Traffic Calming—The First Wave
For several decades there have been efforts to use roadway modifications, such as humps and chicanes, to control motor vehicle speeds on streets whose primary roles are non-traffic ones (Hass-Klau 1990). Such traffic calming began in north-west Europe and by now is familiar almost everywhere.
Early traffic calming tended to focus on streets at the lowest levels of the roadway hierarchy to reinforce the primacy of access and pedestrian activity at that level. More recently, adaptations of traffic calming techniques have been applied to some streets at higher levels of the hierarchy, such as short stretches of shopping streets and the main streets of towns. An early Dutch traffic calming innovation, the Woonerf or “home zone”, involved a complete redesign of urban residential streets to make it clear to motorists that they were guests in a home environment. This was a precursor to the more ambitious shared space experiments.
Tempo 30 Zones (Or “Twenty’s Plenty”)
A variation on traffic calming is to simply signpost very low speed limits, notably 30 km/h (or 20 miles/h). Many European cities now have extensive Tempo 30 zones (Figure 1). Graz in Austria has been a pioneer, with a blanket 30 km/h speed limit over much of the city. Only major roads allow higher speeds of 50 km/h or more. Sweden’s “Vision Zero”, which aims to eliminate road deaths and minimise the effects of the “foreseeable crashes” between pedestrians and motor vehicles, has prompted more Tempo 30 zones in that country.
Shared Space (Or “Naked Streets”)
The shared space approach to streets emerged in the 1990s, pioneered by the late Hans Monderman in towns across the northern region of the Netherlands. Sometimes called “naked streets”, this approach is also seen as a second generation of traffic calming that has been spreading rapidly with trials underway in many countries. Shared space completely overturns the idea that urban road safety depends on predictability and on clearly defining who has the right of way (Hamilton-Baillie 2008). Shared space designs often remove most traffic lights, signs and kerbs. No particular user or movement has automatic right of way. This forces road users (car or truck drivers, bicycle users and pedestrians alike) to proceed cautiously and to negotiate their way forward, mostly through eye contact. Australian innovator, David Engwicht (2006), calls this “safety through intrigue and uncertainty”. If this is difficult to imagine, then the videos at http://www.youtube.com/user/Sharedspace will help.
Low speeds are both a consequence of and a necessity for this social mode of negotiated motion. In high-speed traffic the human mind is not capable of negotiating with other road users through eye contact. We can only do this at or below about 30km/h. Both crash incidence and the probability of death or injury, even for pedestrians, are very low at these speeds (Shared Space project 2005). Trials have included main streets and intersections in town centres. Surprisingly, travel times hardly suffer because, although top speeds between junctions are much lower, there is much less stopping at intersections.
Even though shared space includes motor vehicles, they become very much part of the public realm at low speeds. Monderman made clear that shared space design is only for the parts of the network that can be designated as public realm. His vision of an expanded public realm includes many surprisingly busy streets. However, it does not include those major arterial roads on which high speeds remain important. These remain traffic space.
Accidental Shared Space
The informal emergence of shared space street dynamics can be seen when pedestrians and/or slow vehicles dominate a street space, leaving motorists little choice but to proceed on a negotiated and cautious basis. This is common in inner urban streets of many developing countries (Figure 2). It can be seen also on the narrow streets of Singapore’s Little India area. Such “chaos” is of course widely lamented, with pedestrians and other road users blamed for indiscipline. Moreover, at times of low pedestrian activity, traffic speeds do rise and crash risk and severity can become very high. However, the imposition of traffic-focused design in such places would often be a mistake. A better option for these streets might be shared space by design rather than by accident.
Bicycle Boulevards/Slow Streets Network
Traffic-calmed “bicycle streets” on which bicycles have clear priority over motor vehicles are common in German cities, among others (Pucher and Buehler 2008). A number of North American cities, notably Berkeley, California, have successfully used bicycle boulevards to enhance their network of safe, low-stress routes for bicycle users. Bicycles enjoy relatively uninterrupted journeys along these streets, whereas motor vehicles often face detours.
