Modifying traffic behaviour through legible urban design.
Ben Hamilton-Baillie
Abstract
Traffic engineering and urban design have developed as separate professional disciplines. This paper looks at the historical basis for traffic engineering in towns and cities and its influence on relationships between traffic and places, between the highway and the public realm. It draws on ideas and experiments in mainland Europe that challenge the traditional separation of social activities and vehicular movement, manifested through Dutch woonerf design principles and home zones. The paper explores some recent developments in this tradition that use legibility and an enhanced sense of place as the cornerstone of traffic engineering, to place a clear distinction between the regulated world of the highway and the culturally defined public realm. Using contextual design and an awareness of history, landscape and architecture, the new approach to shared space in cities combines clear gateways, lower traffic speeds, the use of eye contact with the removal of road markings, signage and the conventional regulations of the state. The paper concludes with some suggestions for how such an approach might be applied in Bristol or Bath, placing legibility at the heart of an approach to safety and urban regeneration.

Introduction: Traffic Engineering and the Public Realm
Step off the bus or the train on arrival in any town or city. The backdrop to your first impression will be determined by the history, landscape, topography and the architecture of place. Buildings, and their interrelationships, will be inspiring or depressing, depending on the creative efforts of man and nature. We know we are in Bath, Bolton or Bristol by a unique, complex mixture of natural and artificial landmarks and symbols that provide the data for our mental maps and our memories.
Yet the foreground to our experience of cities is very different. It is likely to have been fashioned neither by natural processes, nor by the peculiarities and idiosyncrasies of architecture or the design professions. The immediate, close-up environment of almost all our cities are determined by kerbs, asphalt, road markings, bollards, traffic signals, barriers and signs. We will negotiate our journey into and through the city amidst a landscape fashioned by traffic engineering. The rules that govern this landscape have little in common with the special cultural history and values that will have shaped the architecture and the unique signature of place. Indeed, the overarching principle governing the foreground has its roots in the desire for consistency, conformity and predictability. Traffic engineering seeks uniformity and unambiguous clarity, demanding the same standards, dimensions and hardware whether the backdrop is Fort William or St. Austell.
We quickly learn to accept and blank out the foreground, and to accept the presence of traffic engineering in cities as a tiresome, but necessary, component in the urban language. Transport, and its attendant infrastructure, is such an integral and vital part of the urban fabric that it is impossible to imagine the shape of a place without the transport element. For most of us the map of London IS the Tube Map, Venice is its canals, Paris is remembered by its boulevards, and
Los Angeles is defined by its freeways. Most places have less memorable arteries. Our walk from the station will probably take us down roads and streets with a familiar pattern. A change in level at the kerb will signal the space set aside for pedestrian activity and social interaction from the carriageway. Parallel lines of parked cars will reinforce this separation. The carriageway will probably be marked by a central white dividing line, and painted lines will define hierarchies and priorities at intersections. Road lighting will provide a predetermined level of background illumination. Lights and markings will indicate where pedestrians should cross the road. The
Beatles “Abbey Road” cover bequeathed us a backdrop of a suburban road so recognizable and typical as to be eternally familiar. We know where we drive, where we are supposed to walk, and where we cross the road. It is sometimes difficult to imagine that these rules could be different.
This paper reflects on how the relationship between traffic, people and places might be otherwise. I hope to suggest that a new set of principles to define the relationship of traffic engineering and urban design might offer possibilities for reconciling the competing and conflicting demands for safe, efficient movement with the quality and legibility of the built environment. My interest stems from two sources. Firstly I have long been intrigued by Dutch,
Danish, German and Swedish practice in this traffic management and street design. Secondly, whilst spending a year in a major design school in the USA, the absence of traffic engineers amongst the architects, urban planners, urban designers, landscape architects, civil and structural engineers and the other members of the design professions puzzled me. The traffic engineers were trained elsewhere, far from the design schools. The otherwise well-stocked libraries contained little reference to traffic engineering, and I could find no comprehensive history of the subject. The distance between traffic engineering and urban design seems to be reflected in universities everywhere, and the disciplines appear to have entirely disconnected sources and starting points. And yet in American cities I was struck by how much of the space between buildings was defined and determined by traffic engineering and not by the design professions. In
Houston, Texas, and in Minneapolis, over 70% of the urban space is made up of streets and car parks. The architecture and urban design is relegated to an insignificant minority.

