Car Ownership Models Meeghat Habibian History and Analysis Transportation Demand Analysis Lecture note Car Ownership Models History and Analysis Meeghat Habibian

Outline Current situation Stakeholders Situation in transportation planning Model types TRRL model Betes model Transportation Demand Analysis- Lecture note 1/21

Current situation USA Europe World Iran 1/21 Transportation Demand Analysis- Lecture note 1/21 World Iran

Stakeholders Car manufacturers Consumer valuation of attributes of cars that are not yet on the market. Oil companies Future demand for their products and might benefit International organizations (e.g., World Bank) Assist in investment decision-making. National governments (notably the Ministries of Finance) Forecasting tax revenues and impact of changes in taxation. Traffic and environmental departments of regions Energy consumption, Urban traffic congestion, Forecasting transportation demand, Crash fatalities and air pollution Transportation Demand Analysis- Lecture note 2/21

Situation in Transportation planning Transportation planning process: Socio-Economic and Land Use O-D Survey Study Area Travel Demand Modeling, Trip Forecasting, Model Validation Detecting the Existing Situation (Do Nothing) Preparing Models Of Scenarios Network and Transit Modeling Trip Forecasting And Assignment Future/Scenarios Scenarios Assessment Land Use TDM and TSM Scenario Combination, Assessment and Final Suggested Plan Scenario Selection Evaluation Criteria Definition Study Area O-D Survey Network and Transit Modeling Car Ownership Models Detecting the Existing Situation (Do Nothing) Transportation Demand Analysis- Lecture note Land Use Preparing Models of Scenarios TDM and TSM Trip Forecasting And Assignment Future/Scenarios Trip Forecasting And Assignment Future/Scenarios Evaluation Criteria Definition Scenarios Assessment Scenario Selection Scenario Combination, Assessment and Final Suggested Plan 3/21

Modeling approaches Static vs. Dynamic models Aggregate vs. Disaggregate Models Long-term vs. Short-term Models Transportation Demand Analysis- Lecture note 4/21

Model types: 5/21 Car Ownership Models Aggregate Disaggregate Cohort model Time Series model Car Market Model Static disaggregate models Static disaggregate car type choice models Transportation Demand Analysis- Lecture note Panel data models 5/21

Transportation Demand Analysis Lecture note Aggregate Models

Time Series Models Development of car ownership over time Sigmoid-shape Button et al. (Button et al., 1993) Ingram and Liu (1998), double logarithmic specification to explain car and vehicle ownership in many countries and cities across the world. National Road Traffic Forecasts (NRTF) in the UK (Whelan et al., 2000, Whelan, 2001), aggregate model builds on the earlier UK work in applying a logistic curve for saturation Dargay and Gately (1999), flexible Gompertz function to predict the motorisation rate (the number of cars per 1,000 persons) Transportation Demand Analysis- Lecture note 6/21

Cohort Models Segment the current population into groups: Time based cohorts (e.g., 5 year cohorts) Location based cohorts (e.g., zonal based) … Van den Broecke (1987) for the Netherlands, combination of a cohort survival model and an econometric model Madre and Pirotte (1991) Transportation Demand Analysis- Lecture note 7/21

Car Market Models Same as time series models, but distinguishes between demand for cars and supply of cars in the car market Sigmoid-shape Mogridge (1983), Cramer and Vos (1985), car ownership depends on car prices, income, the variation of income and the development over time in the utility of using a car Berry et al (1995), which is a model of the market for new cars only Transportation Demand Analysis- Lecture note 8/21

Transportation Demand Analysis Lecture note Disaggregate Models

Static Disaggregate Car Ownership Models Contains discrete choice models that deal with the number of cars owned by a household Hague Consulting Group (1989), the Dutch national model system (LMS) for transport, binary logit models as follows Bhat and Pulugurta (1998) Hague Consulting Group (2000), the car ownership model for Sydney Transportation Demand Analysis- Lecture note 9/21

Static Disaggregate Car Type Choice Models - This category contains discrete choice models that deal the choice of car type of the household, given car ownership. Page et al. (2000) for new vehicle purchasing Birkeland and Jordal-Jørgensen (2001) Transportation Demand Analysis- Lecture note 10/21

Panel Data Car Ownership Models Reveals the change in travel behavior of individuals Needs detail individual data Kitamura (1989) Hanly (2000) Woldeamanuel (2009) Dargay (2007) Transportation Demand Analysis- Lecture note 11/21