Surprisingly, it is also possible to create public realm and local access functions on very busy roadways that move a large volume of fast-moving traffic. Multi-way boulevards are one way to do this. The Boulevard Book by Jacobs et al. (2002) highlights their potential and provides guidance on design. The trick this time is to create slow spaces at the edges
Some of the most elegant and successful streets in the world, such as many of the avenues in Paris, are multi-way boulevards. They are typically grand streets that have a central zone that is primarily traffic space. Then there is a tree-lined landscaped zone with walkways. This wide median separates the main traffic lanes from a smaller roadway next to another footway and the building line (Figures 3 and 4). In the best boulevards, this side-access street forms the low-speed public realm where traffic, bicycles and pedestrians can share the space safely. The authors argue that well-designed multi-way boulevards, such as Avenue Montaigne in Paris or the Passeig de Gracia in Barcelona, have good safety records, and the traffic lanes work better than equivalent space on conventional roadways. Many countries in Asia, including India, China, Vietnam and Indonesia, also have a tradition of multi-way boulevards. Some, such as CG Road in Ahmedabad, already work well while others could benefit from an effort to ensure low traffic speeds in the service lanes in order to include these lanes and their adjacent medians as part of the public realm.
“Road diets” is another innovation that allows public realm to be created with minimal impact on the utility of traffic space. As you may guess from the name, arterial roads have their traffic lanes reduced (and sometimes narrowed). However, a centre turning lane or turning bays are added, often with medians and an expansion of pedestrian and cycling space as well. In many situations, all this can be done without a loss of vehicle capacity.
Department for Transport (DfT) U.K. March 2007. Manual for Streets http://www.dft.gov.uk/pgr/sustainable/ manforstreets
Engwicht, D. 2006. Int
rigue and Uncertainty: Towards New Traffic Taming Tools. Creative Communities International (This is an e-book which can be downloaded via http://www.lesstraffic.com/index.htm).
Hamilton-Bailie, B. 2008. Shared space: Reconciling people, places, and traffic. Built Environment 34 (2), 161- 181.
Hass-Klau, C. 1990. The Pedestrian and City Traffic. Belhaven Press, London.
Jacobs, A.B., Macdonald, E. and Rofé, Y. 2002. The Boulevard Book: History, Evolution, Design of Multiway Boulevards. MIT Press, Cambridge, MA.
Patton, J.W. 2007. A pedestrian world: Competing rationalities and the calculation of transportation change. Environment and Planning A, 39(4), 928 – 944.
Pucher, J. and Buehler, R. 2008. Making cycling irresistible: Lessons from the Netherlands, Denmark and Germany. Transport Reviews 28 (4), 495-528. http:// dx.doi.org/10.1080/01441640701806612
Shared Space project. June 2005. Room for Everyone: A New Vision for Public Spaces. Report of the European Union Iterreg IIIB project ‘Shared Space’. Available via http://www.shared-space.org
Shared Space project. Oct. 2008. Final Evaluation and Results: It Takes Shared Space to Create Shared Understanding. Report of the European Union Iterreg IIIB project ‘Shared Space’. Available via http://www.sharedspace. org
Svensson, Å. ed. 2004. Arterial Streets for People. Report of the ARTISTS Project (Arterial Streets Towards Sustainability). Available via http://www.eukn.org/urbanmatrix/ themes/urban_policy/urban_environment/La
Paul Barter is an Assistant Professor in the Lee Kuan Yew School of Public Policy, National University of Singapore where he teaches infrastructure policy, urban policy, transport policy and an introduction to public policy. He has published studies of transport policy in Kuala Lumpur and Singapore. His current research interests are in innovation in transport demand management, public transport regulation, and contested priorities in urban transport policy.
This article appeared in the May number of JOURNEYS, a new LTA Academy publication (The Land Transport Authority of Singapore) and is reproduced here with their kind permission and that of the author. We felt that this is such a good survey it deserves wide circulation and international, and we are pleased to provide it here. To view the original article and illustrations, you are invited to click here.