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From time gains to land use: the
new challenges of accessibility
modelling
Pr. Yves Crozet Laboratory of Transport Economics (LET)
University of Lyon (IEP) - France
www.let.fr
MOEBIUS Project – Final conference
Luxembourg – 23 10 2013
Introduction
• “Accessibility at point 1 to a particular type of
activity at point 2 is directly proportional to
the size of the activity at point 2 and inversely
proportional to a function of the distance
separating the two points.
• The total accessibility at point 1 to the activity
is the summation of the accessibility to each of
the points around point 1” (Hansen 1959, p.
74 ff)“
Urban mobility: some new trends
• Some paradoxical changes in urban mobility policies
• The decreasing relevancy of Cost Benefit Analysis (CBA) to define public choice
• A public preference for slow modes (tramway, bus, bikes, pedestrian streets..)
• Voluntary restrictions to car mobility (lower speed, reduced width of roads…)
• Towards a lower accessibility ? A risk for urban attractiveness?
The key ratio
• A city is a place where the number of opportunities
is higher than in other places
• Travel cost (time + money) is compared to the
corresponding amenities
• What we have to take into account is the ratio
Opportunities ____________________
Travel cost
Time gains versus land use:
what is at stake?
Objective function of
the decision maker ?
Decision-maker?
Speed and time
gains
Land use and
environment
Benevolent and
all-knowing ruler
Ignorant or
opportunist
decision maker
Time gains versus land use:
what is at stake? Objective function
of the decision
maker ?
Decision-maker?
Speed and
time gains
Land use and
environment
Benevolent
and all-
knowing ruler
Accessibility
in CBA,
transport
demand and
traffic growth
Ignorant or
opportunist
decision
maker
• We can describe accessibility as a function of
territorial structure and transport supply.
• with
• Ai = Accessibility to destinations D from point i
• Dj = Activity destinations at points j
• cij = Generalized cost (time, price…)
)( ij
j
ji cfDA
Time gains and accessibility
• The first age of accessibility is dominated by the
search of speed and especially road speed for cars.
• In this age, speed is the main factor of the
improvement of urban accessibility.
• The dream of policy makers is the same than the
dream of car drivers: to keep car accessibility
during peak hours at the same level than during off
peak hours.
Time gains versus land use:
what is at stake?
Objective function of
the decision maker ?
Decision-maker?
Speed and time
gains
Land use and
environment
Benevolent and all-
knowing ruler
Accessibility in
CBA, transport
demand and traffic
growth
Ignorant or
opportunist
decision maker
Cost efficiency
analysis of
accessibility gains
« social effective
speed”
10
« SNIT = National Scheme
for Transport Infrastructures»
Tours-Bordeaux
Public Subsidies = 5 euros/passenger
during 50 years
Marseille-Nice
Public subsidies=
35 euros/pass
during 30 years.
Social effective speed
= 15 km/h
Energy and Equity (Ivan Illich
and J.P. Dupuy 1973)
• The more you increase speed, the
more you reduce equity
• From the generalized cost to the
generalized speed or « effective
speed »
• Ef. Speed = 1 / (1/S) + (k/w))
« Effective Speed » and
« Social Effective Speed » • Average speed = harmonic
average
n/ [(1/V1)+(1/V2)]
• Effective speed of bike
• 1/ [(1/V)+(k/W)]
• 1/ [(1/14)+ (0.001/8) =
13.9
• Supersonic effective speed
• 1/ [(1/2000)+ (1/6)] =
6km/h
• High speed rail effective
speed
1/ [(1/200)+ (0.15/8)] =
40km/h
• High speed rail social
effective speed
• 1/ [(1/200)+ (0.5/8)] =
14.8km/h
• Regional train
• 1/ [(1/100)+ (0.30/8)] =
21km/h
Tramways in Paris Region within 2020
Time gains versus land use:
what is at stake?
Objective function of
the decision maker ?
Decision-maker?
Speed and time
gains
Land use and
environment
Benevolent and all-
knowing ruler
Accessibility in
CBA, transport
demand and traffic
growth
Accessibility index
and map-based
tools
Ignorant or
opportunist
decision maker
Cost efficiency
analysis of
accessibility gains
« social effective
speed”
The perverse effects of speed on
land use
• A second age of accessibility emerges when road congestion is recurrent during peak hours.
• Public transit (PT) becomes the priority to keep or to improve urban accessibility.
• Speed is therefore less important than reliability, frequency and comfort of PT.
• Even some relatively slow modes (walking, cycling) are promoted.
