Subsurface Work Can Benefit From Some Small Changes

By William J. Angelo

	Brierley

While design-build offers many well-known cost and savings advantages on building and heavy civil projects, its use on subsurface projects such as tunnels and deep foundations has been slow to catch on. But that is changing. One way design-builders can help accelerate the process is by adopting lessons learned from a long history of successful design-bid-build projects.

When design-build goes underground, the designer becomes liable for lots of risk not found on a surface project, says Gary Brierley, president of Brierley Associates, Littleton, Colo. "When you win [an underground] design-build job, it’s equivalent to winning a foot race over a cliff. Sometimes you survive, sometimes you don’t."

Design-build can save time and money underground but problems can arise if the designer and constructor differ in their interpretation of the plans and specifications or there are differing site conditions or surprise environmental issues. The lesson that can be learned from successful design-bid-build projects is that there must always be clear communications among the parties and a fair and clear assignment of risk, according to Brierley.

About 95% of Brierley Associates’ work is underground design. The firm averages about $2.5 million in annual revenue and has completed 12 design-build jobs. Brierley believes that risk is increased when the contractor uses one team to develop a proposal and win the project and another team to build it. He says communications between the two teams and the designer easily can break down and cause friction. Frequently, the construction team feels that the proposal team and the designer made too many concessions and promises to the owner, he adds. "After the award, what you typically get is a cost-driven project manager who just wants to get the job done," says Brierley. "That causes tension because the engineer, who is part of a team, has no independent source of authority to get its way or to accomplish significant design requirements and that may impact long-term project performance."

Many important decisions must be made without direct access to the owner. "The best way to get the job done is to get all the correct answers from the owner or to have it make the decisions before the project is awarded," says Brierley. "But with design-build, designers have to go through the contractor who may disagree with their ideas, so where do the designers go if the owner is out of the loop? Take one decision and multiply it by 100 or 300 times over the duration of the project and you could have serious problems."

The designer sometimes becomes the tail trying to wag the dog because it is very difficult for the designer to obtain the authority to force an issue with the contractor. A typical tunnel design might take three months but the contractor wants it in six weeks and the designer ends up doing it in two months. "Is that a one month savings or two weeks delay? It all depends on how hard the contractor wants to be," says Brierley.

To meet cost and schedule constraints, some contractors may cut corners. Above- ground problems can be fixed, below- ground problems can be a disaster. Many underground projects have a service life of 75 to 100 years and are very difficult and expensive to fix if problems arise after completion, says Brierley. "When something goes wrong on a design-build job its very easy to blame the designer," he says. "The owner is insulated from risks and it is easy for the contractor to say he relied on the professional judgement of the designer."

Many owners try to transfer all ground-condition risks to the design-builder and many contractors will hold the designer responsible if something goes wrong. The designer therefore is greatly affected by the prime agreement, says Brierley. Disputes can get expensive because underground work can have a big impact on adjacent property, he adds.

Despite the concerns, there are advantages to adopting some simple design-bid-build lessons. "It all revolves around proper structure and behavior," says Brierley. "The owner still needs to do a thorough subsurface investigation and the contract should include a differing site conditions clause like you would find in a typical design-bid-build contract. That may seem to contradict design-build principals but it ensures reaching the owner’s objective," says Brierley.

Designers also need the kind of authority they have in traditional project delivery, says Brierley. "The owner must ensure that the designer has full authority to implement a safe finished facility....This must be addressed in the prime agreement, like you would find in a D-B-B deal," he says. "It’s OK to be cost effective on temporary facilities and means and methods, but the important design characteristics of the finished facility must be right."

Owners should be made aware of the consequences of passing off critical decisions to the design-build team. But properly done, design-build can offer significant advantages on subsurface work.