Is an interlocking tower needed?

[markpierce]

I'm modeling, 1955 era (mixed diesel-steam era), an imaginary secondary mainline with a junction with two branchlines. The mainline is operated "blind," that is, no CTC but with timetable and train orders. I've built an interlocking tower, but don't know if locating this structure at such a junction would be "prototypical" of Southern Pacific Railroad practice.

Mainline traffic will typically consist of (1) a daily round-trip express/passenger train, (2) twice-weekly round-trip coach/pullman passenger trains, and (3) about six freight trains in each direction. In addition, the first branchline will usually have two round trips (mineral and general freight), while the second (to a military base) will usually have about one. Almost all of the branchline trains will originate from a division point about thirty miles south of the junction.

The junction consists of (1) a passing siding about one mile long, (2) at the south end there is a passenger/freight depot and a house/team track siding, (2) at the north end, there is a turntable and locomotive servicing track for helper locomotives for the grade north to a pass, and to service and redirect branchline trains to the branches as needed. Schematically, the junction looks like a backwards K, with the mainline running north/south, and one branchline heading northwest, and the other branchline heading souwthest. The branchlines intersect the mainline about in the middle of the siding. The siding junction's double-ended siding is "lapped," that is, there is a crossover connecting the siding in the middle, just south of where the branches meet the mainline. The depot is manned 24 hours a day and is about a quarter mile south of the junctions. If I was to have an interlocking tower, the middle of the siding where the crossover and branchline junctions are located, would seem to be a logical location.

So, specifically, (1) does the traffic justify the expense of a tower and its additional personnel, and if so, (2) what portion, if not all, of the turnouts would the tower control, and despite the district being "blind", (3) what type of signals are needed, if any, and if not (4) what facilities should otherwise be located about the junction (such as telephone boxes)?

Thanks for your advice.

[DSchmitt]

Even if the traffic doesn't justify the expence of an operating tower, it can still be there as a rellic of an earlier time.

[markpierce]

Traffic was highest in the post-WW2 years, and rarely exceeded 30 trains a day, not counting helper movements.

[dehusman]

I would put the tower there. The tower would be at the largest concentration of switches. If the tower was supposed to be there from an earler time, then it would be or would have been a manual interlocing using "levers" to operate it. That means that it would be limited to controlling switches within about a 100 -200 yard radius of the tower. You want to position the switches so they a concentrated together and near the tower. The SP commonly put a CTC island or interlocking at junctions.

Dave H.

[jimrice4449]

I worked for the SP at Burbank Jct and Saugus in the sixties. At Burbank the tower was located at about the middle of the two crossovers. At Saugus there was a junction w/ the Santa Paula branch that was very rarely used (mainly for detours) but there was a CTC board in the depot that controlled Power switches at the ends of two lapped sidings (the switch to the Santa Paula branch was manually controlled by the train crew using it). After a major wreck at Burbank Jct the Armstrong plant was replaced w/ a CTC board operating power switches (track layout remained the same) located in a ground level tin shack. Bottom line...you can pretty much do what appeals to you. Personally, I find interlocking towers pretty appealing.

[oldyardgoat]

Your description of your junction sounds very similar to one I am modeling, which is Sand Creek Junction, near Denver (CO). In this case, UP's First Subd. is connected to two similar tracks such as you describe, one is a spur to an oil refinery, the other to what is left of a secondary main. Back in the early 1950s, the siding lead also became the beginning of a second main track that crossed Sand Creek, toward Denver ( the second track over the creek was removed in the late 1980s). In this case, though, the CB&Q (later BN, now BNSF) crossed the UP, giving more reason for the interlocking tower at that point. A "dummy" railroad crossing your track(s) would certainly emphasize the need for a tower, and would only take about a 3" strip of real estate. An interchange with the dummy road would not be necessary, but would provide an extra switching opportunity, and a way to transfer cars onto and off of the layout.
Happy Creating!
ASM

[davekelly]

I'd use it regardless. I think interlocking towers are plain "neat" and just scream "railroad."

[West Coast S]

Unless you have a considerable amount of conflicting movements onto those spurs/sidings, I would forgo the tower. Place some signals to govern the main and a phone box so the crew can call for permission to occupy the spur/siding, install derail switches and call it done.[2c]

Dave

[Anonymous]

Just joined... someone tell me how to post my own question? I like this one as it comes close to my own interest... I'm an ex-British Rail Signalman (Tower man)... I model US RR 'cos UK enthusiasts get too serious... also teaches me lots about USA. Our operating systems are pretty standardised... my research so far suggests US varies quite a bit.
In answer to this question...
I think that the same applies in the US as here... you get more installation for more traffic. The key is not how fast trains go but how long it takes them to stop and do things. One train a day doing 6mph doesn't need a whole lot...twenty plus trains and a linespeed of 70mph and you don't want to be pulling things up to tell them waht to do or for them to ask.
Anybody know any good books on Interlocking???