Figure 1. Houston, Texas.
Even in the UK, 30-40% of public space lies in the realm of the traffic engineer, outside our general understanding of the “public realm”. If we wish to understand how cities might become more legible, more coherent, and more liveable, it would seem sensible to understand more fully how this dichotomy has arisen, and whether there might be common ground between the worlds of the design professions and the traffic engineers.
The historical background
Few have heard of Eugene Henard. Yet, as the father of modern traffic engineering, his work could be said to have had more influence on modern cities than many of the great architects and planners. Working for the Musée Sociale in Paris at the end of the nineteenth century, Henard drew some remarkable sketches for traffic circulation in the same of rationalisation and social reform. He is credited 1 with the invention of the traffic roundabout in 1877, and his proposals for junction designs, left-hand turn lanes and advanced stop-lines would not look out of place in the modern traffic engineering handbook. Look carefully at his sketches, and all his vehicles are horse-drawn; his work predates the automobile. One sketch proposal for a boulevard intersection illustrates the novel concepts of a gyratory roundabout with a consistent direction of clockwise travel, pedestrian underpasses, traffic islands, and a split-level traffic and pedestrian concourse. It is the direct forerunner of the “bear pit” of St. James Barton roundabout in Bristol, and countless other examples of 1960’s and 1970’s traffic rationalisation. It is always satisfying to be able to blame the French for our current woes...
Figure 2: Eugene Henard. Proposed Junction. Paris 1895
1 See Wolf, Peter. Eugene Henard and the Beginning of Urbanism in Paris, 1900-1914 (1968).

Few of Henard’s ideas were implemented during his lifetime, but his work was taken up by a new generation of traffic engineers and planners across the developed world, notably in Britain and in the USA. William Phelps Eno adapted many of the principles for the earliest set of American traffic engineering guidelines, which were later codified by Arthur Tuttle and Edward Holmes in
1932. Although some traffic devices had appeared in Britain before the turn of the century (such as a notoriously dangerous signalised pedestrian crossing outside the Houses of Parliament that exploded and killed a horse in 1888!), it was Holroyd Smith who is generally credited with the introduction of Henard’s ideas to this country in the 1920’s.
2
The planning of a new settlement in Radburn, New Jersey, provided the opportunity to add a new category to the language of urban planning, and introduced the concept of comprehensive segregation between traffic systems and pedestrian networks. Radburn principles greatly influenced new town developments in the UK, and the separation of vehicles from people remains a persuasive model for town planners to this day. Houten, a recent new town for 35,000 inhabitants, just south of Utrecht in the Netherlands adapts the segregated model with great success.
Sir Colin Buchanan’s 1963 report, “Traffic in Towns” presented the UK Government with a timely and prescient warning. Buchanan stressed that projected increases in traffic growth presented a serious threat to the quality and efficiency of towns and cities. He concluded that vehicular traffic and pedestrian activity were fundamentally incompatible, and guided planners and traffic engineers to segregate roads designed for the movement of vehicles from spaces where pedestrian activities, children’s play and public events could take place. The pedestrian precinct was born, where the architecture and urban form of the city could be isolated from traffic movements.
Figures 3a & 3b: From "Traffic in Towns" 1963. Segregating vehicles from pedestrians.
No equivalent to “Traffic in Towns” has been published since 1963. Although professional institutions such as the Institute of Highway Technicians (IHT)and the Institute of Highway
Incorporated Engineers (IHIE) have updated the recommendations and guidelines, the separation between urban design and traffic engineering has remained a constant theme in both the UK and the USA. Whilst it is rarely possible to achieve the complete separation of Radburn
2 See Lay, M.G. Ways of the world . Rutgers University (1992)

