Hoevelaken Junction

Motive

The Hoevelaken Junction (A1/A28) is a major point of congestion for both local and commuter traffic, often resulting in long traffic jams. In 2008, Rijkswaterstaat initiated a planning study, to investigate how the traffic problem at the junction and adjacent roads, could be resolved. In consultation with the municipalities in the Amersfoort region, and the provinces of Utrecht and Gelderland, the Minister of Infrastructure and Environment decided to engage the contractor market early in the planning study. The tender provided the opportunity for one private party to secure a contract for completion of the planning study and the realisation of the project.

DBFM

The project is a DBFM tender (Design, Build, Finance & Maintenance). Three parties, including the Ontknoping Consortium (Heijmans, Ballast Nedam, Witteveen + Bos), are bidding for the contract. The Department of Public Works has awarded the contract for construction of the actual project to the Bam and Van Oord Consortium.

Approach

The main design emphasises what, in our view, are the two main perspectives involved in the project: the perspective from the road; and from the surroundings. Each aspect of the design has been developed with both these perspectives in mind. In this project, we look for synergies between the different aspects of the junction: traffic, noise, nature and recreation.

Result

Inner world

To create the feeling of an ‘inner world’, the ‘bowl’ shaped landscape is deliberately left as empty as possible. The design replaces the multiple, inner loops of the existing junction with compound carriageways so that only the A1 and A28 cut through. The ‘bowl’ shape has been designed with a high edge and a lower edge, to emphasise the scenic qualities of the landscape and due to considerations concerning the altitude of the roads.

Slopes

The slopes towards the centre of the ‘bowl’ have a smooth contour and gentle incline (1:10). The slopes to the outside of the ‘bowl’ are very steep (1:2). Clumps of Robinia are loosely scattered around the rim of the ‘bowl’. These trees add additional height to the edge of the ‘bowl’ shape, which emphasises the massive scale of the junction, placed within such a vast landscape.

Ecological significance

Small, ridged terraces are created in the slopes allowing flora to develop naturally along the gradients. Due to the incline of the slopes, rain water run-off from the roads can seep downwards into the lower part of the ‘bowl’, which will be used for water storage. This part will be permanently filled with shallow water, and develop into a breeding ground for fish and amphibians. Thus, new ecological microcosms are created.

Outer world

The 'outer world' is an important part of the design, which emphasises the visual relationship between the surrounding business parks and the environment. Sufficient space in the surrounding business parks is dedicated in the design to ecological and water management (storage, purification).

The 'outer world' contrasts starkly with the emptiness of the ‘inner’ world. Therefore, the design provides for vast ‘parkland’ areas to integrate the highways entering and exiting the junction. The landscaping of the groups of trees, grass, and the smooth finish of the steep slopes, are consistent with the design principles that are applied to the other terminals and junctions along the rest of the A1 motorway. This guarantees the cohesion of the project within the larger landscape. Tree species have been selected which are consistent with the native species of the Gelderland Valley – an assortment of oak and birch.

Landscape & art

The iconic design of this junction is emphasised by the consistency between the features and lines of the natural landscape, and the architectural design itself. The flowing lines of the landscape are neatly integrated into the architectural design of the junction – the result is a collection of sculptural elements with a visual language based on curved lines. The retaining/support structures of the junction are decorated in the same curved ‘language’, with lighting masts placed alongside the roads in a unique, circular design.