WASHINGTON (AP) — Senators and shippers complained Wednesday that widespread delays in freight rail shipments are hurting a wide array of industries and driving some companies out of business, and they expressed doubt that the railroad companies are doing all they can to fix the problem.

The delays, which escalated late last year and continued through the spring and summer, appear to be the result of too few rail cars and too much demand from shippers, officials representing the agriculture, auto and chemical industries told a hearing of the Senate Commerce, Science and Transportation Committee. Lawmakers displayed a photo of a giant mound of wheat standing in the open because North Dakota farmers can’t get a railroad company to ship it.