or Houten, modern traffic engineering still seeks to minimise the potential “conflict” between cars and people. Safety advertising campaigns have urged parents to discourage children from playing on roads. Pedestrian barriers and defined crossing points, underpasses and bridges have become the accepted vocabulary of the urban environment.
Figure 4: Government safety poster, 1978
Segregation versus Integration
Professor Jan Gehl from Denmark has identified four distinct models for defining the relationship between people and cars in cities 3 . In the first (Los Angeles?), people and cars simply share the same space. Without further intervention, cars will always become the dominant presence in such space. At the other end of the spectrum are cities, towns or neighbourhoods where traffic is entirely excluded (Venice?). Between these two extremes lie two parallel, contrasting approaches to the relationship. From Radburn to Houten, attempts have been made to follow Buchanan’s dictum and maintain a separation between traffic and pedestrians; to offer distinct segregated layers of infrastructure between the two. Traffic engineering and urban planning in the UK has generally adopted this model.
Figure 5: People and Traffic - Four types
The third model, and the one that I wish to explore further, grew from the introduction of
“woonerf” principles in The Netherlands during the late 1960’s and early 1970’s. Here pioneers such as Niek de Boer and Joost Váhl began to experiment with techniques to enable pedestrian movements, children’s play and social activities to be combined with traffic movements, such that each influenced the other.
4 The idea was applied to quieter residential streets, but used urban design, landscaping and local control to break down the notional barrier between “the carriageway” and the public realm. Hugely popular across The Netherlands, Joost Váhl’s ideas spread to many other mainland European countries, particularly Denmark, Sweden and parts of
3
Gehl, Jan Life Between Buildings. New York (1979)
4 Tijs van den Boomen. “Beyond the Home Zone”. NCR Handelsblad July 21 2001.

Germany. In 1999, the UK Government began to encourage cautious experimentation with such ideas through a pilot “Home Zones” programme, and there are currently some 60 such schemes for discrete residential areas complete or in development.
Figure 6: Woonerf in The Hague
But home zones turn out to be but a small manifestation of a greater sea change away from the principle of traffic segregation towards integration. Home zones gave tacit recognition to the notion that contextual design could be employed to influence traffic speeds and driver behaviour.
But pioneering safety specialists, traffic planners and urban designers in Denmark, Sweden and
Holland have started to apply principles of behavioural psychology to street design and to use the principles of legibility and context with surprising and counter-intuitive results. One of the most respected practitioners in this movement is Hans Monderman, working in the province of
Friesland in northern Holland. His work takes the principles of integration far beyond the confines of quiet residential streets, and demonstrates how urban design and traffic engineering might work together in a new paradigm.
The traffic Zone and the Public Realm
Conventional traffic engineering in the UK has defined a hierarchy of road types, suitable for various functions, speeds and traffic volumes, ranging from motorways and trunk roads, to distributor roads, estate roads and so on. Hans Monderman premises his work on a much simpler definition. On the one hand, we need space given over solely for the purpose of the movement of traffic – the “traffic zone”. Our urban settlements and economic patterns demand such infrastructure. But there are also significant elements of the road network where the movement of vehicles is only one of a range of activities – the public realm. The contrasts between the characteristics of these two worlds are striking; the traffic zone (such as the motorway) serves a single purpose. It is highly regulated by the state through rules, regulations, examination and legal enforcement. It is subject to systems analysis and is (in theory) predictable.
It is impersonal and uniform. By contrast the qualities that we most associate with a rich and varied public realm are exactly the opposite. Cities accommodate a multitude of simultaneous functions. They are highly diverse, personal, and are governed by a complex web of ever-evolving social and cultural conventions. Cities are unpredictable, and rich urban environments offer surprise, serendipity and ambiguity.

