The original Montrose Tower is seen on the left, looking north across Montrose Interlocking in the mid-1910s. The tower controlled two access points to Lower Wilson Yard -- switches to a two-track ramp diverge off to the right, while directly in front of the tower is a one-track incline down to the lower yard, later removed -- as well as into the south end of the Wilson upper yard. Wilson Shop is in the background. For a larger view, click here. (Photo by Frank M. Hollenbeck, courtesy of the Krambles-Peterson Archive)

Montrose Tower
Montrose Avenue and Kenmore Avenue, Uptown

Service Notes:


North Side Main Line

Quick Facts:

Established: 1900
Original Line: Northwestern Elevated Railroad
Rebuilt: 2020
Status: Planned



There have been two different interlockings at Montrose on the North Side Main Line during two different periods.

Layout of Montrose Interlocking in 1913. For a larger view, click here. (Reprinted from Instructions to Trainmen in Connection with Through Routing, issued by CER to employees in 1913, Graham Garfield Collection)

The original Montrose tower and interlocking were located at Montrose Avenue, between Wilson and Buena stations, at the south end of Wilson Yard. The interlocking plant at Montrose controlled access to both the south end of the elevated (or "upper") Wilson Yard, as well as movement of trains to and from Lower Wilson Yard. The switches in the interlocking plant consisted of turnouts from track 2 (southbound express track, post-1913) and track 4 (northbound local track, post-1913) to a two-track curved alignment that skirted the south side of the yard, providing a switch into the upper yard and a two-track line on an incline down to the lower yard. In addition, north of these main line switches there was a turnout from track 4 directly into the upper yard, and a switch that connected a second, one-track incline from the lower yard alongside the west edge of the mainline, connecting into track 1 southbound. The plant was completed with a set of crossovers on the main line -- a left-hand crossover between track 1 and 2 and a right-hand crossover between track 3 and track 4 -- at the south end of the interlocking plant to allow trains to switch tracks approaching or coming off these yard leads.

A two-story tower building was located on the west side of the main line right-of-way, on the south side of Montrose Avenue, cantilevered off the elevated structure. The building itself was fairly utilitarian in style, a sheet metal-clad two-story building with a hipped roof.

The interlocking plant it controlled was mechanical, with the switches and wayside semaphore signals controlled by large levers in the tower that were connected through a "locking bed" to a series of rods along track level that manipulated the switch points and signal arms. The locking bed consisted of steel bars forming a grid constructed so that, if the function controlled by a given lever conflicts with that controlled by another lever, mechanical interference is set up in the cross locking between the two bars, in turn preventing the conflicting lever movement from being made.

A second, similar tower at Wilson, a new blocks north, controlled access to the north end of Wilson Yard, as well as in and out of the Wilson terminal station.

Sometime between 1913 and 1949, a series of changes was made to Montrose Interlocking. The ramp between the lower yard and the main line connecting at Montrose was removed, in favor of a new incline connection between a separate freight interchange track west of the main line and the lower yard. In addition, the switch directly from track 4 into the upper yard had been removed, and the left-hand crossover between tracks 1 and 2 at the south end of the interlocking had become a right-hand crossover (making for a pair a right-hand crossovers here, between tracks 1 and 2, and between tracks 3 and 4).

Effective August 1, 1949, the new CTA enacted a restructuring of service on its north-south lines, and as part of this passenger trains no longer used the Lower Wilson station. As such, train movements on and off of the incline to the lower yard were reduced to equipment moves, though in the short term the lower yard continued to be regularly used, so Montrose remained interlocked and tower-controlled. It is likely that, around this time, staffing of the tower was reduced, as was the case in many locations around the "L" system as the CTA looked to streamline operations and reduce labor costs, and was the case at Montrose's sister tower at Wilson at the north end of the yard. However, when this may have occurred and to what degree is unclear.

As usage of and frequency of movements in and out of the lower yard decreased, the need to have two connections to it, let alone a tower-controlled, interlocked one, was severely diminished. Sometime between December 1951 and November 1952, the two switches from the main line to the incline to the lower yard were removed, and the ramp was removed from service. By the same time, the two right-hand crossovers (between tracks 1 and 2, and between tracks 3 and 4) were changed to hand-throw switches. At this point, Montrose Tower appears to have been out of service. It was demolished sometime thereafter.

The two manually-operated right-hand switches remained the status quo at Montrose for the next 40-plus years.

Circa 1996-97, a decision was made to revamp the interlockings at Wilson and at Armitage, both to renew the track and signal infrastructure as well as to rationalize the layout of the switches to make these interlockings more useful. The layout of the switches at Wilson (as well as at Armitage) were reconfigured to be a giant X, allowing for movement between any of the four tracks. The layout at Wilson consisted of a universal crossover (a set of left- and right-hand crossovers) between tracks 2 and 3 south of Wilson station (actually located between Sunnyside and Montrose avenues, interlocked and controlled from a new Wilson Tower. The layout was completed with four hand-throw switches -- two north of the new Wilson interlocking and two switches south of Montrose Avenue, where the two switches remaining from the old Montrose Interlocking remained. Circa 1997, these two old hand-throw right-hand crossovers at Montrose were removed, replaced with a right-hand crossover between tracks 2 and 1, and a left-hand crossover between tracks 4 and 3; these two switches at Montrose were hand-throw, not controlled by the new Wilson Tower.

These Montrose crossovers remained in service until 2020.


A New Montrose Interlocking

As part of the CTA's Red-Purple Modernization Program (RPM), a new interlocking is planned to be installed at Montrose. RPM's Lawrence to Bryn Mawr Modernization (LBMM) project includes replacement of the four-track embankment between Leland Avenue (south of Lawrence station) and Ardmore Avenue (between Bryn Mawr and Thorndale stations) with a new elevated structure, which would be built in halves (referred to as Stage A and Stage B by the project) so that two tracks can remain in service through the construction zone at all times. To achieve this, new interlockings are needed at the north and south ends of this zone to merge and sort trains transitioning between the 4-track and 2-track zones.

The interlocking at the south end of the LBMM area will be at Montrose Avenue. The new interlocking will include three diamond crossovers -- one between tracks 2 and 3 at the north end of the interlocking plant, and a pair between tracks 1 and 2 and between tracks 3 and 4 at the south end -- and a new tower.

The plan also includes the decommissioning of the existing Wilson Interlocking and removal of those two interlocked switches as well as the two existing hand-throw switches near Montrose, preceding the installation of the new switches, which will be in generally the same area as the old specialwork.

Construction of the new Montrose Interlocking is planned to occur in 2020.