I never tried the "bridge" method ,despite lots of idle time and idle thoughts rolling down many a mile on the old narrow gauge .One time Paul Connor told a tale of a train of steel that was routinely transferred from the steel mill at Minnequa down grade to Pueblo yard .The train was always the same consist,some old cars making a trasnsfer of raw steel from one mill to the other . They leaked a lot of air .Engineers complained they could not handle this train smoothly down the hill . One old engineer had a technique ,though . He would roll out of Minnequa,and set the brake valve in the holding position . By bottling the train air the leakage slowly set the train brakes . It was a little quick at first ,but the train slowed in the s-curves ,rolling smoothly into East Roger Yard .I tried it with leaky trains down Cumbres ,starting out with a small set to prime the brakes.
It worked ,giving smooth rides with long sets .