Figure 7: The Traffic Zone and the Public Realm
Clarifying whether each part of the highway network lies in the traffic zone or the public realm underpins Hans Monderman’s work. The traffic zone is not a place for anything but the movement of cars, and segregation is essential. But traffic can also coexist with other social activities within the public realm, so long as the cultural messages that govern human behaviour is made explicit. The traveller becomes a citizen. Eye contact and human interaction replaces signs and rules. But for this to work, the transition between the two worlds is made absolutely explicit.
Historically, city walls marked the transition between the highway and the public realm, and the entry through a gateway reminded the traveller of the boundary. Modern settlements have spread beyond such clear edges, and the transition has become blurred or invisible. The work of Hans
Monderman and colleagues places great emphasis on the reintroduction of very definite entry gateways. Public art plays an important role in this new approach to traffic engineering. The entry point into the town of Opeinde in Friesland is celebrated by a large tubular steel arch (echoing the common swing-bridge profile of the region). Once inside the arch, everything changes. The road surface is different. Road markings and kerbs disappear. Lighting lowers to an intimate pedestrian level. Alignments, surface patterns and drainage details reflect and underscore the principle buildings and morphology. Driver behaviour appears to respond to the metamorphosis from the traffic world to the public realm; signs and speed limits seem redundant.
Figure 8: The city gate as transition Figure 9: New urban gateway- Friesland
Central to the approach of Bjarne Winterberg in Denmark and Hans Monderman in Holland is the understanding that environmental context can strongly determine behaviour, more powerfully than legislation and formal rules. Our behaviour in a theatre or a council chamber differs from the pub or in the football stadium. We understand the signs and signals through years of cultural immersion. And we know from campaigns to change codes of behaviour, such as those for smoking or drink-driving, that such cultural mores are much more effective than legal strictures. Monderman puts it more succinctly: “Never treat drivers as idiots! We know from teaching that treating children as idiots prompts idiotic behaviour. And idiotic behaviour from drivers kills people!” Thus a rural road covered in cowpats, winding past a smelly farmyard, does not need a sign warning you of cattle in the road. Equally signs in city centres reading “Caution:

Beware of Pedestrians” or not only redundant and demeaning to the intelligence. His work suggests they also result in accidents by absolving the driver from having to use intelligence and engage with his surroundings.
Speed and Eye Contact
The use of social and physical context as a means to adapt traffic behaviour is critically dependent on speed. It is not surprising that European countries adopting principles of integration of traffic in towns are also placing great emphasis on the introduction of 30 kph
(approximately 19 mph) as the maximum design speed for all built up areas. Few towns in the
UK, with the notable exception of Hull, have made much progress with the introduction of 20 mph zones, although recent legislation was designed to encourage their use. Given the importance of speed to the idea of legible traffic design, it is worth a brief detour to explore why it appears to be so critical to the approach.
Researchers 5 such as Ashton and Mackay (1979) have long noted a “kink” in the graph relating the impact speed of vehicles with the severity of pedestrian injury. One would expect the likelihood of death or serious injury to increase with speed, but the statistics suggest a very sharp upward movement in the graph at around 20 mph. From 5% fatalities at 20 mph, fatalities increase to 45% at 30 mph, and 85% at 40 mph. A similar kink in the graph at around 20 mph occurs when comfort levels of pedestrians and cyclists are plotted against speed 6 . There appears to be a significant qualitative difference occurring at around 18-22 mph.
Evolutionary biology may help to explain this kink. Our human physiology, the strength of our skulls and physical frames, are designed to withstand impact at our maximum theoretical running speed, that of a fit young adult running downhill, perhaps in pursuit of prey. Fall and hit a rock at this speed and you will have a headache, but you will probably survive. Protection from impact above such speeds was evolutionary unnecessary.
In common with our physical frame, our abilities to retain eye contact with our fellow humans (a remarkable human ability and one that may have been essential to hunting and to social cohesion) appears to diminish rapidly when we move faster than our maximum running speed.
Research into driver behaviour suggests that eye contact between drivers, and between drivers and pedestrians, decreases rapidly beyond the 20 mph threshold. Since the effective communication of social rules and subtle messages through eye contact about status, hierarchy and priorities are essential to the functioning of public space; it appears that speed may be a factor in urban quality in a wider context than simple safety and accident reduction.
Most debate about traffic speed in towns in the UK centres on the “3 E’s” of enforcement, engineering and education.
But speed is also central to the expression of our values about urban life and the public realm. How we choose to balance the freedom of the individual to travel fast, and the wellbeing of other groups such as children and the elderly, says a great deal about our values and the sort of towns and cities that we desire. A number of European initiatives to reduce speeds suggest that speed reduction can only be effective in the long term if such values are fully debated and a consensus view made explicit. Thus in Lund in
Sweden (a city sharing similar size and characteristics to
Bath), a new speed regime was introduced without largescale enforcement or engineering. Billboards, not statutory traffic signs, announce the introduction of 30 kph (20 mph) throughout the city centre. Compliance, following 18
5
Aston University Conference – “
Managing Vehicle Speeds for Safety”
, 20 September 2000
6 Sustrans/Slower Speeds Initiative (1998)

