Which tools for which purposes?

Transcription

1 Which tools for which purposes? An historical perspective on data recollection, transportation modeling and economic assessment Hadrien Commenges Quanturb Seminar 29 octobre 2014 Hadrien Commenges Which tools for which purposes? 1 / 31

2 Contents 1 The technical matrix 2 Data recollection procedures 3 Modeling procedures 4 Economic assessment procedures 5 The transportation planning process 6 Modeling the transportation planning process Hadrien Commenges Which tools for which purposes? 2 / 31

3 The technical matrix Economic assessment Data recollection Forecast modeling CBA with time savings Household travel survey Four-step model Hadrien Commenges Which tools for which purposes? 3 / 31

4 Data recollection procedures Count No interaction counter / counted Survey Interaction counter / counted Count-trajectory Traffic between set of points Count-point Commuting OD survey Traffic at one point Non time-stamped links Time-stamped links Cordon survey Screen line Flagrante interview HTS and similar Non flagrante interview Hadrien Commenges Which tools for which purposes? 4 / 31

5 Data recollection procedures Transit traffic Study area Resident trip: internal Non resident trip: internal Non resident trips: from-to-out Resident trips: from-to-out Hadrien Commenges Which tools for which purposes? 5 / 31

6 Data recollection procedures Counts Semantic information Non resident population Non existent infrastructure - x - Cordon or screen survey x x - Household travel survey x - x Hadrien Commenges Which tools for which purposes? 6 / 31

7 Data recollection procedures Enquête de circulation de Rennes, 1960 Manual of Procedures for Home Interview Traffic Studies, 1944 Hadrien Commenges Which tools for which purposes? 7 / 31

8 Modeling procedures Main modeling approaches: Growth-factors (Fratar, Furness) Four-step models Accessibility models Activity-based models Structure of the four-step model (without retroaction loops): Generation Distribution Modal choice Assignment Exogeneous hypothesis OD matrix margins OD matrix (all modes) OD matrices by mode (PV, CT) Flows assigned to network Hadrien Commenges Which tools for which purposes? 8 / 31

9 Modeling procedures 1 st step: trip generation Normative values Linear regression at zones level Linear regression at household level The following equation may be read at household or at zonal level: D = β 0 + β 1 INC + β 2 NP + β 3 NV D INC NP NV Number of trips generated (by household / by zone) Income (household / zone) Number of people (household / zone) Number of vehicles (household / zone) Hadrien Commenges Which tools for which purposes? 9 / 31

10 Modeling procedures 2 nd step: trip distribution Growth-factors (Fratar, Furness) Gravity model Intervening opportunities The initial gravity model: The reformulated gravity model: T ij = k P ip j D 2 ij T ij = α i β j E i A j f (C ij ) Hadrien Commenges Which tools for which purposes? 10 / 31

11 Modeling procedures 3 rd and 4 th steps: modal choice and traffic assignment Modal choice and route choice considered as a rational decision: Minimizing distance (initial approach) Minimizing time (intermediate approach) Minimizing generalized cost (final approach) Hadrien Commenges Which tools for which purposes? 11 / 31

12 Economic assessment procedures Generalized cost (first glance) Generalized cost (C g ) and generalized time (T g ) as composite values: C g = p + λt T g = t + p λ p t λ Financial cost Time Value of time The value of time may vary depending on: Kinds of time (moving time, waiting time) Trip purposes (work, shopping, leisure) Catories of individuals (adults / children, occupational category) Hadrien Commenges Which tools for which purposes? 12 / 31

13 Economic assessment procedures Measuring the value of time Normative values vs. Revealed preferences vs. Declared preferences Hadrien Commenges Which tools for which purposes? 13 / 31

14 Economic assessment procedures Time savings as a yardstick Introduction of time savings in CBA analyses (1950s-1960s): Jusque-là on calculait la rentabilité d une infrastructure de transport de façon classique: ce que ça rapporte moins ce que ça coûte. Comme ça coûtait toujours plus cher que ça ne rapportait, la rentabilité était toujours négative. Donc on s est mis à calculer la rentabilité généralisée. Entretien avec Pierre Merlin, 21 avril Hadrien Commenges Which tools for which purposes? 14 / 31

