Keywords: induced travel, land use transport link

Keywords: induced travel, land use transport link

Keywords: induced travel

Claims that roadway investments spur new travel, known as induced demand, and thus fail to relieve traffic congestion have thwarted road development in the United States. Past studies point to a significant induced demand effect. This research employs a path model to causally sort out the links between freeway investments and traffic increases, using data for 24 California freeway projects across 15 years. Traffic increases are explained in terms of both faster travel speeds and land use shifts that occur in response to adding freeway lanes. While the path model confirms the presence of induced travel in both the short and longer run, estimated elasticities are lower than those of earlier studies. This research also reveals significant “induced growth” and “induced investment” effects-real estate development gravitates to improved freeways, and traffic increases spawn road investments over time. Travel-forecasting models are needed that account for these dynamics.

A much more sophisticated methodology to help untangle a complicated problem. The model suggests that it may be possible to build out of congestion without road pricing, although the author speculates that the ultimate urban form may look something like Houston. An interesting side note is the role of density, which exerts a strong influence on the level of induced demand. Unfortunately, since the dataset is from Southern California where truly high densities are rare, the model cannot say too much about roadway expansion in dense areas.

Keywords: transport planning, induced travel, urban form, land use transport link

Keywords: induced travel, transport planning, land use transport link

Keywords: transport modelling, induced travel

Keywords: transport modelling, induced travel

Keywords: transport planning, transport modelling, induced travel

detailed annotation

Keywords: transport planning, congestion pricing, transportation demand management, transit, land use transport link, urban form, induced travel, zoning

detailed annotation

Keywords: transport planning, congestion pricing, transportation demand management, transit, land use transport link, urban form, induced travel, zoning

Keywords: induced travel, land use transport link

Keywords: induced travel, land use transport link

Keywords: induced travel, transport planning

Keywords: transport planning, induced travel, land use transport link

Keywords: induced travel, land use transport link

Keywords: induced travel, land use transport link

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.

This 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.

While I'm not pleased with the results they report, I'm not too surprised. I imagine some of this can be attributed to the fact that it's car-addicted Calgary, but it's still a disappointing result: very little mode shift (<10%). On the upside, the city didn't stop working during the bridge closure; drivers just had to shift their travel times and routes. This isn't very politically acceptable, though; many would feel hard done by if this occurred during a Burrard Bridge lane closure.

Keywords: induced travel, canada, transport modelling, streets, roadspace reallocation

Keywords: induced travel, land use transport link

Keywords: transport planning, induced travel

Keywords: transport planning, land use transport link, induced travel

Keywords: transport planning, land use transport link, induced travel

This paper reviews recent research into the demand inducing effects of new transportation capacity. We begin with a discussion of the basic theoretical background and then review recent research both in the UK and the US. Results of this research show strong evidence that new transportation capacity induces increased travel, both due to short run effects and long run changes in land use development patterns. While this topic has long been debated amongst transportation planners, the fundamental hypothesis and theory has long been apparent in studies of transportation economics and planning that evaluated different issues (e.g. travel time budgets and urban economic development effects). We summarize much of this work and relate the theoretical issues to recent empirical research. We then proceed to examine recent changes in transportation and environmental policy in the US and the UK. The role of the new knowledge of induced travel effects would be expected to lead to changes in the conduct of transportation and environmental policy. Changes in policy and implementation of those policies are still occurring and we provide some suggestions on how to move forward in these areas.

Keywords: induced travel, land use transport link