• Decision makers have a preference for density
ijcβ
j
ji DA
exp
« Attractive Masses »
Housing
Jobs Shops, Leisure
Generalized cost
Monetary cost +
Travel Time +
parameters
Parameter
Sensitivity to Generalised cost
Economic theory of urban accessibility
Hansen 1959, Koenig 1974
MOSART : an innovative
modelling platform for planning
sustainable mobility
MOSART (MOdeling and Simulating
Accessibility to netwoRks and Territories)
• Orthophotos
A GIS TO MODEL ACCESSIBILITY (MOSART)
• Census data
• Administratives areas
•Road network
•PT network
• Shops et services
20
21
MOSART Version 2 : case study
MOSART Version 2 : case study
Density and new apartments per municipality(1991)
Sources : SITADEL, INSEE
Density and new apartments per municipality (2007)
Sources : SITADEL, INSEE
Time gains versus land use:
what is at stake?
Objective function of
the decision maker ?
Decision-maker?
Speed and time
gains
Land use and
environment
Benevolent and all-
knowing ruler
Accessibility in
CBA, transport
demand and traffic
growth
Accessibility index
and map-based
tools
Ignorant or
opportunist
decision maker
Cost efficiency
analysis, cost of
accessibility gains,
« social effective
speed”
Accessibility maps
to open the black
box of transport
demand modelling
Road congestion during morning peak hours
Road congestion with the new
infrastructure during morning peak
hours
32
Accessibility change with the new
infrastructure
Accessibility gains
33
Accessibility change with the new
infrastructure
Accessibility gains
Accessibility gains to jobs
outside from Grand-Lyon
Road traffic in Paris 1953 and
1969
Conclusion
• The coming challenge of urban mobility is:
how public policies on land-use and
transport supply can help to keep an
acceptable level of accessibility in a context
of rising travel costs?
• From “How accessibility shapes land use”
(Hansen 1959)
• To “How land use and environment
priorities shape accessibility policies”
Conclusion (2)
• Tell me what accessibility you are ready to
promote, and how (mode ? speed ?
reliablity? density?) and for who ?
• Tell we what accessibility you are ready not
to promote, and even to reduce…
• And I’ll tell you what city you prepare for
tomorrow!
j
ijjicDA βexp
Some references • Hansen, W.G. (1959) ‘How accessibility shapes land-use’, Journal of the American
Institute of Planners, 25, pp. 73-76
• Johannsson, B., Klaesson, J., Olsson M. (2002) ‘Time distance and labour market
integration’, Papers in Regional Science, 81-3, pp. 305-327
• Koenig, J.G. (1974) ‘Théorie économique de l'accessibilité urbaine’, Revue
Economique, XXV-2, pp. 275-297
• Morris, J.M., Dumble, P.L. and Wigan, M.R. (1979), ‘Accessibility indicators for
transport planning’, Transportation Research-A, 13A, pp. 91-109
• Pirie, G.H. (1979), ‘Measuring accessibility : a review and proposal’, Environment and
Planning A, 11, pp. 299-312
• Raux, C., Souche S. (2004) ‘The acceptability of urban road pricing. A theoretical
analysis applied to experience in Lyon’, Journal of Transport Economics and Policy, 38,
Part 2, pp 191-216
• Stalinov, K. (2003) ‘Accessibility and Land Use : The Case of Suburban Seattle, 1960-
1990’, Regional Studies, 37.8, pp. 783-794
D
prix
coût
déplacements entre
zones i et j
A
O
surplus initial
T2
c2
d2
mimmi tvotcCg
2
1
ij
ij
c
c
ijijdcTS
T1
c1d1
Car speed and consumption of
space-time –(m2/h)
m2
Speed km/h
• Demand Curve ?
Wilson (1970)
k
ikk
ijj
iijcfD
cfDOT
)(
)(
k
ikki cDA exp
ijij ccf exp)(
• Accessibility
(Hansen, 1959)
• Surplus change for
zone i jzones
c
c
ijiji
ij
ij
dcTS
2
1
12
1
2
lnlnexp
exp
ln iii
j
ijj
j
ijj
ii AA
O
cD
cDO
S
• Neuburger (1971)
= Koenig (1974)
ijcβ
j
ji DA
exp
« Attractive Masses »
Housing
Jobs Shops, Leisure
Generalised cost
Monetary cost +
Travel Time +
parameters
Parameter
Sensitivity to Generalised cost
Economic theory of urban accessibility
Hansen 1959, Koenig 1974