22-29 Zacharias Feature

ITE JOURNAL / AUGUST 1999 PEDESTRIAN ZONES HAVE become a familiar feature in the central areas of European cities. Private cars are always excluded from these zones, while delivery vehicles are permitted during off-peak hours. Bicycles and taxis are typically relegated to a circumferential service road. Some have argued that such rigid traffic separation contributes to economic and environmental disparity between the pedestrian zone and its surroundings. The concentration of high-value retailing, services and pedestrians within the zone contrasts with low values and heavy car traffic at the periphery. Traffic-calming experiments during the 1970s and 1980s demonstrated that environmental design could reduce both the volume and the environmental impact of cars in local areas. These results have led to speculation about how a controlled mix of traffic modes might be made to lessen these central-area contrasts. The role of the bicycle in particular has not been addressed in pedestrian zone planning. The bicycle is typically treated as a vehicle even in those cities where its use is encouraged. However, since environmental design cannot be used to exclude cyclists from pedestrian areas, planners have to rely on cyclist adherence to regulation, a dubious proposition in many cities. The Netherlands has consistently embraced the principles of traffic separation while promoting use of the bicycle. Pedestrianized core areas and an extensive system of separate bikeways are found in all major towns and cities. Bicycles are routinely used for all kinds of intra-urban trips and are found not only on bicycle pathways but on all other streets as well. The extensive pedestrian zones, some exceeding a 30-minute walk across the diameter, make the bicycle more attractive than pedestrian or public transportation alternatives. The bicycle offers significant time saving, relative safety and convenience.1 The pedestrian zones provide cyclists with alternate routes that are often illegal but are nevertheless used on a regular basis. Authorities tolerate cyclist use of these pedestrian paths, as long as it does not contribute to pedestrian discomfort or accidents. Some Dutch observers argue that such a liberal approach works best since the level of cyclist use is largely self-regulating. According to the selfregulation theory, cyclists take responsibility for collision avoidance and pedal through pedestrianized zones if pedestrian traffic volumes allow them to do so comfortably and safely. This de facto mixing of modes merits study for several reasons. If such systems can be made to work safely and efficiently, they can solve many planning problems. The major issues in addition to level of service are comfort, convenience, safety and attractiveness.2 While engineers have generally supported traffic separation as safer than mixing, not all agree with this view, citing the persistent accident rates at intersections of pedestrian and bicycle pathways with vehicular routes.3 The self-regulating theory also requires empirical verification. In particular, we need to understand how pedestrian volume flow level impacts on bicycle volume flow. Separated bicycle pathways take space on the street, usually the width of a traffic lane in each direction. In Amsterdam as in many other cities in Europe and North America, implementing such an arrangement with separated footpaths means a drastic reduction in the space allocated to vehicles, if not their elimination from the street. One of the major questions raised by such designs are their carrying capacity The Amsterdam Experiment in Mixing Pedestrians, Trams and Bicycles