[PRCo] Re: SHJ___Interlock

[James B. Holland]

James B. Holland wrote:

>Harold Geissenheimer wrote:
>
>  
>
>>Greetings
>>There was an uphill derail on Fineview to restrain a car drifting back
>>down the hill.
>>
>>Did the S Hills Jct. derails also serve to prevent cars entering the
>>tunnel from one track sideswiping a car entering on another track?
>>
>>    
>>
>
>             This is a side benefit of the interlocking of the two as 
>mentioned by Boris.     This was all interlocked with the outbound 
>turnout so 44-, 47-, and 48-line cars would not collide with inbound 
>cars.     The interlocking was installed because the previous tower man 
>tired of constantly throwing turnouts and kept turnouts for one line 
>open too long thus causing delays on the other lines!     Traffic 
>through here was extremely heavy.
>
>             Were the derails installed Primarily:
>
>                         1.>--  To catch cars with bad brakes???????
>
>                         2.>--  To stop a car without a motorman???????
>
>             Don't know that we can specifically name The Primary Reason 
>for installing the derails without one PRCo document so stating  --  but 
>the derail served both purposes above.
>

             Bob added an addendum to the  *Automatic__Interlocking*  
article on his website and I printed it out but it is extremely 
difficult to read due to low-resolution scan, but here is a quote:::::::

                '''.....Track circuit signals 1, 2, 3, and 5 were 
interlocked with switch 1, and derail switches 3 and 5 were installed to 
protect the movement of cars through the intersection.     Short 
preliminary track circuits are used on the approach to each signal and 
presence is established on the basis of proximity of cars to their 
respective signals.'''
                 '''With the direction of traffic established for any 
route, conflicting movements are locked out and non-conflicting 
movements are permitted simultaneously.     Following movements are 
restricted until the derails are restored and the direction of traffic 
on any route is maintained as long as the preliminary to that route is 
occupied simultaneously.     A car subsequently occupying the 
preliminary of a conflicting route will obtain preference _____________ 
and desirable, since a large number of cars may accumulate on the 
approach to any signal and it is a distinct advantage to maintain the 
direction of traffic over this route and quickly to dispose of 
accumulation in the order of its importance.'''


             This statement makes it  *seem*  like runaways Were Not 
Considered  --  the derails and interlocking determined who had the 
right of way to pass thru the intersection.     Same could be done with 
simple track circuits but the derails probably simplified the circuitry 
with complex trackwork  AND  the presence of derails prevented a car 
from overshooting a stop and inadvertently stopping on top of a circuit 
to gain entrance into the intersection thus tying up the intersection 
until the car cleared.

>             Remember that  ALL  crew changes for  ALL  lines here 
>happened right here, both inbound and outbound.     And while company 
>rules Most Probably stated that one operator could not leave a car 
>before his relief was on board, It Did In Fact Happen All The Time.     
>Then there are those times when the operator leaves the car to go to the 
>restroom or to get more transfers or change  --  distinctly remember 
>operators  *slugging*  the car which is placing the reverser all the way 
>forward to pull in full dynamics if the car starts moving.     So a 
>derail would prevent a car from running away without an operator on board.
>
>
>Jim Holland
>  
>