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Title:

Cronbach’s α as Performance Measure to Assess Link-level Reliability

Accession Number:

01555325

Record Type:

Component

Availability:

Transportation Research Board Business Office

500 Fifth Street, NW
Washington, DC 20001 United States

Abstract:

Travel time reliability is commonly used in reference to the level of consistency in transportation service for a trip, corridor, mode or route. Traditional indicators of reliability are Buffer Time Index (BTI) and Planning Time Index (PTI). Since these indices are evaluated for a single arrayed data set, they only measure the reliability in one dimension. However, travel time variation due to congestion depends on time-of-the-day, day-of-the-week, and week-of-the-year (involves multiple factors or dimensions). The one dimensional measures, while addressing the reliability of a link, confine themselves to the trips of a given time-of-the-day and day-of-the-week. Overall comparison of reliability of two links is therefore not possible. To address this limitation, this research proposes and demonstrates the use of Cronbach’s α (a two-dimensional measure) as a performance measure complementing the traditional indicators to assess link-level reliability (on the basis of travel times observed on the links). INRIX travel time data for Charlotte, Mecklenburg County, North Carolina for the year 2009, comprising about 300 Traffic Message Channel (TMC) codes (links), were used in the current research to demonstrate the methodology. The most reliable travel time values for trips on each link were determined based on their level of reliability while also categorizing the link performance into different levels of reliability using the scores that are evaluated in this research.

Supplemental Notes:

This paper was sponsored by TRB committee ABJ30 Urban Transportation Data and Information Systems.

Monograph Accession #:

01550057

Report/Paper Numbers:

15-5369

Language:

English

Corporate Authors:

Transportation Research Board

500 Fifth Street, NW
Washington, DC 20001 United States

Authors:

Puvvala, Ravi K
Pulugurtha, Srinivas S
Duddu, Venkata R

Pagination:

15p

Publication Date:

2015

Conference:

Transportation Research Board 94th Annual Meeting

Location: Washington DC, United States
Date: 2015-1-11 to 2015-1-15
Sponsors: Transportation Research Board

Media Type:

Digital/other

Features:

Figures; References; Tables

Geographic Terms:

Charlotte (North Carolina)

Subject Areas:

Data and Information Technology; Highways; I72: Traffic and Transport Planning

Source Data:

Transportation Research Board Annual Meeting 2015 Paper #15-5369

Files:

TRIS, TRB, ATRI

Created Date:

Dec 30 2014 1:48PM