Amata Bridge is located on the country’s main A2 motorway on the stage from Riga–Sigulda–Estonian border (Veclaicene) 76,30 km. Length of the existing bridge: 46.6 m, length of the arch section: 25.0 m, maximum arch height: 4.6 m (7.3 m from the riverbed). The wear and tear of the bridge had reached a critical level – numerous large cracks could be seen in the vertical supports, including above the arch, and the load-bearing armature was corroded. The driving surface was in a very poor condition and the pavement section was practically useless. The only parts of the existing bridge fit for continued use were the arch supports.

During construction works, traffic was redirected along a bypass downwards of the existing bridge. Due to the provisions stipulated by the Client, which decreed that the temporary one-lane bridge had to be able to carry a 80 t large load (two heavy goods vehicles (each weighing 40 t) one after the other at a distance of four metres), it was necessary to seek a suitable metal bridge abroad. The solution was found courtesy of the globally renowned British company “Mabey and Johnson”, which has been manufacturing module-type (prefabricated) metal bridges with almost any load bearing capacity and span since 1943.

Two engineers from SIA 8 CBR visited the plant where they not only inspected the new structures but were also introduced to the company’s main plant – an almost fully automated plant in Wales, as well as existing and former “Mabey and Johnson” bridge types in service. One should note that almost half of the piles of products were occupied by products intended for delivery to the US Army in Kuwait and Iraq.

The length of the temporary bridge was 40.5 m. It was assembled from individual panels and its full length was slid into place, using the not yet assembled structures of the bridge itself as a counter-weight. Six lightweight bridge stages served as a 27 m long cutwater. It took four days to complete the works involved in assembling the temporary bridge.

The building project for the new bridge was combined with the opportunity to straighten out the vertical plan of the relevant stage of road. The existing longitudinal profile of the road was raised by 3.5 m, increasing the length of the newly built bridge to 65 m. The length of the arch remained constant. The design of the new bridge remained largely unaltered.

More than 257 t of reinforcement bars and 1,420 m³ of concrete, including reinforced concrete elements, were used in the construction of the new bridge. The elements supporting the bridge on both banks of the river were reinforced with the help of 126 m³ of piles of large boulders in special gabion meshes and mortar paving across an area spanning 389 m². Special mention should be made on the expansion of the bridge’s arch supports and their combination with the existing arch supports. In order to achieve the consistent functioning of both old and new components under the increased loads of the bridge, 1,070 drill holes were created in existing bridge supporting elements and an equal number of anchors were glued in using HILTI technology. It should also be noted that “penguin” type barriers rarely used in Latvia were used here in the form of railings along the sides of the bridge.