The Houbolt Road Extension was planned to incorporate a new 1,900-foot, eight-span four-lane bridge and approach roadways, providing safer and faster access to I-80. An accelerated schedule was mandated for project completion, leaving only a 40-day window for development of alternative technical concepts and the design advancement necessary for pricing estimates.
Because of the accelerated schedule, a collaborative design-build project delivery model was needed. Following local and state legislative approvals, it became the first transportation project in Illinois authorized to proceed under the design-build method.
This delivery model proved to be ideal to expedite construction, which required advancing permit approvals required from government agencies and other stakeholders. The integrated design-build method allowed several design and construction phases to overlap and expedited permit and construction packaging approvals, with over-the-shoulder reviews and walk-throughs with stakeholders conducted in advance of permitting submittals.
This method paid dividends, given the pressure of the accelerated schedule. The last approval of eight construction packages was received within nine months of the beginning of design.
Thanks to the collaborative nature of the design-build method, a number of design improvements were developed that achieved significant cost savings while speeding up the schedule. These design innovations included elimination of multiple bridge spans, removal of several retaining walls which helped balance earthwork, new cost-saving girder designs and an innovative in-river pier construction method. These features improved overall quality and are expected to extend the life span of the bridge and related infrastructure.
Other design improvements included new stormwater conveyance systems that eliminated unnecessary detention basins, as well as an enclosed drainage system on the bridge. These solutions will reduce impacts to downstream swales maintained by the Illinois Department of Transportation as well as impacts to the Des Plaines River.
The bridge was designed to meet or exceed the Coast Guard standards including horizontal and vertical clearances over navigable waterways, as well as clearance standards specified by the BNSF Railway. The new roads incorporate safety features that include wider outside lanes and shoulders, larger turning radii for trucks, extended acceleration lanes and an adjusted vertical profile to lessen gradients and balance earthwork on both sides of the river.