Site3D Case Study
Category: Residential
Company: Persimmon Homes West Scotland
Status: Planning (2023)
A residential scheme for 220 units by Persimmon’s in-house team. Persimmon had very recently made the switch to Site3D from their previous software when they began designing this project. The team would need to find ways to blend in to the site’s rural village surroundings, to design sustainably, and comply with some unusual traffic-calming measures in line with local council standards.
Development Layout
Engineers were required to keep the existing trees and stone walls running around the edge of the site, so that the appearance remained in-fitting with the style of older villages in the area. They would need to tie-in to the levels of the site boundaries, and to two existing roads: a main road running directly along the right-hand boundary and a private road running along the left.
“Site3D is very visual. It’s very easy just to put sections in and to quickly have a look at the existing ground, and see the level differences and if you need to move or adjust a layer to suit, or work out the maximum variance, and from that point you can make decisions.”
– Arif Anees, Senior Design Engineer at Persimmon Homes West Scotland
Engineers established that they would have to off-set the private road away from the boundary in order to to achieve the maximum gradient, in this case 1:3, so that everything could fit without the need for retaining walls. They were also able to model a footway that linked this existing road to the new ones in the development.
“Before, we never really modelled footways just because there weren’t the tools to do it. In Site3D you can very quickly model them in, check the gradients, check that they work, change a road if you need to to suit the gradients that you need to achieve ... And again, it’s really easy to do.”
– Arif Anees, Senior Design Engineer at Persimmon Homes West Scotland
The roads in this model are designed in a particularly complex and unusual way. The brief required that vehicles would be kept to a 20mph speed limit throughout the development, but, in line with the local council’s approach to traffic-calming, it would need to be done by changing the road alignments instead of conventional speed bumps or raised tables. So, to ensure vehicles would be kept to 20mph, all roads in this design have frequent narrowings and widenings and zig-zagging horizontal transitions.
“In terms of modelling the roads, it’s been amazing, because these roads are pretty complicated – there’s a lot of changes in direction, narrowings, widenings, different sorts of junctions – and Site3D very easily allows you to model this kind of stuff. Before you probably wouldn’t even try this kind of detail – you’d just guess something close or do some bits manually ... Previously it wasn’t nearly as good, or even enjoyable to be honest, to do this.”
– Arif Anees, Senior Design Engineer at Persimmon Homes West Scotland
Finally, the design has kept and enhanced the green space throughout the site. As well as keeping existing trees and hedgerows and adding landscape buffers at the boundaries, the team have made space within the site for newly-planted woodland and parks. A new large pond, which, as well as being an attractive feature for residents and a home for local wildlife, will also work as a SuDS feature. This pond will function as a basin to filter and attenuate surface water, ensuring that it can rejoin local watercourses at a suitable flow-rate and free of impurities.
“Site3D has good tools to quickly put in a basin, check the volume, make sure it works, and it’s very visual in the way it shows it. And when exporting the drainage into simulation software, it takes all the data from this model. So you’re not redoing anything – it’s intelligent like that. All the information that you need is exported out so you never need to mess around.”
– Arif Anees, Senior Design Engineer at Persimmon Homes West Scotland
The Persimmon team have been able to create a design that confidently achieves complex and detailed infrastructure, while also being sustainable and in-fitting-with its rural surroundings. When built, this development will provide 220 new homes to meet the needs of the local housing market.
