 They had a high power-to-weight ratio to enable rapid acceleration; the prototype set record speeds on the Great Western Main Line and the Midland Main Line, and the production versions vastly reduced journey times on the WCML.The APT was, however, beset with technical problems; financial constraints and negative media coverage eventually caused the project to be cancelled.During the same period, British Rail also invested in a separate, parallel project to design a train based on conventional technology as a stopgap.