Keywords: streets, history, urban politics, street design, roadspace reallocation, zoning

Keywords: transport planning, streets, roadspace reallocation

Reallocating roadspace from general traffic, to improve conditions for pedestrians or cyclists or buses or on-street light rail or other high-occupancy vehicles, is often predicted to cause major traffic problems on neighbouring streets. This paper reports on two phases of research, resulting in the examination of over 70 case studies of roadspace reallocation from eleven countries, and the collation of opinions from over 200 transport professionals worldwide. The findings suggest that predictions of traffic problems are often unnecessarily alarmist, and that, given appropriate local circumstances, significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed. Follow-up work has also highlighted the importance of managing how schemes are perceived by the public and reported in the media, with various lessons for avoiding problems. Finally, the findings highlight that well-designed schemes to reallocate roadspace can often contribute to a multiplicity of different policy aims and objectives.

Keywords: transport planning, streets, roadspace reallocation

Keywords: transport modelling, roadspace reallocation

Keywords: transport modelling, transport planning, roadspace reallocation

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