Tower 12
Van Buren Street and Wabash Avenue, Loop

Service Notes:

Services:
	Green Line: Lake-Ashland-East 63rd
	Brown Line: Ravenswood
	Orange Line: Midway
	Purple Line: Evanston Express
	Pink Line: 54/Cermak-Loop

Quick Facts:

Established: October 3, 1897
Original Line: Union Elevated Railroad
Rebuilt: 1969, 1992-93
Status: In Use

Profile:

The location that is now home to Tower 12 and its associated junction was placed in service on October 3, 1897 to connect the South Side Elevated to the Loop Elevated. Tower 12 is located at the southeast corner of the Loop and controls a T-shaped junction, with the short two-block connector along Wabash and Harrison built in 1897 to connect the Loop and the old South Side main line connecting from the south.

So, why is Tower 12 called "Tower 12"? For administrative reasons that have now become unclear, the 11 stations and and three junctions on the Loop were assigned numbers beginning at the Van Buren & Fifth junction and counting up going counterclockwise around the Loop. The scheme progressed as follows:

No records have survived that indicate what numbers 1-7 were to be used for, although they may have been assigned to the Union Consolidated line west of Market Street, for which the company received a franchise but had no real intention of constructing. Another theory is that they were for the various stub terminal stations and junctions, and for the Met's Franklin & Van Buren station. In any case, these administrative numbers survive today only in the names of the two remaining original junction towers: 12 and 18.

The tower itself was a two-story affair set inside the junction between the various intersecting and diverging tracks, adjacent on the west of the southbound straight track. Its architecture was more practical than of any particular style, but did feature decorative window frames and sills, belt course moldings, and a hipped roof with a small chimney for the coal-burning stove inside. Entrance to the first floor was through a door at track level. Access to the second floor was also from outside, via a stairway on the exterior of the tower. The interior space was tight. With windows on all sides for maximum visibility, the tower was heated only by a small iron potbelly stove in the corner of the room. The junction was equipped with a hand-operated lever form of switch and signal control. This made the interior a dizzying array of levers and switches, all of which had to be precisely aligned by a vigilant towerman.

From 1900 to 1913, the track configuration of the junction remained largely the same. The Loop was operated as a railroad with left-hand running -- a very unusual practice in America -- a trait shared by two other "L" routes: the Northwestern Elevated and Lake Street Elevated. The Metropolitan and South Side elevateds started as and remained right-hand railroads, making the changeover to left-hand operation upon their entrance to the Loop at Towers 8 and 12, respectively.

In 1913, the Chicago Elevated Railways instituted crosstown service. With many North-South trains now through-routed, the configuration of Tower 12 would need to be changed. All Lake Street and Metropolitan trains still terminated around the Loop, as well as some night and off-peak Northwestern and South Side trains. Most North-South trains, however, went through and this required an extensive reworking of not only the Tower 12 interlocking but also Loop operating procedures. Just after midnight on November 3, 1913, all trains began operating in a counterclockwise, unidirectional manner, with Northwestern and South Side trains on the outer track and Metropolitan and Oak Park (Lake Street) trains on the inner track. North-South trains operated northbound via Wabash Avenue and Lake Street, while southbound they operated via Fifth Avenue (now Wells Street) and Van Buren Street. At the same time, the Northwestern and Chicago & Oak Park lines changed from left- to right-hand running to reduce switching delays at Tower 18.

The configuration of Tower 12 remained the same for the next 56 years, despite another crosstown route revamp in 1931 and the opening of the State Street Subway in 1943. Only small routing changes occurred. By 1936, the straight southbound track, not needed for revenue service, was removed, with only the eastbound-to-southbound track curving from Van Buren onto Wabash giving access to the southbound South Loop connector tracks. In 1943, Jackson Park-Evanston, Jackson Park-Howard, and Englewood/Normal Park-Ravenswood trains were rerouted into the subway, leaving the Kenwood-Wilson and Wilson-Loop rush hour trains as the only North-South trains running through Tower 12. In 1949, the CTA's^® North-South service revision brought some of these services back, with all Ravenswood and rush hour Evanston Expresses terminating on the Loop again. In the 1950s, Metropolitan Division trains were slowly siphoned off as well. Logan Square trains were taken off the Inner Loop in 1951 with the opening of the Milwaukee-Dearborn Subway. In 1958, Douglas and Garfield trains were removed from the Loop entirely and placed in a subway as part of the West-Northwest Route.

