Steep rises in steel prices are prompting engineers to turn to using alternative materials for road bridge construction.
Steel prices have risen almost 16% since February driven by higher demand and raw material costs.
In addition to the price hikes, construction budgets are being squeezed and the industry is under increasing pressure to make projects more environmental friendly. As a result, clients such as the Highways Agency are considering new alternatives to more traditional steel and steel reinforced concrete structures.
The Agency recently used fibre reinforced polymer bridge deck over the M6. The installation was part of a research project that found that the bridge’s high strength to weight ratio allows it to be used in more “innovative and more efficient structural forms with light and longer spans”.
Further afield, more traditional timber has been resurrected as a good alternative to steel and steel reinforced concrete.
Austria and Germany have a number of timber highway bridges, which have the added value of having a much lower embedded carbon value (the amount of carbon required to produce the product) than steel or concrete.
“It’s possible to produce highway bridges of up to 100m [long] in timber,” said Ramboll director of buildings Simon Smith.
However, the majority of bridges on the Agency’s network are steel reinforced concrete and it may take some time to shift entirely to using alternatives.
If a new material is proposed it will need to comply with the Agency’s Design Manual for Roads and Bridges. Where the manual does not cover new materials the Agency will work the designer or contractor to ensure that the proposal is feasible, cost effective and buildable and that safety, durability, appearance and maintenance requirements can all be met.