*Models Summary 12/21 Transportation Demand Analysis- Lecture note Aggregate time series model Cohort models Aggregate market models Static disaggregate ownership models Static disaggregate type choice models Panel models Demand-supply Demand Supply and demand Level of aggregation Aggregate Disaggregate Dynamic or static model Dynamic Static Long or short run forecasts Short, medium and long (saturation) Medium and long Short, medium and long Long Short and long Data requirements Light Moderate Heavy Socio-demographic-impacts Limited Many possible Impact of license holding No Yes Possible Impact of car cost Fixed and variable None Impact of income Attitudinal variables Hard to include Cohort-specific attitudes can be included Can be included if specific questions in dataset Transportation Demand Analysis- Lecture note 12/21

*Examples of empirical models Transportation Demand Analysis- Lecture note 13/21

(An Aggregate time series model) Transportation Demand Analysis Lecture note The TRRL Models (An Aggregate time series model)

Introduction Transport and Road Research Laboratory, TRRL (UK) Tanner (1958): A saturation point (S) exists where car ownership rates (Ct) stabilize The logistic curve is compatible with the theory of ownership 𝑪 𝒕 = 𝑺 𝟏+ 𝒃 𝒆 − 𝒂 𝑺 𝒕 Transportation Demand Analysis- Lecture note Ct: Car Ownership at time t S: Saturation level t: time a, b: Model parameters g: Car ownership growth rate 14/21

Assumptions The relation of g and Ct is linear 𝑔=𝛼+𝛽 𝐶 𝑡 developed countries The relation of g and Ct is linear 𝑔=𝛼+𝛽 𝐶 𝑡 For a developed country: 𝛼>0 𝛽<0 𝑔=0→𝛼+𝛽𝑆=0 →𝑆=− 𝛼 𝛽 Transportation Demand Analysis- Lecture note 14/21

Parameters Boundary conditions: Therefore: At 𝑡=0→ 𝐶 𝑡 = 𝐶 0 → 𝐶 0 = 𝑆 1+𝑏 →𝑏= 𝑆 𝐶 0 −1 At 𝑡=0→𝑔= 𝑔 0 =𝑎 𝐶 0 𝑆− 𝐶 0 →𝑎= 𝑔 0 𝐶 0 𝑆− 𝐶 0 Transportation Demand Analysis – Car Ownership Models Therefore: 𝐶 𝑡 = 𝑆 1+ 𝑆 𝐶 0 −1 𝑒 𝑔 0 𝐶 0 𝐶 0 −𝑆 𝑆 𝑡

Notes The model is presented for developed countries The pattern may be different for some cities Different levels of saturation may be occurred for different groups of population Different levels of saturation may be occurred along time Recreational vehicles may make noise to this model Household characteristics are not appeared Transportation Demand Analysis – Car Ownership Models

(A Disaggregate model) Transportation Demand Analysis Lecture note The Bates Model (A Disaggregate model)

Introduction A disaggregate car ownership model Uses household information (e.g., household income) derive a probability that a given household will own a number of cars Transportation Demand Analysis – Car Ownership Models

The Model 𝑃 0 1− 𝑃 0 = 𝑎 0 𝐼 − 𝑏 0 𝐷 𝐶 0 𝑃 2 𝑃 1 = 𝑎 1 𝑒 𝑏 1 𝐼𝐷 −𝑐1 𝑃 0 1− 𝑃 0 = 𝑎 0 𝐼 − 𝑏 0 𝐷 𝐶 0 𝑃 2 𝑃 1 = 𝑎 1 𝑒 𝑏 1 𝐼𝐷 −𝑐1 𝑃 0 + 𝑃 1 + 𝑃 2 =1 Pi: the probability that a household will own i car(s) I: Household Income D: Density (Number of Households per Hectare) a, b, c: Parameters of the Model Transportation Demand Analysis – Car Ownership Models

A More Developed Model P(1+): the probability that a household will own one or more cars with corresponding saturation level, S(1+). 𝑃 1 + = 𝑆( 1 + ) 1+𝑒𝑥𝑝(− 𝑎 0 𝐼 𝑡 𝑝 𝑡 −𝑏 0 ) P(2+): the probability that a household will own two or more cars with corresponding saturation level, S(2+). 𝑃 2 + = 𝑆( 2 + ) 1+𝑒𝑥𝑝(− 𝑎 2 − 𝑏 2 𝐼 𝑡 𝑝 𝑡 ) 𝑃 0 =1−𝑃 1 + 𝑃 1 =𝑃 1 + −𝑃 2 + 𝑃 2 =𝑃( 2 + ) Transportation Demand Analysis – Car Ownership Models It: Household income in year t pt: Car price in year t

Transportation Demand Analysis- Lecture note Finish