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Re: 3rd rail relocation -- Why?

Posted by Outside the Box on Fri Jul 20 16:07:38 2012, in response to Re: 3rd rail relocation -- Why?, posted by tunnelrat on Fri Jul 20 14:44:13 2012.

What I am asking is if has MTA looked into the option to install under running in place of top running 3rd rail.

Under running is safer to track and train crews. During emergencies its safer to first responders and anyone else on the tracks.

Yes, it probably will cost billions, but you need to renew the 3rd rail every once in a while (20-40yrs?) too. It usually coincides with track panel or major rail replacement. As the concrete ties on the LIRR will last 40 yrs or so, we can see an opening on the LIRR starting around 2040 for en mass 3rd rail replacement.

Common electrification (and signaling) standards will allow MNRR and LIRR to swap crews and equipment on 3rd rail territory. The other option is to equip the 3rd rail territory with catenary, and rail cars with overhead power equipment and retractable shoes for incompatible electrification avoidance. It would allow through running for MNRR Hudson Line to NY Penn to/from LIRR.

Subway tracks are another story. Track panels last ~20yrs, sometimes less, sometimes more. The concrete ties on the Sea Beach Line will likely last 40 yrs. The track panels on the old curved steel elevated sections of the A, 6 and 7 trains won't make it to 20 yrs, maybe 10. The train higher frequency also leads to higher wear levels on the conducting surface, and thus greater replacement frequency. The challenge is to schedule rapid replacement concurrently with 3rd rail shoe switch. It should happen over several weekends.


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