months of public debate and argument, has proved more effective than statutory measures and speed cameras.
Figure 10: Lund, Sweden. Citywide 19 mph consensus
The new approach to integrating traffic into the public realm relies essentially on the use of eye context, and the engagement of drivers with their surroundings and with fellow citizens. Lower traffic speeds appear to be essential to allow this to happen. Removing the “safety measures” that divorce the driver from the need to engage with people, and with the place, appears to be an effective means to communicate the need for a change in behaviour, and underpins much of the counter-intuitive approach to traffic engineering now emerging from our European partners.
Achieving safety through ambiguity
Joost Vàhl, the pioneer of woonerf ideas in France and Holland, highlights the counter-intuitive nature of the new approach to traffic engineering with his conclusion that “the only way to make a traffic junction safe, is to make it dangerous!” But such contradictions appear to be borne out by the reductions in injuries resulting from some remarkable changes to busy traffic intersections in both Denmark and Holland, where ambiguity and the need for reassurance through eye contact have replaced conventional traffic controls. A number of such examples might help suggest ways in which both safety and the quality of the public realm might be dramatically improved in the UK by throwing out the conventional engineering guidelines.
In the town of Christiansfeld in Denmark, Bjarne Winterberg and the engineering firm Rambøll tackled the high casualty rate on the town’s central traffic intersection through the introduction of ambiguity and urban legibility. Rather than adding additional warning signs, road markings or traffic signals to a junction that was seeing an average of three killed or serious injuries (KSI) a year, the scheme removed every trace of conventional traffic engineers. Traffic signals were removed, along with all road markings. Instead, the notion of a “place” at the intersection has been emphasized through the surface treatment, the lighting columns, and the squared-up corners of the junction. It feels like the centre of the town again. No special priority is afforded to direction of travel, and pedestrians, cars, buses, bikes and trucks are thrown back on negotiating movement through eye contact. To many people’s surprise, not only has the KSI rate fallen to zero for three years, but tailbacks of traffic during peak periods have also reduced. It seems that the ambiguous junction provides improved capacity for traffic and fewer delays than traffic signal control systems.
Figure 11: Christiansfeld, Denmark
Similar junction treatments can be found across Denmark. In Holland, Hans Monderman has taken the principle further, redesigning many busy traffic intersections into public squares.
Changes in level, shifts in the road alignment, and architectural elements are inserted not for conventional traffic calming purposes, but merely to emphasize the peculiarities of “place”.
Observing the workings of the “de Brink” junction in the centre of the Friesland market town of
Oosterwolde, I was intrigued to hear a traffic engineer remark, with satisfaction, how many
“traffic violations” were taking place each moment in the raised, paved stage-like square that constitutes the new intersection. Trucks, bikes, cars and pedestrian intermingle with apparent

chaos and disorder, using eye contact and careful observation to negotiate the space. The guiding control of the state is absent; it relies entirely on informal convention and legibility.
7
Figure 12: de Brink, Oosterwolde. New intersection
Monderman’s approach to traffic engineering and safety demands an intimate understanding of local history, landscape, architecture, movement patterns and urban form. His designs appear deceptively simple, providing an apparently seamless integration between landscape, buildings and the carriageway. In Makkinga, a village close to Oosterwolde, the complete absence of signs and markings gives the driver an intense awareness of the ancient desire lines between the church, the pub and the village green. You know where to expect children to run out of the playground, or drunks to stagger out of the bar, and you change your driving habits accordingly.
In a suburban street, a footpath meets a main estate road at right angles. In the UK, this insignificant intersection would probably be marked by a “safety barrier” to cut the footpath from the road. By contrast, Monderman expresses the presence of the footpath into the road through special surface treatment and a slight rise in level; not enough to constitute a speed hump, but enough to draw subtle attention to the driver of the status and significance of the footpath, and the possible arrival of teenage skateboarders. It contributes to a rich, legible and humane urban language.
Figure 13: Footpath junction detail, Friesland
Figure 14: Footpath detail, Holsworthy, Devon
Possibilities for Bristol, Bath and elsewhere
Both Bristol and Bath are examples of cities that have made significant strides in recent years to adjust and improve the impact of traffic on the quality of the urban environment. Bath’s recent traffic measures have reduced the volume of traffic in the city centre, and the closure of the A4 through College Green in Bristol and the regeneration of Queen Square have demonstrated a political commitment and determination to regain high quality public spaces from the traffic domain. Popular and political enthusiasm for safe routes to schools, home zones and similar measures suggest there is scope to experiment further with some of the new approaches to
7 See NCR Handelsblad, pp.7-8 July 21 st 2001. Tijs van den Boomen. Het Nieuwe Woonerf - Weg met de regels!

