The days of steel or concrete bridges might be numbered. The University of Missouri-Rolla has been experimenting with new materials that are lighter and at least as strong as steel. Composite Products in St. Louis has built the first bridge at the university campus. The city of St. James is the first city to buy some of the bridges for regular traffic. The company’s president, John Unser, says the new bridges are more costly than steel, but the costs will be offset by faster construction time and lower maintenance costs.