CTA highlights successful Loop outage to replace Tower 18 castings

Chief Infrastructure Officer Bill Mooney told the board the agency executed a major weekend outage (Oct. 25–27) to replace worn castings at Tower 18 — the key interlocking at Lake and Wells that routes trains through the Loop. The castings are custom-formed components that allow multiple interlockings to operate; staff observed cracking after 15 years and nearly 1,000 daily train movements.

The operation required rail-borne cranes to lift castings that weigh thousands of pounds, extensive lock-out/tag-out procedures, a full service bulletin and substantial bus-support routing. The outage also provided an opportunity to do ancillary repairs across adjacent crossovers, roof panels and stair tread repairs. Staff said in-house tradespeople and track crews performed most of the work and that the agency will order the remaining castings for a similar outage next year to restore another 15 years of service life.

Board members praised the execution and asked staff to document lessons learned and share them with peer agencies. Staff said about 150 staff and contractors supported the weekend effort and that the work was planned a year in advance to secure the castings and coordinate schedules.

What’s next: staff will proceed with the second casting replacement next year and provide a lessons-learned briefing to the board if requested.