Highway 4, Kirri-Tikkakoski

North of Jyväskylä, the Vt 4 Kirri—Tikkakoski road project of the Vt 4 Kirri—Tikkakoski road project built a new motorway between Kirri—Tikkakoski and Vehniä. A-Engineers, as partner of the main implementor Destia, was responsible for the bus design as well as the rock structure design of the avenues. The motorway section was opened to traffic in late 2021.

Some 5 million cubes of earth and rock masses have been moved from a 16-kilometre stretch of road, of which about 1.5 million cubes of rock cuts have been removed. The road project was completed more than half a year faster than the original schedule thanks to data modelling. For rock open cuts, data modelling utilized photogrametric modeling. 

Upon completion, the project improved safety, driving conditions, and safety of transportation on Highway 4.

Kirrinmäki's rock openings are an exceptionally demanding rock building site due to its height of more than 30 metres. The cuts, mined into two different levels, span a distance of about 800 metres. In Sakarinmäki, the rock openings are 600 metres long and 15 metres high at its highest.

Parallel road links and light traffic lanes were also built in connection with the new motorway to the four road, which were over 35 kilometres in total. The project also involved the construction of six interchanges along with several bridges. Improvement of Acting 4 Kirri—Tikkakoski

The STK contract model of the Bus Agency, where Destia is the main implementor. A-Engineers served as Destia's one design partner for the project.