It's Electric! - The Westinghouse Brake and Signal Style L Frame

Every so often I mention the Westinghouse Brake and Saxby Signal Company which was the result of the British Commonwealth's Westinghouse Brake Company purchasing the then dominant UK railway signaling supplier Saxby and Farmer in 1901. For those of you who are unaware, George Westinghouse's claim to fame was the invention of the automatic railroad air brake and he set up corporate entities in both the US and overseas to market his produce. In an early example of corporate synergy, Westinghouse also became involved with railway signaling, either directly producing signaling hardware or owning a signaling subsidiary in many markets. Because there is little sense in reinventing the wheel, the Westinghouse corporate empire would cross-license signaling technology between its various arms. This is how US&S became the supplier of the Improved Saxby and Farmer type mechanical lever frame in the United States and how WB&SS Co would come to sell a power interlocking machine awfully similar to what would become the Model 14 family sold by US&S.

Balham Signalbox Style L Power Frame

As railway signaling moved from purely mechanical to incorporate automatic blocks, electric signals and power operated point machines, interlocking machines effectively became hybrids with both mechanical and electric locking. 19th century mechanical methods would continue to provide the route locking, while magnets and solenoids would lock the levers electrically based on track or switch position circuits. 

Electric locks on a traditional "armstrong" type lever frame.

Since safety critical railway signaling relays were quite expensive, signaling suppliers had an incentive to carry out as much logic as possible in the mechanical layer. Therefore even "power" interlocking machines like the GRS pistol grip style or US&S crank lever style still made use of miniaturized mechanical locking grids. 

Westinghouse owned Union Switch ad Signal had already been the North American licensee of the Improved Saxby and Farmer mechanical locking system and has been using it in its crank style power interlocking machines since the 1890's. In 1901 the newly minted Westinghouse Brake and Saxby Signal Company was suddenly in a position to employ US&S's innovations in Commonwealth countries and came out with its Styles A and B interlocking machines, localized for British signaling tastes.

WB&SS Co Miniature Lever Frame in British Service

Like the crank (ie "Model 14") style interlocking machines in North America, the Westinghouse power frames had three distinct logical components inside the box. First, a mechanical locking grid of the S&F type handling route locking. Second, locking magnets that would lock lever travel based on the state of the electric relay logic. Third, electric contact spindles that would make or brake electric circuits depending on the position of the lever. 

Style K frame with mechanical locking grid.

Style K frame contact spindles.

A route conflict would result in a hard lock as steel bits in the locking grid would physically block movement. An electric problem like points out of correspondence or an occupied track circuit would create a soft lock as the lever was stopped by magnetic latches interacting with a rocker arm on the lever spindle. Anyone who has visited HARRIS tower and its functional Model 14 knows the difference in feel between hard and soft.

Magnetic "soft" locks on a Model 14 machine.

All of this was fine until 1929 when the 23 ton weight of 311 lever London Bridge Style K interlocking machine made Westinghouse Brake and Signal question the sustainability of the technology. Unlike North American pattern machines, the British pattern was less lever efficient, needing more physical levers to carry out the same functions. This not only created a weight problem, but also a size problem as the locking grid dimensions grew literally by the square of the lever count. While American railroads had the space to build beefy towers with wide dimensions, the "early adopter" British railways had harder clearance constraints, especially in major cities where large power frames were most likely to be built. For example the aforementioned London Bridge signal box had to orient its locking bed vertically, making the tower an extra floor taller.

 

London Bridge Signalbox

The solution to this was the Style L frame. Externally the Style L looks exactly the same as the Style K, however internally it is quite different with the mechanical locking grid being completely done away with and replaced by electric locking. the Style L existed as yet another step between the purely mechanical interlockings of the 19th century and the all-relay plants that would ascend in the 1950's. However for anyone wondering why an electrically interlocked plant would even bother with clunky miniature levers, there are some advantages. First it maintains a familiar UI and reuses many of the components that were already in production. Second, it still reduces the number of high cost safety critical railroad relays. The latter is not entirely obvious, but an electro-magnet that unlock a contact spindle that a human then turns, is performing many of the same functions as a vital relay without the same need for precision manufacturing. The website covering Westinghouse power frames has both patent and part information so I'll leave digging down into the fine details of how this electric locking was carried out as an exercise to the reader. 