adapting traffic behaviour through integration with urban design and legibility. Bristol’s “Legible
City” initiative, its recent listing as a “City of Cultural Excellence”, and its prospectus to promote its urban qualities as one of the UK’s “Core Cities” all underscore the logic of adapting new techniques for integrated traffic design.
It is not difficult to imagine the impact such an approach might have on some familiar spaces. The visitor arriving in the World Heritage City of bath is greeted on arrival, emerging from the railway station, with an elegant space framing the axis towards the Abbey and Bath Spa Hotel. But the space is filled with a muddle of bollards, kerbs, road markings and traffic signals, through which the visitor must dodge before entering the city. It is neither safe, efficient nor legible. Sweep away the clutter, accentuate the sense of arrival and quality of the space through an elegant piece of sculpture on
Figure 15: Bath, from the railway station the middle of the square, and the great city would have an entry point worthy of its status! Taxis, cars, buses, bicycles and pedestrians could each negotiate the space with no great difficulty, and the adjoining hotel and café might acquire some useful public space into which to spread their presence.
The recently redesigned Centre opposite the Hippodrome and Watershed is Bristol’s prime candidate for the use of integrated traffic principles. The struggle between the competing philosophies of urban design and traffic engineering are jarringly evident, and the re-emergence of pedestrian barriers, forests of traffic signals and signs have failed to improve the poor casualty record of this important space. “Caution: beware of pedestrians” say the signs, as if this might somehow modify the behaviour of bus and taxi drivers. “Do not cross on red man,” notices litter the lampposts, forlornly hoping pedestrians might be guided by such mysterious phrases rather than by their own observations and instincts. Such messages are universally ignored, for this is the public realm and not the traffic zone.
Figure 16: Bristol Centre. "Do not cross on the red man"

It is also worth considering how an approach based on legibility might adapt and improve another familiar piece of Bristol’s street pattern. Christmas Steps consists of a well-worn series of
Figure 17: Christmas Steps, Bristol Figure 18: Christmas Steps/ Lower Park Row spaces linked by passageways and steps running down from St. Michaels’s Hill into the Centre.
Large numbers of pedestrians follow the route in and out of the centre each day, and it remains one of Bristol’s most photographed and picturesque routes. Yet the road system entirely ignores this historic axis. Yellow lines and unbroken kerbs dissect the route on Upper Park Row. A zebra crossing on Colston Street has been placed at a distance from the axis connecting the two main sets of steps of Christmas Steps. Pedestrians ignore the logic of the traffic engineer, and continue to follow the historic axis. Here is a perfect opportunity to influence driving behaviour (and perhaps reduce pedestrian casualties) by allowing the presence of this unique urban feature to be legible in the road design.
Another example for Bristol might be Christchurch Green, close to the Suspension Bridge in
Clifton. The spire of this great church provides a magnificent focal point for this busy public space, and a number of the footpaths radiate out from the church doors. But the busy roads around the Green pay no attention the landmark, nor to the desire lines created by its presence.
Minor changes in surface and kerb details could restore legibility and coherence to the space. And once again the poor pedestrian casualty record might also improve.
The opportunities are endless, but I might take one final example from location outside a primary school on the southern suburbs of Hartcliffe in Bristol. I visited the location on Hareclive Road following a fatal accident involving a four-year old last autumn. In common with most schools, the road is separated from the school gate and its surroundings by heavy pedestrian barriers, making the school all but invisible to passing drivers. A standard “school ahead” warning sign is supposed to warn drivers, but the central white line remains continues relentlessly past the school gates. The car involved was travelling at around 41 mph. The road is clearly designed for traffic speeds of 50 mph, despite the 30 mph statutory limit. It would be impossible to differentiate the road outside the school from anywhere else.

