A new bridge across the Missouri River at Lexington is as much as six inches too low. The bearing assemblies, which are metal plates on which the girders are placed, are too short. The girders already are in place. Some of them weigh 100 tons and are 120 feet long. The bridge was to open in August, which already was later than planned. Now it’s not likley to open until next year. The contractor says the company’s working hard to solve the problem.