When the Virginia Department of Transportation (VDOT) launched an effort to rehabilitate 20 bridges along I-95 in the Richmond area, it faced a monumental challenge. Recent bridge inspections had classified all of the bridges as either “functionally obsolete” or “structurally deficient,” which meant crews would need to perform substantial repairs and replacements.
At the same time, the highway is one of the most heavily traveled interstate corridors in the country, serving as a key artery for East Coast travelers and a major thoroughfare for Richmond-area commuters. Shutting down the roadway to the 160,000 vehicles that travel through the area each day was not a viable option.
VDOT chose Michael Baker International, a leading provider of engineering, planning, and consulting services, as the construction engineering inspection team for the $106.7 million, multi-year initiative. Michael Baker’s integrated approach to the complex project included a mix of Accelerated Bridge Construction (ABC) techniques and careful coordination of a variety of stakeholders. In the end, Michael Baker’s inspection oversight to VDOT’s ABC solution meant fewer traffic restrictions, a safer ride for motorists during construction, and a dramatically improved roadway once it was completed — all at a lower cost than Virginia had initially anticipated and delivered months ahead of schedule.
Accelerating the timeline
The number of major road projects in Virginia has been increasing over the years, and most active work zones are located on existing roads. The projects can generate traffic disruptions in heavily urbanized areas. They can also create safety hazards for motorists and workers and can negatively impact local businesses. Because of this, the Federal Highway Administration has established several programs to enhance work zone mobility and safety and to shorten project construction time.
In the early stages of the I-95 bridge rehabilitation project, both VDOT and Michael Baker determined that maintaining traffic flow and keeping both construction workers and the traveling public safe were paramount.
To this end, the team decided that the most efficient way to perform the bridge superstructure replacements was to use ABC delivery techniques that combine innovative planning, design, materials, and construction methods in a safe and cost-effective manner to reduce onsite impacts and save time. ABC technology has been refined during the last several years to deliver fast bridge replacements by prefabricating various elements offsite and then erecting or moving them into the final bridge location.
VDOT chose to prefabricate complete modular concrete deck slab and girder superstructure elements offsite in a casting yard, deliver them with specialized multi-axle transport trailers to the bridge locations, and erect them after demolition and removal of the existing bridge superstructures. Crews then tied the modular units together with either post-tensioning bar tendons or cast-in-place, high-early strength concrete closure pours.
The use of new ABC technology for construction and installation of prefabricated bridge elements and systems greatly reduced onsite construction time compared with the use of conventional construction methods. Workers built the elements of the bridges under controlled environmental conditions, eliminating the influence of the weather. This contributed to a better-quality product and longer durability for the spans.
Bridge restorations required multiple lane and ramp closures. Therefore, complex construction phasing, maintenance and protection of traffic, work zone safety, stakeholder coordination, and public outreach were critical project elements, especially because crews performed most of the work at night and on weekends.
Michael Baker’s comprehensive construction engineering and inspection program included precise scrutiny of the preparation of pre-constructed composite units (PCUs) at the offsite casting yard; oversight of an innovative and malleable maintenance of traffic scheme; a project-specific, custom-designed SharePoint-based document management system; and proactive public involvement.
Checking the backyard
The casting yard was a critical path to achieving precise scrutiny of the preparation and quality of the PCUs. The contractor needed a site that was large enough to accommodate all of the activities associated with producing and storing 234 PCUs. The yard also needed to be in close proximity to the bridge locations to ensure that the 120-ton units could be hauled across existing structures on the way to their final destination.
The contractor chose a 25-acre site approximately three miles from the project area. The yard consisted of two large concrete casting beds in which the contractor recreated the exact geometric layout of the existing substructure. This critical element helped ensure that the PCUs constructed at the casting yard fit precisely together at the site. Under Michael Baker’s supervision, all PCUs were match-cast transversely to ensure that the post-tensioning bar ducts lined up and the PCUs fit perfectly together in the field.
Constant coordination and communication
The use of advanced ABC techniques required constant communication among the project team, the traveling public, and the business community. Michael Baker’s services included assistance with the interpretation of contract documents, oversight of the construction of precast units, review and documentation of materials certifications, review of the materials testing and quality control process, facilitation of construction meetings, and review of the contractor’s payrolls and monthly utilization reports. Michael Baker also reviewed and helped coordinate all traffic detours and closures, performed work zone safety checks, monitored environmental compliance, and evaluated the contractor’s performance.
Because of the sheer volume of paperwork connected to the project, Michael Baker developed and maintained a customized SharePoint-based document control system used by inspectors to prepare daily work reports (DWR). With this system in place, inspectors automatically issued DWRs to managers via email for review and approval. This greatly increased the overall efficiency of an already compressed schedule.
The VDOT/Michael Baker team also was able to successfully and efficiently manage the many shop drawings, submittals, permits, and requests for information using the SharePoint document system. Stakeholders submitted, reviewed, and approved more than 4,000 individual documents, resulting in substantial time and cost savings.
Staying in the lane
To complete repairs to the 20 bridges on I-95, the VDOT/Michael Baker team managed an extensive maintenance of traffic plan that reduced three lanes of traffic to one lane in both directions while keeping an emergency lane clear. The plan included night-time construction hours, the use of crossovers, and a moveable barrier system or “zipper barrier,” which could be deployed in less than one hour. This was a critical daily activity given the contractor’s limited 10-hour window to replace the superstructure PCUs. Michael Baker coordinated all traffic detours and closures with VDOT’s Traffic Operations Center, performed work zone safety checks, and strictly monitored environmental compliance.
State officials sought to provide advance warning to the traveling public concerning the more than 1,200 individual daytime and night-time lane closures during construction. The VDOT/Michael Baker team maintained constant communication with the City of Richmond and vendors so they knew how construction might affect people’s commutes to and from events, including minor league baseball games, NASCAR races, high school graduations, and other community activities.
The team also utilized other channels to keep the public informed of lane closures and potential delays. These included a project-specific web page, social media outlets such as Facebook and Twitter, the use of a recorded hotline for updates, billboards and overhead message signs, and engagement with the local media.
A project of this magnitude often presents unforeseen challenges. In each instance, VDOT and Michael Baker collaborated to overcome obstacles and keep the project on track and on schedule.
In one instance, construction was performed over CSX Railroad lines, which required a CSX flagger to monitor the tracks. The contractor performed substructure repair, drilled shaft installation, and column and pier cap reconstruction and PCU replacement near the railroad limits. By generating a customized report to isolate DWRs for the CSX right-of-way work, Michael Baker was able to document the flagger hours in conjunction with the construction activities and verify any overruns for flagger costs to the benefit of the client.
Another challenge involved construction over a small creek overpass that did not allow for the use of cranes. Michael Baker worked with VDOT and the construction team to plan and manage an innovative arrangement of utilizing four trolleys with hoists suspended from the girders of the overpass to lift demolition bridge sections and new replacement bridge spans.
Through careful planning, collaboration, and the use of smart technology, VDOT and Michael Baker International created a safer commute for motorists along the heavily traveled Richmond corridor of I-95. The combined team delivered the final product four months ahead of schedule and $16 million below the original budget for repairs, resulting in a cost-efficient, comprehensive solution for the State of Virginia and the tens of thousands of people who travel the roadway every day.
Jorge M. Suarez, P.E., is vice president/director of structural engineering with Michael Baker International (mbakerintl.com). He has more than 35 years of experience in the design and construction of numerous steel and specialized prestressed concrete structures, including concrete segmental bridges, cable stayed bridges, arch bridges, Accelerated Bridge Construction, and bridge rehabilitations.