Biggar Access Road (Smart Surface™)

Client: Scottish Water

Location: Biggar WWTW



The access road into Biggar WWTW was constructed as a typical unbound access road. The road was subjected daily to HGV traffic and was in use by groundskeepers of adjacent holiday park and golf course. The unbound surface required maintenance every 4-6 months with potholes forming regularly making access difficult and posing a safety hazard to patrons of the holiday park.



Mackenzie Construction posed the Smart Surface solution to this problem to provide a stable running surface that would drastically reduce the maintenance requirements while also being a sustainable solution.

The host soil for this application largely consisted of well graded crushed aggregate that had formed the access road previously. A small quantity of aggregate was imported to improve cross falls and drainage characteristics of the final surface.
Once the binder had been mixed into the soil, it was graded using the excavator and cross falls obtained. Compaction followed this.


To obtain a highly durable and high friction surface, a bitumen based two coat surface dressing was applied to the compacted surface. This left an aesthetically pleasing finish that has proven to be highly durable in the subsequent years with CBR results increasing year on year.

The duration of works was also significantly reduced. The first application was done in June 2018 and the road remained open throughout the works with tankers restricted over a three-week period. This compared to an 8-10 week road closure for traditional road resurfacing.

“When funding became available, we asked Mackenzie Construction for a quote for tarmacking the road and they offered to do a demonstration of Smart Surface. We weren’t sure how well it would hold up under the stress of fully loaded tankers so we did a test on a 10-20m stretch. It seemed solid under use and the quote for the full road was half the price of tarmacking, so we decided to go for it.”

Scottish Water