01 general introduction of travel demand analysis dr binh

October 5, 2016 Transportation Planning and Policy General introduction of travel demand analysis Contents of today’s class    Introduction Process of travel demand forecast Travel demand models Introduction Characteristics of travel     Each consumer or company makes a complex set of decisions relating the movement based on his/her needs and environment These include purpose, frequency, timing, destination, and mode of trips Further, these decisions must be analyzed in the context of the intertemporal behavior of the consumer and company, and long-run decisions on home, workplace, office location and on automobile ownership Thus, travel is a concomitant of various consumption and supply activities What is the travel demand?   Travel demand is defined as the amount of movements of individuals and/or goods There are various units of travel demand, for example,     Total number of passengers during a specific period (ex Passenger per day) Total travel distance (ex Passenger kilometer) The number of goods transported by a specific transportation mode The number of passengers traveling from one place to other place What is the travel demand analysis?   Travel demand analysis examines the characteristics of travel demand Travel demand analysis is not transportation planning; it can only support planning, and in a few cases it may have the most important role in the process Travel demand forecast  Travel demand analysis can contribute to the travel demand forecast Travel demand Policy A ? Past trend Year Travel demand forecast in a transportation planning Travel demand forecast Philosophical background of travel demand analysis  Empiricism (Chủ nghĩa kinh nghiệm)     Empiricism is a theory of knowledge which emphasizes those aspects of scientific knowledge that are closely related to evidence, especially as formed through deliberate experimental arrangements It is a fundamental requirement of scientific method that all hypotheses and theories must be tested against observations of the natural world, rather than resting solely on a priori reasoning, intuition, or revelation Scientific laws describe the general patterns of our experiences To explain the phenomena in a scientific way means to show an example of scientific laws We can forecast the future of the same phenomena by knowing the laws Travel demand analysis as a part of social science  Positivism (chủ nghĩa thực chứng)    Positivism is a philosophy that states that the only authentic knowledge is scientific knowledge, and that such knowledge can only come from positive affirmation of theories through strict scientific method The above idea can be applied to the human psychology and social life Then, these discipline can be formulated as the “Social Science” Once the knowledge of social science is established, it is possible to control and regulate the individual behavior and social collective movement Like the natural scientists who contribute to solving the practical engineering problems, the social scientists can also recognize the social problems and conflicts based on the social scientific knowledge and solve them one by one 10 Travel Demand Analysis/Forecast Model Models: Simplified representations of reality Why are models used in transport planning? (1) To predict future conditions in the absence of policy intervention Ex.) We can assess how much conditions will deteriorate (2) To predict future conditions on the assumption that the specified policies are implemented Ex.) We can assess the benefit (3) To test the performance of a given policy Ex.) We can check its “robustness” 33 What is a model? INPUT FUNCTIONS OUTPUT 34 Structure of travel demand model rong, congestion, GDP GRDP dan so Socioeconomic variables Level-ofService (LOS) variables Other variables Travel demand models Travel demand 35 Desirable features of a model (1) Accuracy and precision  What level of accuracy is really required is determined by the context in which the model is used (2) Economy in data and computing resources  What data already exist and at what cost additional data could be provided? (3) Ability to produce relevant indicators at appropriate level of disaggregation (4) Ability to represent relevant processes and interactions  The model should include a representation of any processes which may be influenced by the policy measures being tested (5) Appropriate geographical spread  The model should include the whole area in which the effect of a policy might be felt (6) Others  Transparent model, user-friendly model 36 Fundamental concept (1) Optimization in behavior    Travelers make their decisions by maximizing or minimizing something Ex.) Utility maximization: classical economic theory Behavior is a result of individual’s attempting to maximize their net gain, or minimize their net loss In the transport planning theory, the concept of “minimization of the generalized cost” is sometimes used 37 Fundamental concept (2) Aggregation of individual behavior  Transport system is the result of decisions by many individuals  Most transport planning are concerned with abstract totals: total flow, average speed, etc  Although we are concerned with aggregates of people, their behavior can probably best be understood by considering the behavior of individual travelers 38 Types of travel demand models (1)  Models based on natural scientific theory    Energy minimization Entropy maximization Finite element method, etc…  Models based on social scientific theory  Psychological theory    Attitude Cultural, religious custom Economic theory  Utility maximization under the constraints 39 Types of travel demand models (2)  Passenger transportation    An individual judges where and when to go, which mode to use, and how frequently to travel The decision-maker is a single individual or several individuals in a group Private transportation vs public transportation  Goods transportation     An individual and/or companies make a decision Many decision-makers are involved in a single good transportation Goods themselves not make any decision Shape, unit, and characteristics may be changed through the transportation chain 40 Types of travel demand models (3) Aggregate model vs dis-aggregate model  Aggregate model (ex modal share)   Dis-aggregate model (ex Individual choice of travel mode)    The model analyzes the percentage of total population choosing a specific transportation mode An individual choose a specific travel model with some percentage of probability If we assume a representative individual in a given population, we may derive the specific alternative’s share from the representative-individual’s probability of choosing that alternative We sometimes assume a representative individual by zone or by socio-demographic 41 Types of travel demand models (4)  Static model   The model assumes that the travel behavior is stable during a given period It does not consider explicitly that the one travel behavior at a time influences the other travel behavior at a later time  Dynamic model    The model describes the time-series variation of travel behavior The differential equation approach is applicable to the dynamic model However, as the dynamic change of travel behavior is too complex, the microsimulation approach is often used 42 AVENUE (developed by Professor Masao Kuwahara, University of Tokyo): Traffic flow and parking simulation around a shopping mall 43 Traffic microsimulation models  Traffic microsimulation software has become increasingly popular as a traffic analysis tool used in transportation analyses   One reason for this increase is the need to model and analyze the operation of complex transportation systems under congested conditions Examples: NETSIM (FHWA, US), PARAMICS (DoT, UK), AIMSUM (Polytechnic University of Catalunya, Spain) 44 Types of travel demand models (5)  Deterministic model   The model assumes that an individual makes a decision with the perfect information The analyst is assumed to be able to observe the data without error and to collect the perfect data covering all factors which affect the traveler’s behavior  Stochastic model     The model emphasizes the variability in individual’s perceptions of information The travelers may not have perfect information about their travel environment The observed data may also include some errors Unobserved factor may influence the traveler’s behavior 45 Types of travel demand models (6)  Single market model    The traditional travel demand model covers only transportation market The factor relating to the other market than transportation market is regarded as the exogenous variables The single-market model assumes the partial equilibrium  Multi-market model    The model takes the interaction among markets into consideration Transportation market is closely related with the other market including land market, housing market, labor market The multi-market model assumes the general equilibrium 46 Types of travel demand models (7)  Simultaneous model   The model deals with the individual travel behavior as the simultaneous equation models An individual may decide the series of travel behaviors at the same time, including whether to travel, where and when to go, which mode to use, how often to travel, and with whom to travel  Sequential model    The model divides the travel behaviors into several steps and computes the demand step by step The simultaneous model requires the huge computation time Furthermore, actually, the individual often makes his/her decisions sequentially rather than simultaneously 47 ...Contents of today’s class    Introduction Process of travel demand forecast Travel demand models Introduction Characteristics of travel     Each consumer or company makes a complex set of decisions... The number of passengers traveling from one place to other place What is the travel demand analysis?   Travel demand analysis examines the characteristics of travel demand Travel demand analysis... process Travel demand forecast  Travel demand analysis can contribute to the travel demand forecast Travel demand Policy A ? Past trend Year Travel demand forecast in a transportation planning Travel