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

System user

Mode or technology of travel

Stake holdersIntermodal connections

for transfers

Infrastructure that allows travel to occur

Supply Analysis:Evaluate the characteristics

of infrastructure

From ROW to service frequency – anything that is needed to provide transportation to the user

(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

Two perspectives

The user User optimal

The (system) operator System optimalUser 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.

(See p.387-390 for the explanations of the 4 “linkages” shown.)

Characterization of a transportation system: We can analyze the characteristics of the supply from different perspectives.

Performance

Impacts Costs

e.g. Travel times, frequency of service, safety, and reliability

e.g. Environmental and social/cultural

e.g. Capital cost, operation cost, maintenance/rehab cost

Focus of this lecture

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 pollutionFor 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.