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Title:

Car Occupancy in Travel Modeling: Insights into Carpooling Propensity and Limits

Accession Number:

01663930

Record Type:

Component

Abstract:

Carpooling behavior is central to many transportation planning studies and proposed travel demand management strategies. Increasing vehicle occupancy has the potential to reduce congestion and emissions by increasing the efficiency of roadway use. Traditionally, travel demand models assume an unlimited elasticity for HOV and SOV mode shares with respect to travel time and cost. Limits to traveler’s ability or willingness to carpool is primarily captured through alternative-specific constants on HOV modes. On one hand, this framework neglects to account for practical limits on carpooling, such the difficulty of finding carpooling partners. On the other hand, a substantial portion of HOV trips are intrinsically carpools by nature (e.g. joint travel). In reality, both of these groups are insensitive to policies that differentiate HOV and SOV modes by travel time or cost. This paper presents a framework to account for carpooling propensity and limits, based on a stated preference survey conducted in Toronto in 2016. This approach breaks down the traditional mode choice model into a two-part process, first assigning each trip to be either flexible between SOV and HOV modes (as in a traditional mode choice model), or captive to either SOV or HOV, if an auto mode is ultimately chosen. This is followed by the application of a modified mode choice model, with corresponding availability rules. This two-part model is iteratively calibrated to match traditional mode choice shares and meet reasonable limits of carpooling behavior.

Supplemental Notes:

This paper was sponsored by TRB committee ADB10 Standing Committee on Traveler Behavior and Values.

Report/Paper Numbers:

18-04676

Language:

English

Authors:

Bernardo, Chrissy
Vovsha, Peter

Pagination:

17p

Publication Date:

2018

Conference:

Transportation Research Board 97th Annual Meeting

Location: Washington DC, United States
Date: 2018-1-7 to 2018-1-11
Sponsors: Transportation Research Board

Media Type:

Digital/other

Features:

Figures; References; Tables

Geographic Terms:

Toronto (Canada)

Subject Areas:

Highways; Planning and Forecasting

Source Data:

Transportation Research Board Annual Meeting 2018 Paper #18-04676

Files:

TRIS, TRB, ATRI

Created Date:

Jan 8 2018 11:09AM