Bristol Line track circuits (was Old photo of Rural Retreat)

[NW Mailing List]

Abram,
You always ask interesting and almost impossible questions ha ha! It took
some digging, but I did find the answers.

The Bristol Line had DC track circuits after the 1946-47 signal upgrade.
So, they were changed over during the signal upgrade.  They were steady
voltage DC circuits.  They remained in service, with modifications through
the years as sidings were removed, until 1996-97 during the pole line
elimination.

Ben Blevins

On 3/23/13, NW Mailing List <nw-mailing-list at nwhs.org> wrote:

> Just to clarify a minor point (for those who might not know which side of

> the tracks Rural Retreat depot was located on, and therefor might not

> understand an east/west reference)...

>

> The erstwhile Mr. Blevins is referring to the semaphores at far right in

the

> image. They are automatic block signals of the semaphore type. He is not

> referencing the Train Order semaphores located in front of the station

> building which, of course, were manually operated.. This might have been

> immediately obvious to some, but it wasn't to me.

>

> Now a question for Ben: The first automatic block signal system on the

> Bristol Line used AC track circuits. (This was because there was no way to

> charge the "storage batteries" necessary for a DC signal system at the

time,

> and the railroad hung 4400 volt AC on its own pole line to power the new

> automatic block signal system.) How long did the AC track circuits remain

in

> use? Were they changed to DC track circuits during the CTC program of

> 1947-1948, or were they left in place during the transition to CTC?

>

> -- abram burnett

>

>

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