[davekelly]

David,

[#welcome]

To post a new thread, just click on the little folder "Post New Topic" at the bottom of each thread page.

[markpierce]

Thanks for your input. After considering your input and doing research on the local Southern Pacific San Ramon branch (1891-1978) (Irma Dotson's 1991 book titled San Ramon Branch Line of the Southern Pacific), I've concluded an interlocking tower would likely NOT be prototypical on my trackplan. This branch connected to its parent Southern Pacific twice: at its north and south ends, both with wyes. The north end did not have an interlocking tower, but the south end did have one.

The north end was at Avon, about three miles east of Martinez (Martinez is on the SP, now UP line from Oakland to Ogden via Donner Pass) on the Mococo Line which went east to the Central Valley via Antioch and Byron. (Mococo for Mountain Copper Company, Ltd, that was located nearby.) There was a small, one-story cottage type depot there from 1901 to 1964, located on the mainline at the west end of the wye.

The south end was at Radum, attaching to the SP's line between Niles Canyon to the west and Altamont Pass to the east. This mainline connected the South San Francisco Bay to the Central Valley. The Altamont Line eventually connected with the Mococo line east of Tracy in the Central Valley.

The San Ramon branch reached Radum in 1909 when SP extended the branch south from San Ramon. By this time the Western Pacific had built its mainline paralleling SP's Altamont Line. To reach the Southern Pacific track, the San Ramon branch had to cross the WP track at two places where the WP crossed two of the wye's legs. An interlocking tower was built within the wye at the west end in 1911. An SP community relations official said the SP had no record (about the construction?) of the Radum Tower and that the tower was jointly owned with WP. There was no depot building there, but an old baggage car was located adjacent to the tower and parallel to the mainline. In 1931 SP usually manned the tower six days a week (not Sundays) for eight hours: 7 a.m to 12 noon and 1 p.m. to 4 p.m. There were some periods when there was no towerman on duty. In 1940 it was manned between 9 a.m. to 10 p.m. six days a week except for meal breaks. When a towerman was not present and a train needed to cross the WP tracks, the towerman would be called at home or the signal maintainer, who lived near the tower, was to be called. There was a telephone located just north of the wye, and a 1988 photo shows a railroad phone next to the WP tracks. It is believed the tower continued in use until 1970 - 1973.

I concluded the tower in Radum was needed because the branch crossed the WP, and there was no tower at Avon because there was no crossing.

[Anonymous]

QUOTE: Originally posted by davekelly

David,

[#welcome]

Thanks for welcome and inf... working on it...
Have you tried "Smilie City?

[Anonymous]

Thanks for the update. What page are you on in Rand Mcnally?

Don't know if this helps...

In order to work those connections when not in an interlocking area ...Approaching the connection when connection facing (i.e. route ahead diverges)
the train would have to slow almost to a stop...
someone (fireman or a brakesman) would go ahead.
Contact controlling Dispatcher (if appropriate)
Get permission and a remote (electrical) release or unlock the groundthrow... [don't know if you used common keys or specific keys... latter would require collecting and returning before and after].
Work the groundthrow (and secure... so blades don't move under train)
Once the train has cleared the connection (is "safe inside") the Dispatcher will have to be re-contacted, the road reset and then the Dispatcher advised

With diesel/steam changeover period you will have caboose... so it would be possible for the conductor (or a brakesman) to reset the connection... this becomes more of a problem with no caboose... switch operator would have to wait for train to pass and reset switch and then walk back to head of train...you WALK on most Rights of Way I know of... running can cause the planet to get up and smack you in the face. This tends to hurt and delay the train.

The train would always have to wait while the crew completes the job on the ground and rejoins the train.

When the connection is trailing (i.e. the routes ahead converge)...

The train will have to stop dead short of the connection if it is set against the move while the procedure is gone through.

The train might drop off someone from the head end if no caboose or to save time... contacting the Dispatcher while the train draws clear.

Clearly, if the road is originally set for the train we are looking at drawing forward to a stand and then making a back-up move (setting back here).

Either way, if anyone has dropped off the head end, they can be picked up again with a backup move... otherwise above applies again.

This is where time keeps adding up if there is no interlocking.

I would certainly reckon that the WP lines across the wye would have added to the reasons for the tower in this case. There is more to get wrong where there are conflicting routes but no connections to tie things up mechanically.

