ALTO: One Tower, Four Roads

This article originally appeared in The Trackside Photographer in November of 2018.  It builds on my previous coverage of ALTO tower posted in 2011 with additional photos taken in 2012 and 2018 and additional reference materials that I had obtained during the intervening years.

ALTO (JK) tower, in Altoona, Pennsylvania, was built by the Pennsylvania Railroad in 1915 and remained in service for the next 97 years, closing in 2012. Over that time it worked under the auspices of four different railroads, the PRR, Penn Central, Conrail and Norfolk Southern and each railroad, in turn, brought something new to the table. It is easy to think of railroad history over the last century to be one of subtraction, infrastructure being removed as a transportation monopoly yielded to competition from air travel and highways. However, for at least it's 97 years in service, ALTO's story was one of adaptation to the ever changing times.

ALTO tower in 2012 as a pair of NS helpers push past.

What did the PRR bring to ALTO? A simple answer is wealth. The PRR was something like the Google or Amazon of it's day, a technological pioneer with the deep pockets to afford more than the basics. The wooden construction wasn't a cost cutting measure, but actually a mark of the PRR's dynamism as up into the early years of the 20th century the railroad's constant re-investment would render interlocking towers quickly obsolete, requiring frequent replacement. In fact the odd pop-out on the east side of the tower was added  when the original interlocking machine proved to be insufficient and a two more had to be installed in the 1930's. On the front of the tower, the bay window was an optional extra that gave the tower staff an unobstructed view of the Main Line, reducing delays and operator error.

Extensible wooden construction.

Although ALTO's design had a degree of implied disposability, the PRR nevertheless spent money on architectural flourishes such as the fish-scale siding, the shade over the relay room windows and the wheel-like ornamentation.

Transportation themed ornamentation.

To control the train movements at the west end of the busy Altoona passenger station and the freight yard, the PRR invested in an early style of Union Switch and Signal Electro-Pneumatic interlocking machine with 27 levers. In 1915 this type of machine was typically seen only in major urban junctions and station terminals like New York's Penn Station, but the PRR had no compunction against installing a very expensive piece of technology in what might otherwise be a "temporary" interlocking tower given the railroad's uniquely heavy traffic density. Still, the PRR was no spendthrift and had a penchant for building slow speed interlocking plants in busy terminal areas. Since trains were going to be making station stops, changing power or having helpers attached little was lost in having all trains move through the interlocking at 15 mph with the advantage of vastly simplified interlocking logic and compact dwarf signals.

Original 1915 US&S "EP" style interlocking machine.

Although by 1915 most interlocking arrangements in North America made use of track circuits and other forms of non-mechanical logic, "armstrong" style lever frames with mechanically worked switches were still the norm as they reduced the number of the highly expensive relays and could also be run on battery power. Situated in the PRR's own company town, the road had no problems supplying ALTO with a full time source of electricity.

Rear of the 27 lever EP machine.  The glass top is protected by a canvas mat.

 

When built in 1915, ALTO, (named JR until 1942), tower was fairly unremarkable as it was simply one of *six* towers located in about a two mine stretch in downtown Altoona. From the east Main Line trains would pass WORKS tower at the Juniana Locomotive Shoppes while trains emerging through the yard would pass through SOUTH tower's plant. The east end of the passenger station was control by 10TH ST tower while the west end of the station was control by 14TH ST. Directly abutting 14TH ST's territory was ALTO, where trains from both the yard and Main Line would be preliminarily sorted onto about 6 tracks moving towards SLOPE tower. SLOPE would preform final sorting into the regular Main Line configuration of 2 single direction ABS in each direction.

1951 vintage low speed ALTO interlocking layout.

 In 1933 the 11 lever interlocking machine from 14TH ST tower was transferred to ALTO with the 23 lever machine from 10TH ST tower arriving in 1935 and creating the aforementioned bump-out on the east side of the tower. The new machines were re-numbered as part of a single unified interlocking plant with 61 levers. 

14TH ST interlocking machine moved to ALTO in 1933.

Another addition from the PRR was this steel lattice signal bridge. While many railroads would make do with cantilevers, bracket masts and dwarf signals, the PRR never shied away from spending on full signal bridges, even if they only mounted signals for a fraction of the tracks spanned. As ALTO was a slow speed plant, the only the two westbound Main Line tracks needed "high" position light signals, which would at best display Approach Slow.

ALTO's westbound 6-track signal bridge.

The PRR most likely upgraded the ALTO plant from semaphore signals to position light signals in the 1930's along with the territory expansion with the signal bridge having been part of the process. However, the design of the signal bridge, which uses less steel and more lattice, tends to imply an earlier vintage.

By mid-century the PRR had gone from being at the forefront of new technology to becoming somewhat conservative. In the realm of signaling this meant a continued faith in manned interlocking stations and Automatic Block Signaling as opposed to Centralized Traffic Control. So when traffic levels declined and operations in the Altoona terminal changed, SLOPE interlocking was drastically simplified and its tower closed with control being transferred to a small unit lever panel inside ALTO in an updated process operationally similar to the way the other two complete interlocking machines had been transferred 20 years before.

SLOPE interlocking control panel.

