dead rail

dead rail

[′ded ‚rāl]
(civil engineering)
One of two rails on a railroad weighing platform that permit an excessive load to leave the platform.
References in periodicals archive ?
Churchill has a long straight, Pimlico a long-standing front-running bias due to the harshly graded turns, and Belmont often has a dead rail and is much more galloping than the other two.