A lot of interesting stuff on regulations.gov. Every time amtrak proposes to convert a segment to 562, a BSAP request will be posted on that site, with diagrams of its signal layout, like the following one for the section on the Harrisburg line between the current 261/562 boundary and Paoli:
https://www.regulations.gov/contentStre ... ntType=pdf
And what they have been doing is removal of all wayside signals and conversion of existing cut points, at which cab signal may drop before a restricting or worse aspect, to block points. So there'll be much shorter block lengths (1/2 or even 1/3 of the existing system) and potential shorter headways.
From the diagram, it seems that they are using so-called "Genrakode AC" track circuits in place of existing ones in this section. I did a search and found this manual:
https://manualzz.com/doc/13506556/genra ... ck-circuit
Surprisingly this Alstom-designed microprocessor-based system works completely different from US&S ones adopted 80 years ago. The US&S system uses AC or DC current pulsed at 75/120/180 ppm two-fold: providing info to both on-board systems and to receivers at the opposite ends, as required by ABS rules. Genrakode, on the other hand, uses a third frequency (156 Hz) with only 1-3 pulses in a 1.8s cycle to transmit much more info bi-directionally on rails, making the 100Hz/250Hz ones only the overlay for cab signals. By doing this, Genrakode is claimed to completely eliminate the need of wayside communication cables.
And I have a question about this design. In 562 territory there are usually absolute block signals ("C" lights or something similar) at home signals, as the movement authority for trains with a failed cab signal. Through interlocking controllers ,encoders and WIUs, they are also wirelessly linked to the ACSES on-board system so that ACSES will enforce a positive stop at closed absolute block signals for trains with failed cabs. I ran through the manual and only found a so-called non-vital "CODE 5" (on page 53) which checks the absolute block condition, and nothing else would help.
How could the signal system rely only on non-vital inputs from the track circuit to control a vital function? And without guarantee of a clear block, would it be possible for dispatchers to reverse the traffic direction of occupied blocks, something even the 1950-era book on RR signalling (American Railway Signaling: Principles and Practices) would regard as invalid? Or I had something wrong?
https://www.regulations.gov/contentStre ... ntType=pdf
And what they have been doing is removal of all wayside signals and conversion of existing cut points, at which cab signal may drop before a restricting or worse aspect, to block points. So there'll be much shorter block lengths (1/2 or even 1/3 of the existing system) and potential shorter headways.
From the diagram, it seems that they are using so-called "Genrakode AC" track circuits in place of existing ones in this section. I did a search and found this manual:
https://manualzz.com/doc/13506556/genra ... ck-circuit
Surprisingly this Alstom-designed microprocessor-based system works completely different from US&S ones adopted 80 years ago. The US&S system uses AC or DC current pulsed at 75/120/180 ppm two-fold: providing info to both on-board systems and to receivers at the opposite ends, as required by ABS rules. Genrakode, on the other hand, uses a third frequency (156 Hz) with only 1-3 pulses in a 1.8s cycle to transmit much more info bi-directionally on rails, making the 100Hz/250Hz ones only the overlay for cab signals. By doing this, Genrakode is claimed to completely eliminate the need of wayside communication cables.
And I have a question about this design. In 562 territory there are usually absolute block signals ("C" lights or something similar) at home signals, as the movement authority for trains with a failed cab signal. Through interlocking controllers ,encoders and WIUs, they are also wirelessly linked to the ACSES on-board system so that ACSES will enforce a positive stop at closed absolute block signals for trains with failed cabs. I ran through the manual and only found a so-called non-vital "CODE 5" (on page 53) which checks the absolute block condition, and nothing else would help.
How could the signal system rely only on non-vital inputs from the track circuit to control a vital function? And without guarantee of a clear block, would it be possible for dispatchers to reverse the traffic direction of occupied blocks, something even the 1950-era book on RR signalling (American Railway Signaling: Principles and Practices) would regard as invalid? Or I had something wrong?
