By David Silver/photos as noted
The clattering of steel wheels against raised rails, the metallic shoonk of heavy mechanical levers being thrown, and the low hum and click of electrical relays and resistors — these are all sounds that can be heard at a diamond interlocking. More specifically, these are the sounds that were heard at Metra’s busy 16th Street Tower in Chicago, which controlled the interlocking switches and the immediate signals around the 16th Street diamond. Metra’s Rock Island District between LaSalle Street Station and Joliet crosses here from the north and south (railroad east and west). Amtrak’s Saluki and City of New Orleans, as well as various Canadian National freights, cross from the east and west. On an average weekday, there are around 120 moves taking place among the three carriers, with the majority being made by Metra. The morning and evening rush hours see approximately 75 moves. Nights are a bit slower with around 50 to 60 moves. In the early to mid-afternoon, there are also a number of light engine moves and wash moves made by Metra to and from its 47th Street Yard for cleaning and repairs between the rush hours.
An excerpt from the Electric Interlocking Handbook produced in 1913 by General Railway Signal and edited by Henry M. Sperry and Paul E. Carter states, “Not a single lever was in use in the United States, the first experimental installation having been made in this country by Messrs. Toucey and Buchanan at Spuyten Duyvil Junction (in what is now The Bronx in New York City), in 1874, and the first important installations on a commercial basis having been made by the Manhattan Elevated Lines of New York City with machines of the Saxby-Farmer type, built by the Jackson Manufacturing Co. of Harrisburg, Pa., in 1877–78.” This span of three or four years brought the advent of interlocking control towers as we know them today.
ABOVE: During the morning rush on April 11, Metra Train 611 crosses the diamond with a double-headed train with F40PH-3 111 in the lead. Metra movements to and from LaSalle Street Station account for more than 120 moves across the diamond each day. —David Silver photo
16th Street Tower was built in 1901 and placed into service in 1902, operated by New York Central at the time. The tower survived into the Penn Central era, but after the last former NYC passenger trains were moved to Union Station in 1968, control was handed over to the Rock Island. Here, the former Rock Island’s Joliet Subdivision crosses the St. Charles Air Line and Canadian National’s Chicago/Freeport subdivisions. In a single day, more than 120 Metra movements take place through the junction, compared to 10 CN moves and a handful of Amtrak trains.
The switch machine was custom-made by the Taylor Signal Company. Since its beginning, it has had pistol-grip switches, with General Railway Signal relays located in the ground level. The ground level of the tower also houses the signal maintainers. Some of the relays have maintainer stickers on them with writing dating back to the 1930s and 1940s, a testament to the good engineering of the time.
ABOVE: The massive pistol-grip-style machine was custom-built by Taylor Signal Company in 1901. Coupled with General Railway Signal relays housed on the first floor, this elegant machine has reliably controlled movements through 16th Street for nearly 125 years. The two silver cups and one red cup on top of the pistol grips are serve as a visual reminder to the operator that those tracks circuits are out of service that day. —Mark Llanuza photo
The Cutover
On the evening of April 11, 2025, decommissioning of the tower commenced, with control taken over by Metra’s Consolidated Control Facility (CCF) at 1501 Canal Street, which is located just across the St. Charles Air Line Bridge at BNSF’s 14th Street Yard, about a half-mile west of 16th Street Tower. During the morning shift on the final day, tower operator Sergio Matthews was working the levers. Matthews had been at 16th Street for nearly 13 years, having started with Metra in January 2012 and entering towers just five months later. After the changeover, he made the move a half-mile west to CCF.
In his time in the tower, the most complicated issues for Matthews were malfunctions and switch failures, as well as weather. “As long as I can move a train, it’s not difficult,” Matthews said. “When I move to CCF, there will be more territory and, therefore, more responsibility.” His move to CCF will expand to controlling the entire Rock Island District. Another thing mentioned — there are no real breaks, especially during the morning and evening rush hours. The tower operators are on their feet a lot, so time management and order of operation are key. With the move to CCF, the tower operators will be retrained to make the transition to dispatcher. They will be able to manage movements while sitting at a desk, all with the click of a mouse and the push of a button.
ABOVE: The signal engineers from Modern Railway Signal pose for a class photo. From left to right are Signal Engineer Jason Nates, Chief Signal Engineer Tom Hunter, and Signal Engineer Mike Weber. —David Silver photo
At approximately 7:30pm, a three-person crew from Modern Railway Systems — the company that installed the new signal bungalows at the interlocking —arrived to start the cutover process. The bungalows were built and assembled in nearby Mokena, Ill., by Metra employees. The crew consisted of signal engineers Jason Nates and Mike Weber, as well as Chief Signal Engineer Tom Hunter. Before work started, Hunter commented, “This changeover marks the end of operation of a structure that has been in service for more than half of the history of American railroading.”
At 8:00pm sharp, an entire crew of Metra signal employees, as well as the MRS crew, came together at the base of the tower to hold their safety briefing. Their authority to work ran from 8:02pm on April 11 to 4:00am the next day. Shortly after the safety meeting, work commenced in full. At 8:25, Metra Train 511 to Joliet became the last train to cross the diamond under a tower-operated signal. Moments later, the signals at 18th Street and at 15th Street displayed red “stop” indications in both directions. The signal crew immediately went to work on the switches, getting things ready in the signal bungalows, rewiring relays and welding new equipment into place…
