I-84 and Route 2 Bridge Rehabilitation/Replacement Design-Build

Lochner was the lead designer for this $22.1 million construction project, which was the second design-build project for the Connecticut Department of Transportation (CTDOT) and replaced four superstructures, three located in East Hartford within the I-84/Route 2 interchange and one located in Willington over I-84. The use of accelerated bridge construction (ABC) techniques minimized project costs and helped the design team exceed CTDOT’s project goals. After analyzing multiple options within the alternate technical concept framework, the project team selected three innovative design approaches that brought the greatest value to the project.

For two bridge sites in East Hartford, the project team recommended replacing the bridges entirely instead of only the superstructures. Part of an initiative by Federal Highway Administration (FHWA), geosynthetic reinforced soil, integrated bridge system (GRS-IBS) abutments were used to save on cost and condense the schedule. Lochner’s design included changing the bridge configuration from a three span to a single span, allowing the long lasting and durable GRS-IBS abutments to be constructed quickly and cost-effectively. Rather than setting new superstructures on 50-year-old substructures, Lochner’s approach provided CTDOT with an entirely new structure with a 75-year design life, exceeding their project requirements and reducing costs. Pier columns were removed, and the GRS abutments were situated behind those columns to improve sight distance.

Lochner’s design for the two-span superstructure replacement in Willington included using prefabricated bridge units (PBUs) to meet the accelerated construction schedule. PBUs are a proven construction method that restores traffic on a new bridge faster than conventional methods. This accommodated the two-month detour period during the local school’s summer vacation. Additionally, this method minimized onsite construction activities, improving safety for workers and the public. The PBUs consisted of two steel plate girders with an integral lightweight concrete deck. These units were set in place on the existing substructure during overnight rolling closures of I-84. The lightweight deck minimized the size of the cranes for the picks.

At the Willington site, the superstructure joint over the pier was closed using a simple for dead, continuous for live (SDCL) detail, making the girder design more efficient and less costly while ensuring durability. Lochner’s incorporation of SDCL marked the first time the detail had been used in Connecticut.

While the superstructure replacements were the crux of the project, the maintenance and protection of traffic were also important given the busy I-84/Route 2 interchange, the location to several Connecticut River bridge crossings, and adjacent ongoing construction projects. The plan involved breaking the construction project into four stages at the East Hartford sites, two of which took place in 2018 with the other two following in 2019, to accommodate the schedules of nearby construction projects and to minimize impacts on commuters.

Upgrades were made to highway safety and improved vertical profiles to meet desired design speeds. An existing incident management system (IMS) was temporarily rerouted and then placed within the new superstructure with minimal disruptions to the adjacent camera pole.

Given temporary areas of disturbance of approximately four acres, Lochner developed a stormwater discharge permit registration for this project, which was approved. This proactive coordination was critical for the success of the project and kept it on schedule.

Unlike traditional design-bid-build projects, smaller early release for construction (ERC) packages were developed to allow CTDOT time to review before fabrication began on long-lead items such as structural steel and steel-reinforced elastomeric bearings.