable travel behaviour david metz centre for transport studies...
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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 [email protected]