Eventbased ATIS: Practical Implementation and Evaluation of Optimized Strategies

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Event-based ATISPractical Implementation
andEvaluation of Optimized Strategies

• R. JayakrishnanJun-Seok OhUniversity of
  California, Irvine

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Contents

• Problem Context
• First Field Test
• Second Field Test
• Effects of Information Reliability on the
  Performance of ATIS
• A Parametric Evaluation Framework for ATIS

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Problem Context
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Motivation

• Is the traveler information always beneficial?
• Why may information do harm?
• What is reliable information?
• Can we provide reliable information?
• How does information reliability influence
  driver's response to information?
• How does information reliability affect to the
  performance of ATIS?

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Overview

• Objectives
• to find optimal routing scheme
• to apply the optimized routing scheme to real
  world
• to construct a comprehensive ATIS evaluation
  framework
• Contents
• Generalization of CMS message
• Network optimization
• Simulation Experiments
• Evaluation of CMS Routing Strategies

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Complexity of CMS Routing

• Point Information
• Information is provided at a certain location.
• It may result in over-reaction.
• Limited Information
• with 3 x 18 characters display
• Not all drivers can follow the information.
• Partial Route Information
• Hard to guide drivers as intended.

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Generalization of CMS message

• CMS Arguments
• Destination (Optional)
• Sub-Path most common argument representing the
  message
• Pc Pc(1), Pc(2),,Pc(k),..,Pc(j)
• Pc sub-path set associated with CMS c
• Pc(k) sub-path k associated with CMS c
• Action and Description
• Take Normal
• Avoid I-5 Minor
  Congestion/Congestion
• Severe Congestion/Almost
  Closed/Closed
• Cause (Optional)

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Types of CMS Message

• Single Descriptive Route Information
• Avoid Path-A
• EX) Katella Congested, Katella 10 minutes
  delay expected
• Prescriptive Route Guidance
• Take Path-A
• EX) ARROWHEAD POND / EXIT BALL
• Route Guidance with Descriptive Information
• Take Path-A, Avoid Path-B
• EX) Stadium / Use Ball / Accident on Katella

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Definitions

• Compliance Rate
• A ratio of drivers who complied among all drivers
  whose routes were different from those suggested.
• Diversion Rate
• Actual observed change in flow split ratio.
• Credibility
• Driver's level of trust on information devices.
• Reliability
• Accuracy of Information affecting driver's
  credibility.

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Static Optimization for CMS Routing

• CNIS message is displayed at a certain location,
  so for a single CMS the problem becomes a
  single-origin multiple-destination problem.
• While assuming that only informed drivers change
  their routes, the optimal solution can be
  obtained by solving the single origin problem.
• A guidance indicator is introduced to evaluate
  sub-paths on the network, affecting driver's
  perceived cost.
• The cost of a sub-path to test is multiplied by
  the guidance indicator, and the indicator is
  found minimizing total system cost while demand
  is assigned under user equilibrium behavior.

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Interaction between information provider and
drivers
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