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| Re: (M) via Chrystie Street Cut delayed? (937098) | |||
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Re: (M) via Chrystie Street Cut delayed? |
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Posted by Randyo on Tue May 25 15:38:27 2010, in response to Re: (M) via Chrystie Street Cut delayed?, posted by trainsarefun on Tue May 25 15:13:31 2010. Type VIII is an all concrete roadbed with the rails bolted to the ties over padded tie plates. Type II consists of short wooden ties imbedded in concrete. In both types, there is usually a trough cast into the concrete primarily to allow for drainage of water and for debris and refuse to go well below the rails. In stations the trough has an additional purpose of providing a place for a passenger to seek refuge in the event he/she falls off the platform so that the train may pass over without inflicting serious if any harm. The original type II which is found on many of the IRT and BMT dual contract lines was only installed in station areas and in addition to being cemented in, the ties were also bolted to the concrete. Newer portions of the 14 St Line and the entire IND were originally built with type II roadbed but it was found by that time, that the bolts were not needed except on sharp or high speed curves. On some especially heavy curves, every 5th tie (usually the 3rd rail tie) extended completely across the trough to maintain the track gauge. This has become known as the "modified" type II and has often been used in newer installations on the IRT and BMT where ballasted roadbed is being replaced by concrete. In some cases the modified type II has even been used to replace the original type II in some of the IRT and BMT stations and has made an occasional appearance on the IND. The latest type II installations now have short sections of rebar through the ties to provide additional stabilization after the concrete is poured. Although that would seem to eliminate the need to have the 5th ties going completely across, and allow the installations to be unmodified type II, NYCT MOW continues to install the modified type II anyhow. As to chipping out taking a long time, in 1958, the entire Bway IRT from 145 St to Dyckman which was type I (ballasted), was replaced by new ballasted type I roadbed and the removal of the old roadbed didn't seem that much faster than chipping out and with modern machines such as the Pettibone Speedswing, chipping out shouldn't be all that time consuming at all. |
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