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| Re: MTA removes or increases more speed limits (1506690) | |
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Re: MTA removes or increases more speed limits |
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Posted by Catfish 44 on Sat Mar 16 13:42:34 2019, in response to Re: MTA removes or increases more speed limits, posted by SUBWAYMAN on Sat Mar 16 13:17:35 2019. And for how long have they made their own parts? |
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| (1507162) | |
Re: MTA removes or increases more speed limits |
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Posted by Stephen Bauman on Sat Mar 16 13:51:11 2019, in response to Re: MTA removes or increases more speed limits, posted by SUBWAYMAN on Sat Mar 16 13:17:35 2019. Part of the reason why they are installing CBTC is because of State of good repair. The old signal system has parts they don't make anymore. CBTC using a newer technology uses parts that are being made.Newer parts could be used to implement the existing block system at a fraction of the cost. |
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| (1507181) | |
Re: MTA removes or increases more speed limits |
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Posted by randyo on Sat Mar 16 16:38:38 2019, in response to Re: MTA removes or increases more speed limits, posted by Stephen Bauman on Sat Mar 16 13:51:11 2019. Exactly. basically the only difference between old and new signaling is that new signaling uses solid stat fiber optics rather than movable relays and copper wire. A neighbor of mine who was a signal helper told me that the switches installed at the N/E of W4 St in 1967 were electrically NX even though they were controlled by conventional GRS type levers. |
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| (1507211) | |
Re: MTA removes or increases more speed limits |
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Posted by SUBWAYMAN on Sun Mar 17 00:35:36 2019, in response to Re: MTA removes or increases more speed limits, posted by Stephen Bauman on Sat Mar 16 13:51:11 2019. Seriously? |
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| (1507220) | |
Re: MTA removes or increases more speed limits |
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Posted by Stephen Bauman on Sun Mar 17 07:54:31 2019, in response to Re: MTA removes or increases more speed limits, posted by SUBWAYMAN on Sun Mar 17 00:35:36 2019. The railroad industry's signal technology and implementation was developed about 40 years before Shannon developed the theoretical basis for digital circuit design. The rest of the world embraced Shannon's breakthrough and moved on. The railroad industry did not.One result has been that railroad signaling implementations are expensive museum pieces. The rest of the world was able to make use of ever less expensive components and implementations. The rest of the world also diverged from the railroad industry on the subject of how to build reliable circuits. The railroad industry's basis for circuit reliability is ever more reliable (and expensive) relays which they call vital relays. The rest of the world achieved reliability through redundancy. This basis for this approach was presented in a 1956 paper by Moore and Shannon entitled "Reliable Circuits Using Less Reliable Relays." The next revolution that the railroad industry missed was the substitution of Programmable Logic Controllers (PLC's) for hard wired digital circuits after 1975. A PLC is a computer and program that simulates any logical circuit. The PLC's program accepts any logic circuit as data. PLC's are most responsible for the factory floor automation that has taken place since 1975. The PLC's have become commodities and are designed to function in harsh industrial environments. There are approximately 15K individual signal blocks. If each cost $500K to implement and install with a PLC, then the total replacement cost would be $7.5B instead of CBTC's $40B+. |
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| (1507222) | |
Re: MTA removes or increases more speed limits |
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Posted by Steamdriven on Sun Mar 17 09:31:30 2019, in response to Re: MTA removes or increases more speed limits, posted by Stephen Bauman on Sun Mar 17 07:54:31 2019. then the total replacement cost would be $7.5B instead of CBTC's $40B+. And therein lies the problem. Spending less of your money means less can be used to buy votes, buy union support, or be shoveled out to pet causes. For those poor pols below the billionaire level, it mean fewer rivers of cash the day after leaving office. |
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| (1507224) | |
Re: MTA removes or increases more speed limits |
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Posted by Stephen Bauman on Sun Mar 17 10:20:32 2019, in response to Re: MTA removes or increases more speed limits, posted by Steamdriven on Sun Mar 17 09:31:30 2019. Spending less of your money means...That is definitely the problem. However, it's not limited to your enumerated categories. It's pervasive throughout society. A project manager's salary varies directly with the project's cost. Somebody managing a $5M project will make much more than a manager who can be trusted with only worth $500K. More expensive solutions are preferred to less expensive ones during engineering analyses. |
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