15 Economic assessment procedures Time savings as a yardstick Use of time savings in CBA analyses (2012): Avant la mise en service du projet en 2017, on estime que 6,4 millions de voyages par an se déroulent dans des conditions d inconfort. Pour ces utilisateurs, le temps moyen passé en situation d inconfort est de l ordre de 15 minutes. Selon la méthode de valorisation en vigueur, il est estimé qu un usager de la ligne 13 en situation d inconfort a la perception que le temps de son trajet est en moyenne 50 % plus long que sa durée réelle. Après la mise en service du prolongement de la ligne 14, plus aucun utilisateur ne voyagera en situation d inconfort, ce qui correspond à un gain de temps annuel estimé à 0,8 million d heures. STIF et RATP, Prolongement de la ligne 14, Hadrien Commenges Which tools for which purposes? 15 / 31

16 Economic assessment procedures The myth of travel time saving Jules Dupuit (1844): utility of a good defined as le sacrifice maximum que chaque consommateur serait disposé à faire pour se le procurer. Cost Supply Consumer surplus Producer surplus Equilibrium Demand Quantity Hadrien Commenges Which tools for which purposes? 16 / 31

17 Economic assessment procedures The myth of travel time saving Cost DEFINITION OF SURFACE AREAS S 1 Supply improvement Benefits with constant demand (cd) C 1 S 2 C 2 C' 2 Benefits of induced users (i) D Recongestion due to induced traffic (r) T 1 T 2 Traffic CONSUMER SURPLUS With constant demand Consumer surplus = cd With new equilibrium Consumer surplus = cd + i - r Hadrien Commenges Which tools for which purposes? 17 / 31

18 Economic assessment procedures The myth of travel time saving Cost S 1 Supply improvement S 2 C 1 C 2 D 2 D 1 Growth of demand T 1 T 2 T f Traffic Hadrien Commenges Which tools for which purposes? 18 / 31

19 The transportation planning process What trips are taken into account in the TTP? 6,1 % Immobile 93,9 % Mobile 35,5 % 64,5 % Non motorized Motorized 12,1 % 87,9 % Intra-zone Inter-zone 54,9 % Other purpose 69,4 % 30,6 % Off-peak hour Peak hour 45,1 % Professional 58,5 % Off-peak hour 41,5 % Peak hour Trips taken into account in the TPP Trips not taken into account in the TPP 20 % 20 % Proportion of individuals Proportion of trips Interpretation: among the residents of IdF region, 93.9 % are mobile. Among the trips made by mobile people, 64.5 % are motorized. Among the motorized trips, 87.9 % are made between zone (inter-zone)... Hadrien Commenges Which tools for which purposes? 19 / 31

20 Non motorized Other Motorized Other Work Other Work Work The transportation planning process What is the value of the trips taken into account in the TTP? (a) Categories of trips (% of trips) (b) Categories of trips (% of value) Intra-zone Intra-zone vs. Inter-zone Inter-zone Peak hour Peak vs. Off-peak hour Off-peak hour % % Transportation mode % % Trip purpose Trip purpose % % % % Peak hour Off-peak hour Peak hour Peak vs. Off-peak hour Off-peak hour Hadrien Commenges Which tools for which purposes? 20 / 31

21 The transportation planning process Impact of the TTP on the network (mode) Total length of the network (km) Highway Urban expressway Year Hadrien Commenges Which tools for which purposes? 21 / 31

22 The transportation planning process Impact of the TTP on the network (mode) Il y avait une très grosse ambiguïté dans ces modèles, c est qu on avait copié sans s en apercevoir la finalité des modèles à l américaine. Or, ces modèles ont été conçus pour permettre aux ingénieurs de justifier leurs projets d infrastructures routières. (OPDT, 15 avril 2011) Les modèles utilisés valorisaient fortement un aspect, celui du surplus de l usager, qui conduisait à valoriser la voiture. Dans un certain nombre d esprits, une sorte de lien direct s est établi: l intérêt économique, c est le tout-voiture. (JGK, 13 juin 2011) Hadrien Commenges Which tools for which purposes? 22 / 31

