Fusing Ancient Concepts into Contemporary Walkabilty By: Fanis Grammenos, Barry Craig, Carla Guerrera and Douglas Pollard Canada Mortgage and Housing Corporation, research Division Ottawa, ON, Canada Introduction: As more and more is learned about the issues surrounding contemporary movement patterns including their excessive generation of traffic and resource consumption the various health issues associated with it, the cost of traffic fatalities and the degradation of air quality etc. there has been an ever increasing demand by both residents and experts alike for a contemporary pattern which facilitate a better balance between walkability and wheeled vehicle movement and which also reduces the need to drive in the first place. This paper posits one such response to this demand: The Fused Grid, a street pattern and neighbourhood circulation approach which fuses the positive elements of many historical patterns into a cost effective, environmentally friendly, safe and walkable community framework. Not only does the grid respond to the issues of mobility but in doing so in this manner it also sets the stage for the development of a fully sustainable community Ancient Background: The Hippodamian street grid (as at Miletus below) was introduced during the 5th century, most likely to facilitate the movement of carts and chariots in a pedestrian society. This could possibly be viewed as the first time circulation system planning began to tip in favour of the vehicle. (Fig 1, ) Fig 1 Hippodamian Fig 2 Organic Fig 3 Vitruvius Prior to that patterns had, to a large extent, developed rather organically in response to natural desire lines and conditions and in certain cases to deliberately confuse invaders. (Fig 2,). Aristotle even criticized the grid as being too easy to invade. While he saw the enemy as men with swords we might see it today as men with SUVs. The other significant circulation plan that developed during antiquity was the Vitruvian radial plan which employed strong diagonals to respond natural desire lines that became the shortest and clearest route to a central point. (Fig 3) These two approaches have formed the underpinnings of almost all approaches ever since. Recent background Modern planners have had an even more acute problem to contend with: the motorized vehicle which is much stranger and goes much faster and further than the chariot while the vulnerability, speed and range of a pedestrian has remained basically unchanged There have been a number of responses to that problem including: Howards Garden City (1902) which drew heavily from Vitruvius, separating pedestrians from carts but employing pre vehicle ownership walking distances t Howard Unwin Stein Perry Milton Keynes (sector) Unwin and Stein’s plan for Radburn neighbouhoods (1928) which also separated cars and pedestrians, relying heavily on cul de sacs and footpaths to keep the two apart but which was never “scaled up” to the size of the garden city which had a population of 30,000. Clarence Perry’s neighbouhood (1929) which developed a car controlled environment using T intersections and elements of the Vitruvian approach. Corbusiers Ville Radieuse, a whole city network utilizing aspects of the Hipodamium grid to create pedestrian dominated precincts which were then served with Radburn- like green spines and footpaths Corbusier Doxiades Milton Keynes Doxiades who relied heavily on dead end streets to create a man- machine separation in a 2Km square. The Milton Keyes town plan (1967-1980)with its regional structure of arterial grid roads 1K apart, a separated pedestrian system and T intersections on local and collector roads, all executed in a topographically responsive orthoganal grid. And of course there are any number of suburban patterns employing a system of curved high speed roads and sanctuary cul de sacs. Recently, however, planners have returned to a modification of the Hippodamian grid in an attempt to insert the clarity, directionality connectivity and human scale often missing in many of these patterns. Most solutions employ T intersections, narrow or one way streets etc. to discourage through traffic in neighbourhoods and place the high velocity/ volume traffic on peripheral arterials. A deeper look at the grid in parallel with a review of the positive and negative lessons gained from other solutions suggests, however, that the grid in its pure form might not be the ideal solution and that a fusion of the best ideas from various sources might better serve both car and resident in contemporary communities. To begin, there are two elements which consistently reoccur in almost all pattern proposals: the T junction for traffic abatement and a hierarchy of streets which ensures that less traffic will reach local or lower order roads. Most models also use a separate foot path system distinct from vehicle routes. The orthogonal geometry of the grid which injects the clarity and legibility commonly sought by most patterns can be transformed to employ T junctions, looped roads and cul de sacs connected