Style L parts

Style L restored

Style L relay locking logic

The Style L completely displaced the mechanically locked style B and K frames on the main line UK rail network with a burst of new deliveries being made to the British Rail Southern Region between 1948 and 1953. Additional frames were delivered to South Africa up until 1960 with a final BR frame delivered in 1962. An interesting ramification of the Style L all-electric logic was a far greater degree of adaptability than those with mechanical locking. In North America, all railroads (except naturally the PRR) had to hire US&S to perform major modifications to the mechanical locking grid. However the Style L electric locking could be modified without the need for specialized tools and British Rail was able to manufacture quite a few "new" Style L plants using left over components or even spare frames obtained for redundancy purposes during World War 2. Even after retirement from main line service, both heritage and miniature railways have been able to adapt surplus Style L equipment for their own track layouts.

 

The final act of the Westinghouse power frame would play out on London Transport in the form of the mechanically locked Style N and Style V frames as their modest lever counts and subterranean placement didn't trigger the same sort of weight issues seen on the main line railroads. In fact, the last Style V frame, think a Model 14 automated by pneumatic actuators) was installed on LT in 1993! (Which goes to show just how wedded the British were to mechanical technology.) With the closure of Wellington A Signalbox earlier in 2025 and Liverpool Lime St in 2018, the last active Style L outside of preservation might be the signalbox at Maidstone East, which was fittingly the last new built Style L delivered in 1962.

Another One I Missed: Conrail BRIDGE Tower Closed and Demolished

Up through 2019 Detroit featured what I would like to call the Iron Triangle of staffed interlocking towers, DELRAY, NS BRIDGE and (Conrail) BRIDGE. As you might guess the latter two involve movable bridges over the River Rouge. In November 2020 I covered the closure of DELRAY tower as the last active long lever interlocking machine in North America, however I was then unaware that Detroit's iron triangle had already been broken with the closure of Conrail BRIDGE tower in late 2019. I'll blame the COVID era for it taking 6 years for me to notice the unfortunate change in circumstances, but I am going to post about it nevertheless so people don't have to sort through Facebook groups to learn what happened.

Conrail's BRIDGE tower benefited from a perfect storm of circumstances that saw it last well into the 21st century as an active block and interlocking station. First it was attached to a movable bridge, a thing that until recently required human presence, and second, it was part of Conrail Shared Assets, which is a 50/50 joint venture between NS and CSX creating a "Port Authority" type situation where slight inefficiencies can persist. Moreover, when FN tower in Trenton, MI closed around 2003, the operator at BRIDGE was given control of that territory becoming a mini-dispatcher of the Conrail SAO Detroit Line. This situation is similar to the operator at UPPER BAY tower in Conrail SAO's New Jersey division being assigned additional interlockings over the last 20 years or the CSX/Conrail operator at the Livingston Avenue Bridge acting as a mini-dispatcher for the Amtrak Albany Terminal (until Amtrak re-signaled the area around 2018).

BRIDGE had previously survived one brush with re-signaling around the time of the Conrail split where its S&F lever frame was replaced by a more modern unit function type panel. The efficiency movement finally caught up with BRIDGE in late 2019 with the tower being closed and then demolished between August 2019 and November 2020. The BRIDGE drawbridge was likely being placed under remote control as was the style with several other Conrail SAO operated movable spans at as of late. With DELRAY closing in 2020, this left NS BRIDGE, aka NS ROUGE BRIDGE aka ECOURSE JCT as the last remaining staffed traditional tower in the Detroit area (although in theory the drawbridges connecting Zug Island to the mainland also count as towers).

While not as iconic or as accessible as DELRAY, BRIDGE was still the second best example of an interlocking in the Detroit metro area. It's another sad loss in a city that hosted diverse mix of active and disused towers well into the 1990's. 