Figure 19: Hareclive Road, Hartcliffe
By contrast, a typical primary school in Utrecht allows the surface material of its hallway and playground to continue unbroken across its nearby road, where the children are deliberately encouraged to cross the road to use the playground located on the opposite side. No barriers, signs or traffic signals constrain drivers or children. And yet the visible presence of the school spilling out across the road and claiming space on either side has a marked effect on all drivers in the vicinity. Car drivers slow to walking speed, and drive with a degree of care that no sign or speed limit could induce. Legibility is all.
Conclusion. Combining Traffic Engineering and Urban Design
The emerging techniques that aim to integrate vehicles into the public realm present a vastly expanded palette of design solutions to engineers and designers. Surface materials, lighting, kerb lines, street furniture and gateways can be deployed in ways never detailed in standard engineering guidelines. Indeed, most of the techniques would be proscribed by conventional guidelines, and rejected by a “safety audit”. However, the UK’s road casualty figures, although amongst the best for drivers in the “traffic zone”, are the second worst in Europe for pedestrians.
8 They are particularly poor for child pedestrians 9 . Denmark, Sweden and The
Netherlands have achieved significant reductions in pedestrian casualties in recent years, and the data emerging from some of the schemes referred to above suggest that safety might be significantly improved by (counter-intuitively) removing many of the measures employed since the middle of the last century.
Bristol and Bath offer ideal seedbeds for the introduction of a new paradigm for reconciling people, places and traffic. The motor vehicle continues to prove an essential component in urban transport, and is likely to remain so for many years. But challenging the traditional separation of the carriageway from the rest of the urban fabric suggests a path to build on the success of
Queen Square in Bristol and Millsom Street in Bath. A new paradigm for “Traffic in Towns” suggests a way to move towards a continuous, coherent, unsegregated public realm, where cars no longer divide neighbourhood from neighbourhood. Accentuating a sense of place appears to offer the prospect of modifying speeds and driver behaviour in ways never imagined by Henard or Buchanan. Our mainland European neighbours have shown that it is possible to combine movement and places without the need for road markings, signs and barriers. It seems to be a good moment to bring traffic engineering and urban design together to accentuate the particular qualities of place, and thereby create safe, legible cities.
8
House of Commons Transport, Local Government and the Regions Committee Road Traffic Speed Inquiry (2002)
9 Institute for Public Policy Research (ippr) Streets Ahead (2002)

Sources and further reading
Appleyard, D., 1978, Liveable Streets, University of California Press, San Francisco
Biddulph, M., 2001, Home Zones: A planning and design handbook. The Policy Press.
Buchanan, C., (Ministry of Transport) 1963, Traffic in Towns, HMSO London
Carr, S., 1992 Public Space, Cambridge University Press
CROW, 1998, Van woonerf tot erf, Ede, Netherlands: CROW
DETR, 1998 Places, Streets & Movement; A companion guide to Design Bulletin 32
DETR, 2000d, New directions in Speed Management: A review of policy.
Engwicht, D., 1999, Street Reclaiming: Creating livable streets and vibrant communities Philadelphia, PA:
New Society Publishers
Gehl, J., 1987, Life between Buildings: Using Public Space, Van Nostrand Reinhold, New York
Hamilton-Baillie, B., 2001 Home Zones: Reconciling People, Places & Transport Harvard GSD
(http://www.gsd.harvard.edu/professional/loeb_fellowship/sponsored_sites/home_zones/inde x.html)
Hass-Klau, C., 1990, The Pedestrian and City Traffic, Belhaven Press
Institute of Highway Incorporated Engineers, 2002, Home Zone Design Guidelines
Institute of Civil Engineers, 2000, Designing Streets for People: An Enquiry into the Design, Management and Improvement of Streets
Institute for Public Policy Research (ippr), 2002, Streets Ahead, London
Jacobs, A., 1993, Great Streets MIT Press, Cambridge, MA
Jacobs, A., et al., 2002, The Boulevard Book, MIT Press, Cambridge, MA
Transport 2000 (Sloman, L., and Wndban-Smith, J.), 1999 Living Streets, London
Vàhl, H.G. and Giskes, J., 1990 Traffic Calming through Integrated Urban Planning, Armacande, Lyon