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Lec 17, Supply Analysis Part 1: Role of supply analysis (ch7.1) and Analysis of system performance (ch7.2). The role of performance analysis in transportation planning Performance measures used Performance analysis concepts
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Lec 17, Supply Analysis Part 1: Role of supply analysis (ch7.1) and Analysis of system performance (ch7.2) • The role of performance analysis in transportation planning • Performance measures used • Performance analysis concepts (The topics described in 7.2 are the major topics of CEEn 562 Traffic Engineering & CEEn Traffic Simulation and Signal Optimization. Hence we touch only the basics, or general concepts, in this class.)
Transportation system components & supply analysis Supply Analysis: Evaluate the characteristics of infrastructure System user Mode or technology of travel From ROW to service frequency – anything that is needed to provide transportation to the user Infrastructure that allows travel to occur Intermodal connections for transfers Stake holders (5 major components of the transportation system)
The role of supply analysis in TP • Developing and managing the supply of transportation is a primary focus of an effective transportation planning process. Analysis results are used at different levels of decision making • Metropolitan-level network analysis for strategic investment • Operational or tactical planning • Scheduling of transportation services
Supply analysis in transportation planning (See p.387-390 for the explanations of the 4 “linkages” shown.) • Two perspectives • The user User optimal • The (system) operator System optimal User optimal solutions are not always system optimal, e.g., Everyone wants to drive because it is convenient (user optimal), but congestion occurs and air is polluted more than necessary (System is not at optimum). • In order to estimate system impacts and costs, one must first estimate system performance.
Characterization of a transportation system: We can analyze the characteristics of the supply from different perspectives. Performance e.g. Travel times, frequency of service, safety, and reliability Focus of this lecture Costs Impacts e.g. Capital cost, operation cost, maintenance/rehab cost e.g. Environmental and social/cultural
Network representation of the real system QRS II representation of the network
Network characteristics, typical ones for highways/streets: • Speed: Avg. running speed, avg. travel speed, space mean speed, time mean speed, free flow speed • Volume or flow rate • Density, vpm or vpk • Capacity • Level of service • Fuel use • Air pollution For uninterrupted flow, major characteristics are related. (Do you remember what you did in CE361?)
7.2.2 Performance analysis concepts • Time-space diagrams (micro) • Queuing theory (macro) • Fluid-flow approximation (macro) • Simulation (micro) • Mathematical programming (macro) These are covered in CE561, CE562, and CE662.
Simulation example: CORSIM • Simulating an incident. CORSIM can simulate multiple time periods.