Completed in September 1995, the $194.5 million Calumet Tunnel in south suburban Chicago represents public-works construction at its best. The project set five world records for tunneling: best hour (14.9 feet), best shift (96 feet), best day (242 feet), best five-day week (1,064 feet), and best month (3,993 feet).
With work proceeding around the clock, it became clear early in the project that an aggressive concrete-lining operation would be needed to take advantage of the record-setting tunneling rates. Using an on-site batch plant, a 30-foot-diameter telescopic form, and shuttle trains to transport the concrete to the pump, crews lined the 11.6 miles of tunnel in 395 cycles, averaging more than 155 feet per day. The 4000-psi, air-entrained concrete mix was produced by a 180-cubic-yard-per-hour central-mix batch plant.