METRA's 16TH ST Tower to Close, Following CY

I just got word that METRA's famed 16TH ST Interlocking tower at the triple crossing of the Alton (CNIC), Saint Charles Air Line and the Rock Island, is slated in close in early April. Built in 1901, the tower and its original Taylor Model 2 pistol grip type interlocking machine have been in continuous service since 1901 or 124 years! Unlike some other towers where the closure comes out of left field, this one has been telegraphed for some time. 16TH ST (and presumably its interlocking hardware) has been falling into increasing disrepair and I am honestly shocked it did not manage to catch fire or fall down on its own.

16TH ST in 2017, it looks worse now.

Cost cutting on the part of Canadian National, starting in 2019, have reduced the 12 diamond plant to just 4, as what had been a Y split of two double track main lines crossing another double track main line, was reduced to two single track lines crossing a double track line. It was clear for some time that once all the work was finished to rebuild the complex crossing to some sort of new standard, the tower would be closed.

Given the wooden tower's condition, its also pretty clear that the tower is beyond saving, even in situ, but I'd expect parts of the interlocking machine and model board to make their way into preservation similar to what we saw with CALUMET about a decade ago. Anyone looking to grab some photos during the final days in service can snag a view from the corner of 16th St and Clark.

In other bad news, the late model Chicago Northwestern CY tower has also been closed by Union Pacific as a downstream outcome of UP looking to transfer METRA commuter operations to METRA itself. The operator at CY had control of the local interlocking and much of the METRA UP-Northwest line, where Metra was the primary source of traffic. This was likely a way to better allocate the costs of dispatching the line. Run from a video display interface for years, control might end up in the METRA operation's center with staffing of the still open LAKE ST tower, also taken over by METRA.

Unlike 16TH ST, CY is of far more sturdy construction and will likely serve as an maintenance base for decades to come like its sibling KEDZIE tower on the UP-WEST line. With these two closures the Chicago area will be reduced to four traditional interlocking towers on main line railroads, LAKE ST (CNW), TOWER A-2 (Western Ave), TOWER B-17 and JB.  Three of these towers are on the METRA UP/CNW-West Line between the CNW Terminal and West Chicago with the fourth being on the Milwaukee West Line.

The River Line's Last Conrail Signals - Part 1

Over the years I have reported on the CSX re-signaling efforts on the former Conrail River Line along the west side of the Hudson River. These efforts go back to the early 2000's as CSX looked to increase capacity on the route after its takeover and culminated in the recent re-signaling of CP-SK in Selkirk, NY.  CP-SK was able to hold out as long as it did because it was itself completely re-signaled by Conrail immediately before the CSX/NS split, dropping the need for capital improvement way down on the list. However for those Hudson Valley Conrail fans looking to get signaling fix, two small islands of Conrail era signaling remains. 

Back in the 1960's, the old West Shore route was given a healthy dose of efficiency by the innovators at the  New York Central, changing a double track line into a single track with passing sidings spaced every 10 miles. This budget CTC system featured single block, restricted speed passing sidings about every 10 miles and fit in with the decline in northeast freight traffic, especially after the Penn Central and Conrail was able to divert traffic away from the former NY Central main line and the West Shore Route. However, as intermodal traffic picked up in the 1990s, Conrail found its River Line under capacity as every pass would require a painfully slow restricted speed pull-in.  Therefore it began to signal the sidings and modify the old New York Central small target searchlight signals to support Medium speed diverging routes, generally working south to north.

Just prior to the CSX takeover in 1999, Conrail was largely finished with this project, however for whatever reason the old passing siding between CP-104 and CP-106 was found to be lacking and the siding was expended a little over a mile to the south to a new CP-102 with CP-106 also being completely rebuilt. In the same project,  the siding at the southern end of the line from CP-22 to CP-24 was extended to a new CP-26. In a manner similar to CP-SK, CSX put replacing both these patches of late model Conrail signaling low down on the priority list and today these two sidings and some adjacent intermediate signals are the only remaining Conrail signals on the River Line. Here in Part 1 I will cover the northern island with CP-104, CP-106 and the intermediate at milepost 100.