23 The transportation planning process Impact of the TTP on the network (shape) Il est nécessaire de constituer un réseau adapté à cette agglomération [... ] un réseau, et non pas un faisceau de radiales. (SDAURP, 1965) Hadrien Commenges Which tools for which purposes? 23 / 31

24 Modeling the transportation planning process The status of the network in various modeling approaches Flows Land use Transp. network Travel demand modeling Land use - transport interaction Evolving networks Endogeneous Exogeneous Hadrien Commenges Which tools for which purposes? 24 / 31

25 Modeling the transportation planning process The emergence of hierarchy in transportation networks Yerra and Levinson calculate a set of 4 models on a regular squared grid: 1 Travel demand model: calculates the flows (simplified four-step model) and assign them to the network (all-or-nothing). 2 Revenue model: calculates the revenue produced by each link (multiplication flow, toll). 3 Cost model: calculates the cost of maintenance of each link (growing function of flow, speed, length). 4 Investment model: calculates the investment based of revenue and cost and assign investment to speed increase/decrease of each link. Conclusion: the hierarchy is an emergent property and not the result of the transportation planning process. Hadrien Commenges Which tools for which purposes? 25 / 31

26 Modeling the transportation planning process A simple deterministic model with one mecanism called SERT Regular non-circular grid (no periodic boundary conditions) Von Neumann neighborhood 100 vertices edges Entities: Vertices Edges Attributes of the entities: Vertices Links Production Attraction Distance _ Friction Set up at initialization Modified dynamically Updated time matrix Flows estimation Economic assessment Network modification Productions and attractions Initial constant time matrix Flows assigned to the network Selection of the link with the highest surplus Hadrien Commenges Which tools for which purposes? 26 / 31

27 Modeling the transportation planning process Model assessment: SERT vs. Null model with connexity constraint Basic indicators: Meshedness indicator (α = Γ/Γ max ) Complexity indicator (β = E/N) Connectivity indicator (γ = E/E max ) Universal form indicators (Roth et al., 2012): Core characteristics: average degree of core vertices equals 2.5 and 60 % of the core vertices with degree k = 2. Branches characteristics: number of branches equals to squared root of the number of vertices and the number of branches vertices equals to half the total number of vertices. Hadrien Commenges Which tools for which purposes? 27 / 31

28 Modeling the transportation planning process Focus on the meshedness indicator The classical meshedness indicator isn t suited to assess the model: we need to set a Γ max knowing the number of edges (and not vertices) in a specific topology (regular grid with VN neighborhood). Lay.1 Lay.2 Lay.3 Lay Number of edges v 1 = (4) v 2 = (3, 3, 2) v 3 = (3, 2, 3, 2, 2) v 4 = (3, 2, 2, 3, 2, 2, 2) Length of the vector v n = v n Values of the vector v n [1] = 3 v n [n] = 3 v n [k] = 2 Generating a regular grid layer by layer (4 layers in this example) from top to bottom (arrow), the number in the cells is the number of edges necessary to build an elementary cycle. Ex.: for a network with 10 edges, the max number of elementary cycles is 3. Hadrien Commenges Which tools for which purposes? 28 / 31

29 Modeling the transportation planning process Model assessment: SERT vs. Null model with connexity constraint A hierarchic non meshed structure: Modèle vide Meshedness Modèle vide Complexity Modèle SERT Connectivity Modèle vide Modèle SERT Modèle SERT Iterations Hadrien Commenges Which tools for which purposes? 29 / 31

30 Modeling the transportation planning process Reproducing the universal form ON THE GRID WITHOUT GRID WIDENING SIZE (15 2 ) FIXED SIZE (10 2 ) Hadrien Commenges Which tools for which purposes? 30 / 31

31 Conclusions Stability of the technical matrix Recent evolution from time savings to accessibility measures Recent evolution from CBA to multi-criteria analysis What do we really know about the use of modeling in policy-making? Hadrien Commenges Which tools for which purposes? 31 / 31