The 100-plus-year-old Long Island Rail Road Atlantic Avenue Viaduct carries two tracks and more than 25,000 passengers daily. Photo: HNTB
Transit agencies face increasing urgency to update existing facilities and build new ones. Some are operating with increased staffing pressure compared to a few years ago, a reality not expected to diminish soon. Foundational operating structures in some agencies may dictate the way projects originate, get funded, and are completed.
Design-build minimizes risk, reduces delivery time, keeps budgets in line, and mitigates funding partner concerns throughout project duration. With traditional design-bid-build, owners, designers, and contractors are segregated from design concept to final construction. In the design-build environment, the three work as an integrated team from the beginning. It is a proven strategy that helps clients achieve project success and owner satisfaction.
Design-build greatly reduces the resources needed to complete projects. It fast tracks starting, building, and completing jobs. It is essentially, a one-stop shop. Generally, in a two-step procurement process, an owner will release a 30% complete set of design documents to qualified design-build teams as the first step. The contractor then partners with a designer to advance the design to a point where the contractor can determine project costs. Then, the contractor and the designer collaborate to develop alternate technical concepts (ATCs) to reduce costs, resources, and schedules. During the second step, each design-build team’s submitted proposals are assessed. The owner develops a scoring system that accounts for costs and schedule. Points are then allocated for which team brings the most benefit. Each team must demonstrate how it can execute the project, innovations included, and what ATCs can be delivered. Organizational structure and the quality of the design-build team are also considered. Once the owner selects the successful design-build team, the designer then advances the 30% design to a 100% design during the construction phase.
The owner of the Long Island Rail Road Atlantic Avenue Viaduct, the New York Metropolitan Transit Authority (MTA), engaged design-build to meet project goals. The 100-plus-year-old bridge carries two tracks and more than 25,000 passengers daily.
- Replacing 189 spans.
- Designing and replacing longitudinal girder and cap beams.
- Painting the entire structure.
- Repairing columns.
- Installing improved lighting under the viaduct.
The phased project replaced the viaduct’s superstructure, the track, and all utilities while trains continued to operate. Phases 1 and 2 were completed ahead of schedule.
This project is indicative of the design-build growth taking place, especially in the northeastern region of the U.S. Expansion will continue as more transit professionals understand design-build benefits. As more design-build projects reach completion, proof of its viability grows. Plus, workshops to help officials understand the design-build process are ongoing. As more agencies are permitted to use design-build, their teams will be informed about the process and ready to move ahead.
Design-build reduces delivery time, which was evident in the rehabilitation of Amtrak’s Chicago Union Station Yard. Photo: HNTB
The Bay Area Rapid Transit (BART) Warm Springs extension in Fremont, Calif., is another example. The new transit bridge straddles the Hayward Fault, is built to survive displacement from a 7.25 magnitude earthquake, and allow trains to resume operation within a reasonable time.
The 5.4-mile design-build project extends BART’s rail line from Fremont Station to a new Warm Springs Station. The project’s Walnut Avenue Bridge straddles the fault.
Computer modeling software analyzed the effects different seismic events would have on a bridge in the fault zone. Collaboration among BART, the University of California, the contractor and designer created a cutting-edge design: a post-tension, concrete through-girder railroad bridge support on short, seat-type spread footing abutments on top of mechanically stabilized earth (MSE) walls. The MSE wall supporting the southern abutment rests on a load transfer slab, protecting the MSE walls and abutment from extreme differential ground movements.
One important design-build best practice is to know and understand project owners. Building relationships with owners’ staff at all levels helps them understand what is critical in the process. It goes without saying, “know the owner, know the owner, know the owner.” This deep understanding lets them develop RFPs that ensure they work with contractors who will deliver the job.
When good relationships are built with owners, a design-build team can help responding contractors better understand the intent, or spirit of RFPs. Contractors are critical to successful design-build projects and must be engaged early. Owners need to be assured their contractors are familiar with the nuances of each job. For example, if an owner needs a rail work, its contractor should thoroughly understand rail systems, rail security concerns, platform construction, track construction, working near active rail lines, working with the railroads force account staff, and related components.
With design-build, contractors can deliver ATCs that improve design and reduce the time allocated on the schedule. For example, if an owner anticipates a schedule should be 36 months long, it can be left open for the design-build team to enhance. It generally gets reduced; often four to six months.
This expediency was evident in the rehabilitation of Amtrak’s Chicago Union Station Yard. The original design was completed in six weeks and operations continued during significant construction of 18 months.
- Seven miles of yard and main track renewal.
- Interlocking construction.
- Rehabilitation of five rail facilities.
- Trackside utilities.
- Bridge work.
Agencies such as MTA are embracing design-build and have hired procurement specialists who are updating the agency’s design-build procurement and RFP processes. Oversight consultants who manage the design-build processes are also being added.
Design-build connects designers trained in the latest technology with seasoned pros, blending a variety of expertise. This process fosters teamwork among owners, designers, and contractors.
Technology such as three-, four- and five-dimensional CAD and building information management technology, or BIM, allows for limitless design variations. Photo: HNTB
Today, technology such as three-, four-, and five-dimensional CAD and building information management technology, or BIM, allows for limitless design variations. For example, a design can be created that ties cost and schedule into it. Changes can be made, including eliminating foundations or making bigger ones and the technology includes pricing data to show both versions. This allows the design-build team to evaluate the best options in terms of cost savings and time savings.
Contractors can now bring designers new ideas and concepts. These newer designers create designs alongside more experienced team members to give owners the best combination of expertise and technology. The whole design-build gets so accurately designed that, when it comes to the bidding stage, designers can literally manipulate thousands and millions of dollars of design considerations.
Owners now prefer designs formatted in CAD with schedules and budgets incorporated. Many of them are incorporating LEED technology into their procurement process. Owners want to make their buildings, their stations, and their systems more environmentally friendly. BIM and design-build help them do this.
Design-build will carry transit projects into the future. Mega projects must go design-build to meet long-term needs. Train speeds must increase and construction to straighten and realign tracks needs flexibility. Design-build lets owners transfer some of their risks to contractors who know how to better manage them using alternate design concepts and experience.
With design-build, we are quickly moving into an integrated and collaborative forum. Owners must support this. Educators need to incorporate design-build into their curriculum so better-informed graduates enter the marketplace. Graduate students must not only focus on design principals, but curriculum should include design-build procurement and how to assess and measure risk and their legal implications. As designers, we must embrace new technologies, be involved in our professional institutions and participate in more online discussion. The more we learn from others in this growing market, the better informed we become.