A route with wide curves

Stunning lakes and vast, dense forests are the staple of the Swedish landscape. It is no different along route 55, better known as “the Mälaren diagonal”. Between the cities of Enköping and Strängnäs, this provincial motorway passes countless woods and three lakes, all part of the lake district of Mälaren. At the junction with the Hjulstafjärden, route 55 was constructed as a movable bridge, to enable shipping traffic. This bridge needed reconstruction, to allow bigger ships to pass safer and more quickly. Together with Zwarts & Jansma architects, BoschSlabbers drafted the Visual Quality Plan for the new cross-river connection. The new Hjulsta bridge is kept relatively low, in keeping with the slightly sloping landscape. The new route flows, along wide curves, to bring more visual variety to the landscape and to turn the crossing of the Hjulstafjärden into a certified experience.

An integral approach

The existing landscape was the main starting point for the bridge design. Spatial analysis uncovered a variety of qualities and issues in the current landscape. For example, the old bridge is not accessible by foot or bike, and the long dam in the water is a limiting factor for the development of aquatic ecologies.

Know-how and experience were shared in international cooperation between a Finnish-Swedish engineering company and a Dutch design team. Sharing different insights from the start created a full picture of the situation in early stages of the process. Collectively, a number of models for the new bridge were developed. The alternative of preference was then developed for the Visual Quality Plan.

Ancient oak forest reconnected

To the north, the road runs through a valuable nature reserve, cutting it in two. The reserve consists of meadow landscape with ancient oaks, grazed for centuries by cows. The unique oak forest, called Hjulsta Ekhagar, is a habitat for the rare hermit beetle (Osmoderma eremita). This is also the ground for its Natura2000 status. To help protect the beetle, the bridge abutment was shaped in such a way that the height of the road remains low throughout its passage of the oak forest, enabling the beetles to fly unobstructed from crown to crown. Furthermore, almost all trees are preserved, and the plans make room for extra trees, to better connect the two sides of the nature reserve.

New meaning for an old abutment

Sustainability considerations prompted the decision to leave the old abutment on the northside of the Hjulstafjärden largely intact. The spot is of interest for people who want to watch the boats passing. Here, the spectacle of the new bridge closing and opening will be visible from up close. It also is the access point to the eye-catching control room that marks the spot. In addition, the lookout on the old abutment tells the story of the old bridge, dating from 1953. It has become a beautiful place to pause along the route 55, and regenerates its significance.