Rehabilitation of LaSalle Drive Bridge Deck
Firm: Stanley Consultants
Other Consultants: CivilTech Engineering, Inc., Acura, Inc., Apex Consulting Engineers LLC, Lakeshore Engineering, LLC
Owner:Chicago Department of Transportation
Description:THE PROBLEM: Chicago’s deteriorating LaSalle Drive Bridge Deck needed to be replaced. Construction on the heavily traveled roadway would cause further congestion.
THE SOLUTION: The initial solution was to repair the deck in 60 calendar days by removing the existing concrete latex overlay and installing a new concrete latex overlay.
However, after the project was let, Chicago officials made the decision to reduce the schedule from 60 calendar days to 40 calendar days so that construction did not begin until after the Chicago Triathlon and had to be completed prior to the start of the Chicago Marathon. Both of the popular lakeshore events would increase delays on the congested Lake Shore Drive and construction would further impede travel.
The deck removal process was changed from hydro-scarification to the more traditional process of grinding off the surface with a milling machine. The schedule reduction led to a change from latex concrete to stone matrix asphalt (SMA) surface. The move to asphalt made it possible to implement an experimental feature on the project using longitudinal joint sealer as a waterproofing membrane on the deck, a first of its kind in Chicago. The implications are greatly reduced materials and labor costs during installation.
The 33 percent reduction in the project schedule, combined with the discovery of the dual deck, required innovative time saving measures to complete the project within the condensed schedule.
Stanley Consultants recommended staging plan improvements by combining the planned six stages into two stages and eliminating additional concrete deck curing periods and downtime due to relocation of traffic control and scaffolding. This required scaffolding span the entire underside of the deck instead of relocating it for each of the six stages per plan. Stanley Consultants also worked with the contractor to develop a plan to work double shifts to meet the new deadline. Each of these recommendations were implemented to complete all work within the new timeline.
The inconvenience to the traveling public was minimized during construction as much as possible. While the compressed timeline did add cost to the project’s construction value, Stanley Consultants was able to work multiple shifts and deliver the project spending less than its negotiated contract value.
The project was successfully completed within the reduced time frame and the Chicago Department of Transportation is pleased with the results.
Chicago Department of Transportation