The problem is there is a heavy investment in tank
cars that do not meet current standards and considerable expense to be borne in
upgrading them. Some tank cars, with tank wall thickness less than is desired, cannot be upgraded. Proposals for anti-climbers, different couplers, as well as a means for progressive failure construction have been advanced. There is also, unfortunately, a difference of opinion regarding the potential for catastrophe and the influence of powerful lobbiests.