One thing that happened here... during WWII a lot of connections, extra lines, depots and other stuff were added because of the massive rise in traffic... particularly ahead of D day. This meant many new Signal boxes (Towers) which were mostly either full time Block Posts (Keeping trains apart along length of line) or capable of being opened as Block Posts when needed. Something similar MAY have happened over there... where a military or any other depot opened... a new or additional connection may have increased the traffic level enough to require a tower... would the State have paid for it? ... or Washington? I guess the same applies with cold war installations...

[markpierce]

Thanks Dave. Avon and Radum aren't even shown on the AAA California regional maps. They are shown on topos, however. Avon is three miles east of Martinez, and Radum is on the immediate north border of Pleasanton. My topos show only railroad tracks at the immediate north and south ends of the former San Ramon Branch, so the maps were prepared after abandonment. The map does show a couple of industrial areas served by spurs immediately north of Radum.

Traffic on the branch was normally never particularly heavy. The branch was only built after local people donated land and money to "bribe" the SP. At the time of construction, the area was agricultural, shipping out mainly hay, grain, and later much fruits, nuts, and cream. At the time of abandonment, the area was suburbanized and produced no exports, but importing limited amounts of autos, machinery, and building materials. The SP extended the southern end of the branch at its own expense because of fears of WP expansion.

Trains were usually mixed passenger/freight in the early years. Until cars and trucks became common, there were two mail trains in each direction six days a week. (All trains originated in yards away from the branch.) Early in the century, trains for San Ramon originated in San Francisco. I believe trains from the north originated from Oakland. Mixed trains/passenger service ended in 1934. In later years I suspect freight trains originated closer to the branch, such as Port Costa in the north and perhaps Fremont from the south. Moguls (2-6-0s) and nothing larger than 2-8-0s ran on the branch during steam days. The last train was pulled by an SW-1500. McKeen motor cars were tried briefly in the teens, but were unsuccessful on the branch's 1% grades (steep enough for a run-away flat car starting in Danville to reach 60 mph on its way north to Avon.)

Perhaps the heaviest trains were the rock trains from the Kaiser gravel pits located immediately east of Radum. (These trains were the exception and orginated just feet from the branch's southern end.) In 1944 there were two 60-car loaded rock trains headed north daily over the San Ramon branch to be delivered to the Naval Weapons Station at Port Chicago (perhaps three miles east of Avon on the Mococo line) to build the docks and to the Travis Air Force Base (for its runways?) at Suisun on the Oakland/Ogden transcontinental line. The highest elevation was in Danville, about in the middle of the branch. The heavy trains required three steam locomotives to pull each train. In 1912 perhaps 120 cars of gravel and rock were shipped to Danville for use in building the new road to the summit of Mount Diablo.

[Anonymous]

Did you know that if a cut of cars "escapes" on one side of a valley there is no need to chase it... it will come back... most of the way... several times. just wait in the middle and put the brakes on when it's safe to do so. this is a lot easier than a cut of cars hitting the stops in a terminal and establishing that no-one had ever bolted them down properly. (Fortunatley this happened at night when the station was shut).

Thanks for information... stone traffic particularly interesting.


Thinking of which... and grades... if you have a suitable quarry on one of your lines... and a serious adverse grade... you might want a helper to get the trains out of the branch... this might be a switcher coming in to help from other duties nearby... or the loco off the local pickup goods... tie down the good on the other branch while the loco goes and helps the stone train out. When you have light traffic you can add interest by getting up to these things.

[markpierce]

The runaway flat car smacked an automobile (fortunately causing only minor injury to the driver) in Walnut Creek on its way north. With lots of street level crossings, a runaway car, with no horns and going 4 times faster than normal trains,can be very unpleasant.

[West Coast S]

Sacramento Northern operating rules mandated a locomotive on both ends of any train on the 4% grade through the Oakland hills. Seems a break in two occured enroute to Orinda and the wayward equiptment ran uncontrolled back downgrade to Oakland, scaring the bejesus out of automobile traffic and pedestrians on Shafter Ave before coming to a halt. No injuries or dammage resulted and the two locomotive policy was put in place place to keep it that way.

Dave

[markpierce]

I look at my completed interlocking tower, and David has a point! Yeah, during WWII there was a large increase in RR traffic at the junction, with several trains a day to develop and then to supply the military branch, as well as serving the older "civilian" branch. That could justify the contruction and operation of an interlocking tower at the junction, and it would continue to be of use in the post war years to avoid all that complication of trains entering and leaving the mainline to serve the branches.