by footpaths like this Transformation of the Hippodamian grid: cross intersections are replaced with T- intersections and some street segments with pedestrian paths. or like this There are numerous transformations possible, some which avoid the cul de sac altogether in favour of loop roads which are preferred for policing, servicing and pizza delivery. An inclusion of diagonal foot paths through the green spaces subtly reintroduces the Vitruvian diagonal “desire line” for pedestrians. Five neighbourhood patterns which embody aspects of the above transformations The Fused Grid Pattern 4 neighbourhoods/unit road hierarchy Four neighbourhoods of 16 ha form a composite neighbourhood unit of 64 ha. This in turn is bound by parallel and paired one way(?) arterial roads which frame common uses. The transportation network structure continues to the next level of hierarchy. All urban space is contiguous until broken by arterials. These neighbourhood patterns embody the more important positive lessons from the 20th century model that were reviewed above: Stein’s composite block (a pedestrian precinct free from through traffic) is evident in these layouts as the green spine through which pedestrians travel to daily destinations including transit. Perry’s neighbourhood unit is replicated by combining four 40 acre fused grid blocks into his recommended 160 acre size Le Corbusiers rational transportation plan is found at a graduated scale of traffic volume within a contiguous urban fabric. All roads join rather than separate neighbourhoods. The Milton Keynes 1Km grid is present in the 4 quadrant module but the local streets are more regular and repeatable. Dioxiadis’ principles are present in the proposed layout but at a smaller (more walkable) scale (The fused grid district covers one quarter of one of his sectors). Road hierarchy is maintained but arterials are populated and fully functioning high streets as opposed to pure traffic conveyors The scale of the Fused Grid pattern is based on the current post vehicle ownership walking distance rule of thumb (5 minutes or 400meters).Within that time frame and distance an individual in any block can reach local shopping or transit without exposure to high velocity traffic and in some cases by crossing only one or two local streets. Were a car to leave the same point of origin and seek the same destination using the road system it would take about the same length of time (provided the driver could find their car keys right away). CMHC research (IBI 2007) has determined that in addition to the capital and operating savings generated by reducing road requirements by up to 10% and the increased green space and permeability resulting from those savnigs the fused grid generates o The lowest vehicle delay o The highest level of service at signalized intersections o The lowest vehicle kilometers traveled on local roads o The lowest fuel-energy use o The highest compatibility with the Ontario Child and Youth friendly land-Use and transport Planning Guidelines Further independent analysis of its walkabilty aspects has determined that because of the superior pedestrian route directness over that for vehicles along with the delight and safety of those routes and the provision of useful and reachable commercial destinations the Fused Grid approach raises the odds of walking for home based travel by 5.6% and thus reduces potential vehicle travel and the overall number of (SUV) trips. Conclusions This is a very brief overview of a substantive and ongoing CMHC research endeavour. The Fused Grid approach has been or is about to be incorporated in a number of communities cross Canada and has attracted considerable attention internationally. While the concept will have to be fully executed and lived in over a number of years before it can be considered a proven, tested approach, the research and modeling to date promises it to be an excellent response to the demands for improved walkabilty and livability . This improvement in one issue area with its inherent implications of compactness, diversity (purpose and destination), health, liv(i)ability and delight then forms the foundation for the development of fully sustainable community plan. The opportunity for a mixture of uses afforded by the arterials in close but amicable proximity to the residential neighbourhoods could evolve into shared energy and resource systems, the green spines can assume roles as surface (less expensive and environmentally superior) stormwater management systems, habitat, urban agriculture and so forth, the openness of the green squares could facilitate subtle, acceptable intensification immediately adjacent which in turn would increase the viability of the transportation and community servicing infrastructure, the interrupted grid opportunes alternative housing groupings and clusters layouts which could take better advantage of shared systems and solar access etc. etc. In short the fusion of many lessons from the past in this manner provides a solid and sustainable platform for the future. .