Traffic congestion is reaching to an extreme level in many metropolitan areas of various developing and developed countries. An efficient public transport can alleviate substantial operational and monetary effects on traffic congestion (Hyman and Mayhew, 2002; Pucher et al. 2007; Vuchic, 1999). In urban transportation areas, traffic congestion is considered one of the major problems (Cervero, 1991; Downs, 1992). During congested and peak hours, public transports can transmit a convincing amount of trips by improving overall transportation capacity and can discharge the surplus demand on crowded road networks.
The average congestion reduction benefits for 85 US cities (Schrank and Lomax, 2005) can be estimated as 42.0 cents per mile or 26.1 cents per km of reduced auto travel (US$, 2005). It was done by considering 18,243 millions of congestion reduction benefits resulting from 43,403 passenger-miles of public transit travel. Here, a one-to-one relationship has been assumed between auto and public transit passenger miles. Using similar assumptions, the congestion reduction benefits of $736 million (Nelson et al. 2006) for public transport in Washington, D.C., can be interpreted as 20.4 cents (US$, 2000) per km of reduced auto travel.
There were 13 studies of transit strikes reviewed by Van Exel and Rietveld (2001) to determine impacts on travel impacts and congestion. The study showed that most travelers switch to car as a driver or passenger. Other travelers switch to alternative modes and some trips are cancelled. Mode shift to car driving was 5 to 50 percent (average 28.6%), mode shift to car lift was 21 to 60 percent (average 29.6%), shift to other modes was 23 to 60 percent (average 39.8%), and trip suppression (stop travelling) was between 5 and 15 percent (average 10.3%). Thus the study showed more dependence on car or taxi rather than transit increases the congestion in road.
There might be some people who would try to get a lift by car during transit strikes, like one group does ridesharing (additional passengers in a vehicle that would be making a trip anyway) and the other group does chauffeuring (additional auto travel specifically to carry a passenger) (Litman, 2006). This analysis suggests that removing public transport can result in increased traffic congestion of about a shift of 20.2 percent of public transport to car driving. However,
Litman’s work also suggests that ex-transit users might also generate extra car travel in the form of chauffeuring trips.
Anlezark et al. (1994) examined mode shift outcomes resulting from the introduction of new Transit Link (express bus services) in Adelaide, Australia. The study showed that about 20 percent of users are new to public transport and of these the highest proportion are formerly car drivers. Mode shift from car drivers was from 8 to 23 percent (average 14.1%), mode shift from car passengers was from 1 to 12 percent (average 5.7%), that results to a congestion reduction of...