(Above) A construction barge on the Chicago River west of the State Street Bridge on May 2. The area at right, between two lines of steel beams, will soon be filled in to expand the Riverwalk outward. (Click on images to view larger versions.)
12-May-14 H-piles and sheet piles are nice but what will really give the Chicago Riverwalk stability will be its caissons.
Steel cylinders, 75 feet deep, six feet in diameter, and open at each end will be pounded into the riverbed. After the soil is drilled out, rebar will be lowered into each caisson, which will then be filled with concrete. The rebar, used to reinforce the concrete, will be in the form of a steel cage running the full height of the caisson.
A caisson-drilling machine will be delivered to the construction site this week. On Thursday, the Chicago Department of Transportation expects to begin drilling the first caisson on the east side of the Clark Street Bridge.
As concrete is poured into the caisson at Clark Street, the north sidewalk of Wacker Drive will be closed to pedestrians, along with two of the three westbound lanes.
CDOT construction manager Oswaldo Chaves says all of the piles sheet piles that form the river wall and steel H piles that will anchor the Riverwalk to the riverbed will be installed between State Street and LaSalle Street by May 23.
Workers will continue to remove the old concrete this week. They will then fill in the spaces between the existing river wall and new sheet piling, starting with areas west of Dearborn Street.
(Above) Seen from Wacker Drive in front of Marina City, the tour boat Lila passes the construction barge between State and Dearborn Streets. In the foreground are steel sheet piles that will form the new river wall.
River safety committee warns boats to slow down, expect delays
Meanwhile, the Chicago Harbor Safety Committee issued its first warning to boats navigating past the Riverwalk construction. The channel, through which boats maneuver, says the committee, has been dramatically reduced, with barges taking up at least half the width of the river.
Expect long delays, says the committee formed last year to improve safety on the Chicago River and parts of Lake Michigan. This section of the Chicago River should be considered a hazardous construction zone. Boaters should avoid transiting the zone unless necessary. If boaters must transit the zone, please exercise extreme caution.
Advice includes traveling in single file at a safe speed, not overtaking other vessels, and no fishing.