With CP-106 directly adjacent to US 9W just south of Catskill, NY and CP-102 behind the quaint West Camp, NY post office, both locations are generally accessible and equipped with two Conrail target type color light masts, a 3-lamp Safetran dwarf stack, CorTen weathering steel relay huts and those iconic blue station signs.

The the 1008/1009 automatic signal, distant to CP-102, is just south of the Malden Turnpike grade crossing at River Line milepost 102 and also pretty easily accessible. This one makes use of premium US&S target type color light signals as opposed to the Safetran signals at the two interlockings.

In a future Part 2 I'll throw up some photos of CP-22 and CP-26 the next time I find myself driving to Upstate NY or New England. It's highly likely that CSX will also replace all these signals whenever some manager happens to notice the non-conformity. Moreover, without their presence there would not be much stopping CSX from a wholesale change in signal rules on the River Line from Conrail to Seaboard, so get out there and get your photos of R/*Y* Medium Approach while you still can. 

Last Traditional Signalbox Closes in New Zealand

Word has come down that Wellington A Signalbox has closed. Constructed in 1937 in conjunction with the Hutt Valley 1.5kv DC suburban electrification scheme, Wellington A Box was was not only the last full time staffed signalbox in the Wellington suburban network, but also the last traditional signalbox of any kind in the country (although it's implied that part time signalboxes might still exist). Corner cases aside, this marks the end of a 25 year long transition from a network with numerous staffed signalboxes containing both "power" frames and unit lever CTC panels.

With signaling system essentially in alignment with the American method, New Zealand was a fun house mirror of signaling equipment that was just a little bit different than its North American counterparts. Unfortunately, just like was seen in North America, New Zealand implemented several national railway "investment" schemes that swept away the old cast iron searchlights and signalboxes and replaced them with LED color lights and signaling centres with video display interfaces. I had previously covered two phases of this transition with the closure of PETONE signalbox in 2013 and ADDINGTON signalbox in 2016. Although re-signaling efforts had slowly chipped away at Wellington A signalbox over the years, the terminal interlocking at one of New Zealand's busiest stations was able to hold on in a similar fashion to CNW LAKE ST in Chicago. In another parallel to LAKE ST, Wellington A signalbox contained a fairly large all electric power frame of the Westinghouse Brake and Signal Co "Style L" variety, which is essentially an evolved British pattern US&S Model 14 machine that dispensed with the mechanical locking grid in favor of electric circuit based route locking via the usual US&S pattern locking magnets.

Covered in great detail on the WB&S Co power frame website, Wellington A box was built with three separate Style L frames, a 67-lever console in the center and two 31-lever consoles on either end. Later the left console would be replaced by a unit lever CTC panel. Dave, the webmaster of the now defunct Valley Signals page, provided his own extensive coverage on the final decades of Wellington A Box, now available via Archive.org.

Kiwi Rail was thoughtful enough to post a couple of Youtube videos profiling the signalbox, the Style L frame and the remaining operators that worked it. While the miniature "armstrong" levers look very British, its important to understand that these are essentially US&S style crank levers set vertically and rotated 90 degrees. You can see in the photos and video the familiar spindle type electrical contacts below the levers with the locking magnets out of sight behind. In addition to the official video is another one that seems to have been produced for local media with a bit more detail and external shots.






While I said this was (likely) the last operational traditional signalbox on the NZ rail network, the Keirunga Park miniature railway is signaled from a local signalbox equipped with another WB&S Co Style K power frame donated by New Zealand railways in 1985. To the extent this "counts" is left as an exercise to the reader, but it offers a preservation experience on par to that of HARRIS tower in the United States. Anyway, check out the linked resources before they to go out of service.

Valleysignals.org.nz Fades Into History

While performing research on an upcoming post I regrettable discovered that the excellent Hutt Valley signaling website (aka Valley Signals) has gone offline with the domain, valleysignals.org.nz, now pointing to a reseller. Although focused on the specifics of signaling in Hutt Valley north of Wellington, it provided extensive detail on NZ signaling in general including the change from the relay to solid state era between 2001 and 2013. With photos, signal diagrams and quite a bit of inside information the Web 1.0 era site gave visitors all the necessary information with little fuss.