In 1968 the Pennsylvania Railroad merged with the New York Central to form the Penn Central Transportation Company. Quickly falling into bankruptcy by 1970 the new railroad struggled to maintain operation and invest in it's physical plant. However, 1973-74 the Altoona terminal was the beneficiary of some of the PC's limited capitol budget. A number of towers were closed with their functions being transferred to a Union Switch and Signal panel inside ALTO tower. This gave the operator at ALTO effective control over the entire Altoona terminal.

Altoona Terminal CTC machine.

By the 1970's steam power had long since vanished from the scene and passenger operations were also dwindling. Fewer trains needed to stop for helpers to be added and the slow speed interlocking plant had become a bottleneck. To relieve this problem and to reduce costs, ALTO was rationalized with unnecessary tracks and turnouts being removed, including the entire east end of the passenger station along with the 27 lever 10TH ST machine that controlled it. The interlocking was also converted to full speed operation with high signals replacing dwarfs on main tracks. To this end the Penn Central installed a new intermediate westbound signal bridge with three high position light signals bolted on top. Gone were the days of crafted steel lattice as by the 1970's plain steel beams were the name of the game.

The "famous" Penn Central vintage ALTO signal bridge.

The rationalization resulted in a new model board made from plastics and other "modern" materials. Instead of hand painted labels, a consumer grade label maker stepped in to do the job. The Penn Central layout featured two bi-directional main tracks and two yard leads from the east and three main tracks (one bi-directional), a yard lead and a spur track from the west. Within ALTO interlocking two pocket tracks were created for helper sets to lay over while waiting to coupling onto trains headed up the grade.

In place of the slow speed dwarf signals high PRR Position Light masts with "red eyes" on the upper horizontal position and a full size backing plate on the lower head (both Penn Central innovations) appeared. These masts were installed on the newly bi-directional track 2 in the eastbound direction and on tracks 1, 2 and a yard lead in the westbound direction and allow for movements to proceed at track or 30mph diverging speeds. Of course to get those higher diverging speeds a number of the switches were upgraded from #10 points to #15.

Straight shots on tracks 1 and 2 under Clear signals.

From the ashes of the Penn Central rose Conrail and along with it billions of dollars in government funding. In the early years this meant bringing the existing physical plant to a state of good repair. Wooden structures need paint and along with the other PRR Main Line towers, ALTO was no exception. Still, there was a lot of old railroad spirit, and management, in the Conrail organization and as a result ALTO was painted with a gray and blue scheme, still visible here in 2004.

Time to call Sherwin Williams

ALTO was also given a new nameplate made of reflective materials in Conrail white and blue.

The aging double hung windows were also boarded up and replaced with cheap pre-manufactured windows one might buy in bulk at a hardware store. While Conrail could splurge on a bit of paint, trying to restore 1915 vintage windows was beyond the scope of the railroad's signal department.

Available in 10 packs at Lowes.

Conrail also brought us ALTO's final configuration in conjunction with the Altoona Transportation Center project in the late 1980's. The direct crossover from track 1 to track 2 westbound was removed so westbound trains on track 1 or out of the yard had to use the western ladder track. Westbound trains on track 2 could switch to track 3 east of the main interlocking or continue straight on track 2.

ALTO interlocking exhibits a distinct rightward slant.

The Altoona Transportation Center project that extended the passenger platform not only forced the elimination of the 37 switch from track 1 to track 2, but also reduced the space available for signals causing the Penn Central era westbound masts to be replaced by two PRR pedestal type signals and a dwarf. Reduced use of helpers as diesel engines became more powerful prompted Conrail to operationally eliminate the track 3 pocket track by signaling through trains directly from track 2 to track 3 over the 31 switch, instead of running them past the tower to cross over via the 1 switch.

Grey weather is the position light's time to shine.

In 1999 the Conrail's Pennsylvania Railroad legacy, including the PRR Main Line and ALTO tower, was sold to Norfolk Southern. For a number of years nothing happened, but then around 2006 NS fixed the roof and applied a fresh coat of paint. The paint scheme was a uniform grey, but it showed that NS had no immediate plans to close or demolish the tower.

Of course "immediate" is a relative term. In 2011 a re-signaling project for the entire Altoona terminal was initiated and in 2012 it was completed with the tower closing after 97 years. In the case of ALTO, the interlocking plant wasn't simply re-built, it was completely removed, replaced by a plain Jane 3 track crossover named CP-ALTOONA that takes up the space once occupied by CP-SLOPE. Here we see the new three track westbound cantilever mast being installed in 2011. Unlike the 1915 signal bridge it is made from thick tubes of mass produced aluminum with only a fraction of the labor. Unlike it's predecessors, the new hardware will not be changed through time, but simply replaced and re-purposed. In fact due to some signal changes in 2018 a new, new cantilever is already schedule to replace the one installed just 6 years before.

With Altoona Yard a shadow of it's former self and freight trains becoming longer and heavier, it was no longer practical to stop long trains on the grade to attach helpers waiting at ALTO. In fact the helper pockets had been largely unused for years before the closure as through trains stopped elsewhere on the main line for helpers to tie on or cut off.

Going, going, gone.

The story of ALTO tower and interlocking was one of continuous evolution, always changing with the times to remain relevant until one day it found that it's whole reason for existing had completely vanished, seemingly overnight. It's not just that manned towers have been replaced by remote offices. It's that quirky interlocking plants hand drafted by some Victorian era railroad savant have been replaced by lost of straight lines laid out in CAD and cut into the earth by mechanized construction equipment. It's a world where evolution is no longer necessary because it is more efficient to just start over from scratch.