by
JD Hunt
Department of Civil Engineering
University of Calgary
2500 University Drive NW
Calgary, Alberta
CANADA T2N 1N4
tel: 403-220-8793
fax: 403-282-7026
email: jdhunt@ucalgary.ca
Alan T. Brownlee
City of Edmonton
email: Alan.Brownlee@edmonton.ca
and
Kevin J. Stefan
HBA Specto Incorporated
email: kjs@hbaspecto.com
published in Transportation Research Record volume 1807, and presented at the TRB annual meeting
January 2002
Click here to view the paper in adobe acrobat format
An ongoing topic of interest in urban transportation engineering is the impact of changes in road network capacity upon the amount of vehicle travel made in the urban area. In many cases the debate focuses on the potential increases in vehicle travel occurring with increases in road capacity - the phenomenon of "induced demand". Some studies have also looked at the effects of reductions in roadway capacity, and found that in many of these cases reductions in vehicle travel occur, generally confirming that a relationship exists between roadway capacity and vehicle travel.
This paper provides additional information on this subject, in a North American context.
The City of Calgary, in Alberta, Canada is a thriving major urban centre with a population of over 850,000, and a Downtown employment of over 100,000. Centre Street Bridge is a major road bridge across the Bow River connecting Downtown Calgary to the residential area in the north part of the City. The bridge carries over 34,000 vehicles per day, with heavy peak period flows. In August of 1999 the Centre Street Bridge was closed to car and truck traffic for a period of 14 months for major repairs.
A detailed study was undertaken of changes in weekday traffic, transit and pedestrian flows changes that took place in weekday travel patterns during the closure. This included both analysis of observed count data before and during the closure; and an interview survey with over 1,300 car users of the Centre Street Bridge and the other bridges serving the north side of the Downtown.
his paper summarizes the major findings of this study. Particular emphasis is placed on explaining what happened to the vehicle trips that used the Bridge before the closure.
Disappearing Traffic; Induced Demand; Calgary, Alberta