The last three decades of the 20th century saw a period of large-scale bridge building in Europe and Asia. Current research focuses on using computers, instrumentation, automation, and new materials to improve bridge design, construction, and maintenance. These loads include the weight of the bridges themselves, the weight of the material used to build the bridges, and the weight and stresses of the vehicles crossing them. Combination bridges may incorporate two or more of the above designs into a bridge. Each design differs in appearance, construction methods and materials used, and overall expense.
Some designs are better for long spans.
Beam bridges typically span the shortest distances, while suspension and cable-stayed bridges span the greatest distances. Water and Sanitation Services, Water Treatment, Group 5 water treatment, WSSA water treatment, Water Services, Water Services.