Getting enclosure right: creating a comfortable public room
Creating public spaces that pedestrians want to occupy and feel comfortable in.
Enclosure refers to the extent to which buildings, walls, trees and other vertical items frame a street and public space. Public spaces that are framed by vertical elements in relative proportion to the width of the space between the elements have a room-like quality that is comfortable for people. Creating these outdoor rooms is important to creating places that pedestrians want to occupy. Gordon Cullen, in his book “The Concise Townscape,” states that “…enclosure, or the outdoor room, is perhaps the most powerful, the most obvious, of all the devices to instill a sense of position, of identity with surroundings…. it embodies the idea of here-ness.”
In an urban setting, such as a traditional commercial district or mixed use neighborhood, enclosure is formed by an unbroken line of building fronts. Traditionally, this framed the thoroughfare in a ratio where the building height and the distance from building to building were equal. In locations where the ratio is not what is desired, for example, the distance between buildings is more than twice the height, pedestrians can feel exposed and uncomfortable. To correct a problem like this other vertical elements are used to frame the space. If the road surface is too wide, a median with trees can frame the space. Street trees can also be used to frame a much more enclosed space between buildings and the edge of the sidewalk. If trees are not a viable option, street furniture such as banners and building awnings can create the physical enclosure of a room.
The reason behind creating enclosure for pedestrian areas is the twin needs in humans for prospect and refuge. Prospect is based on the pleasure received from views out onto a space and refuge is based on perception of safety and observation of a defined space. There are other urban design concepts that contribute to these two factors such as complexity of design, but enclosure is the main design element behind prospect and refuge.
Contemporary zoning often overlooks enclosure ratios. Form-based codes are one tool to bring enclosure ratios into zoning and create more productive public spaces. Michigan State University Extension offers training and technical assistance to communities that are in interested in form based codes and urban coding. For more information on placemaking visit www. Miplace.org or contact a Land Use Educator for more information on these training programs.