PROSPECT: Site Visual Capacity Analysis
A New Approach
The use of terrain modelling to assist site design and area planning has been much overlooked. In many cases we are asked to do a ZTV analysis or create photomontages for a fait accompli, which has a battle through planning because of objections to the appearance.

We have developed a better way of doing things, which asks the visibility questions to give a more useful result right at the start. The advantage is that the design process is informed by the predicted visual capacity of landform to 'absorb' new development, rather than having to mitigate for problems later. The cost saving of this to developers is not only in building but in consultancy and planning too.

It's a distinct and powerful analysis to introduce at early involvement stages to develop a stronger role in the team and influence site planning driven by landscape and user needs. With this simple set of information up-front you can argue where on a site to place the tallest buildings, where they will have least visual impact and, where to concentrate low rise development in the most exposed areas. Conversely, where is the best place to site a landmark!

Method
We start by creating a digital terrain model (DTM). Existing hedgerows and woodlands or urban areas and be added, which act as secondary visual barriers. From sensitive viewpoints we can then ascertain the heights of development which cannot be seen within the site area and the map is subsequently overlain with contoured colour bands. These indicate the maximum visual capacity. Since this is at site / OS coordinates it can be used by planners, architects and landscape architects as an overlay for site design.

The Impact of Time
We can 'grow' boundary vegetation and show the effects of mitigation, mounding and tree planting, to demonstrate the reduced impact over time. Typically we might show a 5, 10 or 15 year scenario which helps develop a phased construction programme as well as inform the ultimate maximum visual capacity of the area.

More detailed analysis
The information we store in the results isn't simply a contour overlay, although this is arguably the most compelling result. It also tells us which particular viewpoints are limiting the site's visual capacity - another useful analysis to develop cost effective mitigation and phasing strategies.

Benefits
- position buildings where they make lowest impact (alternatively find the best location for a landmark)
- identify vistas and exposed areas
- assess the effectiveness of existing and proposed screening
- reduce costs of mitigation, leaving more of the budget for quality landscape design in key areas
- reduce the cost of ZTVs, photomontage and CGI visuals
- design site layout which is sensitive to local concerns
- reduce public alarm and opposition
- eliminate planning problems before they become an issue
- plan site layout and phasing sensitively
- streamline planning process

Applicable to
- housing developments
- mixed development sites
- business, distribution and retail sites
- urban planning