With only Lake and Ravenswood services left on the Loop at all times, supplemented by Evanston Express trains in rush hour, the Loop Elevated reached a low point in terms of intensity of CTA^® service. The CTA^® decided to begin removing some of the unneeded infrastructure in the 1960s. The North Shore Line interurban, which also used the Loop, abandoned service on January 21, 1963. Without North Shore Line trains continuing south from the Loop to Roosevelt Road station via the South Side Elevated, the elevated tracks that continued over Wabash south of the Loop were abandoned except for occasional nonrevenue moves. As a result, Tower 12 was removed from service on November 1, 1963, with the junction replaced with hand-throw switches. The tracks remained in place, however, and as of June 1964 the old interlocking tower still stood.

Only about five years later, the Loop experienced a renaissance with the opening if the Dan Ryan Line in 1969. The new Ryan line was through-routed with the Lake route, bringing a surge to the number of trains that would be using the Loop. The Lake-Dan Ryan trains would also only use the Lake and Wabash legs of the Loop, requiring some new track configurations at Towers 18 and 12, reactivation of the South Loop connector from Tower 12 to 17th, and the need to once again differentiate trains at Tower 12.

On September 28, 1969, concurrent with the beginning of West-South Route (Lake-Dan Ryan) service, the new Tower 12 interlocking was placed in service. Several aspects of the Loop operations also changed. The Loop returned to a bi-directional railroad, but used right-hand operation this time. Ravenswood trains operated counterclockwise on the Outer Loop at all times and Evanston Express trains operated clockwise on the Inner Loop during weekday rush periods. Lake-Dan Ryan trains took a straight route through the Tower 18 and 12 interlockings. This required a new southbound track straight through Tower 12 interlocking on Wabash to be laid. At the same time, the old eastbound-to-southbound curve from Van Buren onto Wabash was removed, terminated in a stub. It is likely that it was amidst these changes that the old two-story wooden tower was demolished, replaced with a simple relay house with a tower panel in the middle of the interlocking, adjacent to the southbound Lake-Dan Ryan track, where the old tower building was.

The black-and-white bar code-like ACI stripe (inset) is visible on Lake-Dan Ryan car 2231 at the 95th Terminal on July 4, 1971. For a larger view, click here. (Photo from the Joe Testagrose Collection)

With the addition of Lake-Dan Ryan Line, trains now needed to be differentiated from one another since they took different routes through the interlocking. Ravenswood and northbound Lake-Dan Ryan trains converged at Tower 12, but this could be easily accommodated by automatic operation of the interlocking aligning the switches for whichever arrived first. But Evanston Express and southbound Lake-Dan Ryan trains took diverging lineups at Tower 12 and had to be differentiated from one another. This situation only existed during rush hour, however, as the Evanston Route didn't otherwise come downtown leaving only Lake-Dan Ryan trains going south thorough Tower 12. Rather than man the tower during rush hours, the CTA^® decided to fully automate the interlocking. This was accomplished by means of a device carried by the trains that identified to the interlocking equipment what route to set. The device was a flat panel called an "ACI stripe", a vertical reflective stripe with black and white horizontal striping pasted onto the door leaf of the first door of the front of both sides of each Lake-Dan Ryan car. The black and white stripes were, in essence, a bar code that was read by the wayside scanner, which transmitted the identity of the approaching train to the interlocking and set the switches accordingly. If an ACI stripe was detected, the interlocking knew it was a Lake-Dan Ryan train. If no ACI stripe was detected, the interlocking set the switches for the default routing: Ravenswood northbound and Evanston Express southbound. If the stripe was not detected and the lineup was incorrectly set by the interlocking, a manual route selector mounted at cab height next to the track at the junction allowed the motorman to lean out his cab window and manually set the switch.

In later years, the ACI stripes were supplanted by the use of transponders, which emit a radio signal identifying the trains. Unlike the ACI stripes, the transponders were put on the Evanston Express trains and the straight-through route now became the default lineup. A transponder reader was located north of Tower 12 and let the interlocking know what type of train was coming. If no transponder was detected, then the switches are set for the default routing, which was for the Lake-Dan Ryan. If a transponder was detected, the route was set for the Evanston Express.

This 1971 view looking north on Wabash Avenue shows Tower 12 at center. Visible in the photo is the relay house in the middle of the interlocking and the remnants of the removed Van Buren-to-Wabash curve. For a larger view, click here [off-site link]. (Photo by Jet Lowe, courtesy of the Historic American Engineering Record, Library of Congress)

Few other changes were made to Tower 12 for many years. On November 24, 1981, the east-to-south connecting track from Van Buren onto Wabash, which had been removed in 1969 as part of the work to ready the junction for Dan Ryan service, was put back and placed in service. As the years went on the transponder system for the Evanston Express trains fell into disrepair and, with limited funding availability, CTA^® chose not to repair it. At that point, a towerman was assigned to man Tower 12 during weekday rush periods when the Evanston Express was running. Otherwise, the interlocking plant could be left on automatic, as there was no need to sort diverging routes when the Evanston Express wasn't running.