Originally hosted on Trainweb, it long ago moved to its own hosting and domain. Around a decade ago it backed up my own coverage of PETONE signalbox during its last few months of operation. Along with other web 1.0 websites like Blockstation.net and Mark Beij's signaling site (hosted on the defunct Keystone Crossings), it was easy to assume they would be be online forever. Unfortunately those with enough life experience to self-host websites in the 1990's and early 2000's are rapidly approaching the age where their heirs will be getting the emails about domain name renewal. 

Valley Signals Webmaster in 2013

From what I have gathered, the individual behind Valley Signals, who apparently went by Dave, started the site in 2001 as a way to document all aspects of railroad and railroad signaling history in the Wellington, NZ area.  The site was fully fleshed out over the following three years with regular updates through 2013 when Kiwi Rail implemented a major re-signaling project in the Hutt Valley, wiping out most of the relay based signaling. Unfortunately in a 2019 "site status" blurb, he mentioned having lost all interest in railways as of 2016, but had decided to keep the site up with some additional sections on his more personal interests. By 2023 the domain had lapsed. As we can see from the photo above the owner appeared to be at least in their 70's or 80's as of a decade ago. This unfortunately does not bode well for trying to rescue the site in an official capacity and because their contact info (e-mail) was based on the valleysignals domain, there is no longer a way to reach out.

The webmaster waving to the last train signaled through PETONE signalbox.

The good news is that the Wayback machine seems to have preserved most of the site contents and because the site was so static for so long, there was ample opportunity for it to be scrapped multiple times, so if you get an error for pages on the most recent dates, you can go back to 2013 without loss of content. Using this resource I was able to restore all the links on my PETONE signalbox page. Still, given the Internet Archive's own legal issues I will make an effort to save out as much of the Valley Signals content that I can. Despite the webmaster's assumed passing, if anyone knows what happened to the person or persons behind Valley Signals, please let me know as I might have some options to get a more official mirror back up and running.

DOCK Movable Bridge to Become DOCK Bridge

In 2017 the great DOCK tower closed as a staffed interlocking station after about 80 years of service. However the imposing structure retained one last official duty beyond "employee lounge" and that was housing the controls and auxiliary equipment to work the adjacent three span vertical lift drawbridge situated between the tower and Newark Penn Station.

 

Unfortunately the Passiac River was not the industrial thoroughfare of years past and unlike the nearby PORTAL bridge whose low clearance made it subject to periodic openings for barge traffic, the height of the DOCK draws is sufficient for the dwindling commercial traffic on the waterway.  After not opening a single time in 2024, Amtrak has petitioned the Coast Guard for permission to permanently close the bridge.

While it is unlikely that anything will happen to the bridge, Amtrak will no longer have to maintain the operating equipment, interlocking logic and the mechanisms used to make and break rail and overhead wire continuity.

DOCK draw actually contains three independent movable bridge spans. A large 3-track north span for mostly westbound Amtrak and NJT trains, a 2 track span for PATH rapid transit trains and a single track span for mostly eastbound Amtrak and NJT trains. The PATH span was set at a higher clearance above the river to reduce the number of openings on what was higher frequency rapid transit line.

 

One interesting quirk was the use of standard point machines to work the rail locking mechanisms at least on the PATH tracks. 

Based on the general interlocking layout I would not expect many signals to move, although the eastbound signals on tracks 2 and 3 might be moved across the bridge to resolve possible ACSES positive stop issues.

The fate of the control equipment on the operator's level and the auxiliary equipment, like AC-DC motor-generators, on the cavernous ground floor remains to be seen, however the safe option would be to leave it in place just in case. Numerous lift bridge have been converted to a fixed status with the counterweights left to dangle for many decades with little thought.

The petition requires a 120 day trial period of being "closed" at which point it will be approved or denied. After that there would be no set timeline for Amtrak to make changes so if a signal move looks likely I'll keep you informed.