Theory

• Pre-analysis phase


  Identification of problems, defining goals, operationalising objectives
• The major increase in computing power made it possible to analyse problems with a significantly larger scale and level of detail
• Urban transport modelling system

  Four stages: Trip generation, Trip distribution, Modal split, Traffic assignment
• Generation of solutions for testing

  Can be achieved in various ways, including tapping experience and creativity of local transport planners, construction of design models
• Role of the model in transport planning

  Contributes to the key steps of a decision-making framework
• Analytical models


  Attempt to replicate the system of interest and its behavior using mathematical equations
• Model


  A representation of a part of the real world concentrating on important elements for analysis
• Models are necessary in transport planning due to the impossibility of conducting experiments on existing or non-existing infrastructure and transport modes
• Planning phases

  Pre-analysis phase, Technical analysis phase, Post-analysis phase
• Construction of an analytical model

  Specifying, estimating, calibrating parameters, validating performance
• Technical analysis phase

  Predicting traffic flow, using forecasting techniques, predicting future distribution of houses, employment, shops, and land uses
• Post-analysis phase

  Evaluation of alternatives, implementation of chosen alternative, monitoring system
• Models are subject to bias when used for forecasting
• A theoretical framework was developed, compatible with economic theory, providing a justification and clarification of methods that were originally proposed on practical grounds
• Transport systems are composed of a complex set of relationships between demand, service locations, and supporting networks
• Transport system consists of three interdependent layers: Travel patterns, Transport services, Traffic services
• Transport systems evolve within a complex set of relationships between transport supply and demand
• Generation of solutions for testing

  Tap experience and creativity of local transport planners, construct a large-scale design model using optimisation techniques
• An economic system with activities in different areas generates movements supported by the transport system
• Testing the model and solution

  Test model performance under different scenarios to confirm reasonableness
• Transport demand is the expression of transport needs in terms of passengers, volume, or mass per unit of time and space
• Evaluation of solutions and recommendation

  Operational, economic, financial, and social assessment of alternative courses of action based on model indicators
• Transport is a service that must be utilized immediately and cannot be stored
• Passenger-km and ton-km are common measures expressing realized passenger and freight transport demand respectively
• Demand for travel is dependent on the trip to be made, available modes, and individuals making the trips
• Model construction


  Select the simplest modelling approach possible, specify the model, estimate and calibrate parameters, validate performance
• Transport systems are mainly dependent on the commercial environment for attributes such as transport costs, capacity, efficiency, reliability, and speed
• Forecasting future values of planning variables

  Necessary to test proposed solutions or schemes
• Transport supply is the capacity of transport infrastructures and modes over a geographically defined system for a specific period
• Traffic services

  Enable the movement of transport modes through physical infrastructure and management and operations of the infrastructure (incl. pricing policies)
• Classic four-stage model

  Trip generation model estimating the total number of trips generated by or attracted to each zone of the study area

  2. Trip distribution allocating trips to destinations

  3. Modal split modelling the choice of mode

  4. Assignment of trips by each mode to their corresponding networks
• Demand for travel is actually a derived demand, as it is generated by the desire to join in activities, and generally not by the desire just to travel. The transport system provides a physical connection between activities
• Macroscopic flow models


  Flow units are assumed to behave in some collective fashion
• If demand is higher than supply


  Prices would rise due to "bidding up" of the customers, stimulating an increase in supply and a decrease in demand, driving the market to the equilibrium point
• Land use impact assessment models

  Focus on changes to new land use facilities and use a rudimentary description of the transport system serving that facility in predicting its impacts on the surrounding region
• Limitations of trip distribution models

  • Constant trip lengths
  • Use of automobile travel times only to represent 'distance'
  • Limited effect of socio-economic-cultural factors
  • Feedback problems
• Dense network models


  Simulate flows in small-scale networks where the level of flow on each link can vary in response to changes in the traffic control system and traffic congestion levels, focusing on short time periods (e.g., a peak hour)
• Supply in transport

  System performance, including travel times, headways, and capacities provided by the transport system given a certain capital investment, operating strategy, and demand level
• Microscopic simulation


  Assessment of individual vehicle or driver performance at an intersection or along a link
• Characteristics of travel

  • Time
  • Monetary cost
  • Inconvenience
  • Discomfort