Setbacks & Building Placement
This design element addresses how the factors of setbacks and building placement affect the size and placement of multimodal transportation infrastructure and create a comfortable human environment within a site development.
The minimum distance from the street right-of-way line to the lot line that establishes the area within which no structure can be erected.
A setback is used to create a buffer area which protects buildings or structures from the road by mitigating noise levels, by providing a safety zone and by improving aesthetics through landscaping or screening. Setbacks are a function of the area type, land use and the functional classification of the road.
The setback area and the right -of-way buffer area do not serve the same function. Setbacks are not intended to accommodate the future widening of the road therefore they should be measured from the ultimate right -of-way. See RIGHT-OF-WAY ULTIMATE design element. If no ultimate right-of-way exists, then setbacks should be measured from the existing right -of-way. The use of a setback measured from the ultimate right -of-way allows for the future expansion of a road while preserving the property and the building values when the road is widened.
- On roads of similar classification, there should be consistent setback in all adjacent zoning districts.
- Setback values should be determined according to the functional classification of the roadway.
- The following chart is suggested as a reference in determining setbacks. The process of determining setbacks is complex.
|Growth Area||Rural Area|
The relative location of a building or buildings and other site elements on a lot or property.
How a building looks, its placement on a site and its relationship to adjacent structures and the immediate surroundings are some of the most significant influences on the character of any community or development (Pennsylvania Standards for Residential Site Development, Pennsylvania Housing Research/Resource Center, 2007).
According to the PHRC, the following factors should be considered when placing buildings on a site:
- Building Design
- Lot Size
While these may be the primary factors for determining where buildings are placed, the relationship between the buildings and the circulation system utilized to access the building(s) is another factor that should be considered towards the creation of outdoor 'spaces' and a comfortable human scale environment. Parking lots, driveways, walkways, trails, etc. not only provide access to, but also limit where people may congregate in the outdoor environment.
For example, a design principle of many corporate parks constructed in the 1980's era placed the parking, main building entrances, and any pedestrian walkways on the opposite side of the buildings from the primary road frontage. While the design intent may have been to create the look of a green campus-like environment, the lack of pedestrian facilities on the frontage side results in a relatively sterile exterior due to a lack of apparent human activity. There is simply no way to tell if these developments are full of life or if they are completely empty since the frontage always has the same appearance. This appearance has a direct effect on the marketability of the space within those buildings.
Successful developments achieve a balance between the functionality of the vehicular circulation system and the comfort and safety of the pedestrian environment, including minimizing conflict points. The sooner one may enter a comfortable pedestrian environment connecting to a building from the time they exit their car, the better the human experience will be for that development.
Building heights are another factor affecting the pedestrian experience. According to ITE's Designing Walkable Urban Thoroughfares: A Context Sensitive Approach "Buildings are the primary feature of urban contexts that create a sense of definition and enclosure on a thoroughfare-an important urban design element that helps create the experience of being in a city and in a place that is comfortable for pedestrians. The threshold when pedestrians first perceive enclosure is a 1:4 ratio of building height to thoroughfare width-typical of low density environments. In denser urban contexts, height-to-width ratios between 1:3 and 1:2 create an appropriate enclosure on a thoroughfare."
While building heights and the inter-relationship of multiple buildings plays a significant role in creating outdoor spaces, pedestrian environments require the combination of subtle yet effective barriers such as curbing, fences, railings, bollards, planting beds and/or trees to provide the necessary separation from vehicular circulation to create a safe and comfortable space.
- Always consider the relationship between building placement and both pedestrian and vehicular site circulation and how it will impact not only safety but also the pedestrian friendly experience of the development.
- Provide for outdoor gathering spaces where appropriate, particularly in commercial and employment centers, urban centers, and suburban centers. These spaces help to create the appearance of vitality within a development.
The entire Multi-Modal Handbook PDF may be downloaded here.