The next change to Tower 12 came when the Orange Line was being readied for service in the early 1990s. A new switch had to be added to the Tower 12 junction to allow northbound Orange Line trains on Wabash onto the Inner Loop westbound on Van Buren. This new switch was placed in service on April 22, 1993. This presented a new set of alternate routings that would take place at Tower 12 -- northbound Orange Line trains diverging west while northbound Green Line trains continued north -- that would need to be sorted out. It was still desired not to have to staff the tower at all times the Orange Line was operating, so a new set of transponders were installed. This set controlled the northbound routings from Wabash Avenue. The Orange Line trains carried transponders and a receiver was placed north of Roosevelt station. When the receiver detected a transponder, Tower 12 automatically aligned the switches for the Inner Loop. The default route was for the Green Line, which would be set to continue north on Wabash if no transponder was detected. Southbound Orange and Green line trains took the same lineup through Tower 12, so no sorting was necessary there. Southbound Purple Line (Evanston) Express trains did still need to be sorted out, but their transponder system was left disabled and a towerman continued to be assigned during weekday rush periods. The new Tower 12 interlocking, which also controls the diamond crossover south of Tower 12 at Congress/Wabash, was placed in service on March 14, 1994. As part of the new interlocking, a new "tower" was constructed on the east edge of the junction, cantilevered over the corner of Wabash and Van Buren. Actually just a small hut on an elevated platform, the higher location gave the towerman a better view of the approaching lines. The old relay house between the switches where the old tower panel had been remained in place as well.

Tower 12 saw a surge in traffic when the Pink Line service was inaugurated on Sunday, June 25, 2006. Pink Line trains operated clockwise around the Inner Loop and ran during all but owl hours. This meant that for the first time in decades, an "L" line would be taking the Inner Loop-around route at Tower 12 during all day and evening hours. Because of the increased number of trains trough the junction and the need to have a measure of human decision-making when routing trains, especially during rush periods, the CTA^® began staffing Tower 12 full-time concurrent with the beginning of Pink Line service.

Tower 12 junction as it appears today, looking north on Wabash Avenue on May 20, 2003. The elevated hut is the current tower, while the silver hut set between the switches was the relay house and local tower during the Lake-Dan Ryan days from 1969 to 1993. For a larger view, click here. (Photo by Graham Garfield)

	tower12b.jpg (68k) A view of Tower 12, looking north from the Congress & Wabash station circa the 1920s. A North-South train led by an 1100-series wooden control trailer turns off Van Buren on its way to the South Side. Note the differences from the photo at the top of the page: the surrounding buildings are taller and tall lampposts have been added to the elevated structure north of the tower. The similarities are just as telling. (Photo from the Fred Borchert/Robert Gibson Collection)
	cta4365.jpg (50k) A two-car Lake Street All-Stop train made up of 4000-series cars 4365 and 4366 passes through Tower 12 and turns north onto Wabash Avenue after leaving State/Van Buren station in June, 1964. Normally, Lake Street trains operated counterclockwise on the Inner Loop, but here the train is detoured onto the Outer Loop due to track work. (Photo by Jerry Appleman)
	060824pv.jpg (125k) [Off-site link] This 1971 view looks east from State/Van Buren station at Tower 12 and the curve from Van Buren onto Wabash as a Lake-Dan Ryan train crosses from the Loop into the South Loop Connector en route to the Dan Ryan Line. (Photo by Jack Boucher, courtesy of the Historic American Engineering Record, Library of Congress)
	060792pv.jpg (128k) [Off-site link] Tower 12 is seen looking east from State/Van Buren station in 1971. (Photo by Jack Boucher, courtesy of the Historic American Engineering Record, Library of Congress)
	060793pv.jpg (129k) [Off-site link] The curves in Tower 12 junction connecting Van Buren Street and Wabash Avenue is seen looking north in 1971 with the Adams/Wabash station visible in background. (Photo by Jack Boucher, courtesy of the Historic American Engineering Record, Library of Congress)
	tower12d.jpg (188k) Tower 12 junction is seen looking east on Van Buren Street on May 20, 2003. The elevated hut in the background houses the tower. The prefabricated buildings on the left and right house relays and other interlocking circuitry. (Photo by Graham Garfield)