Managing geotechnical risk on US design-build transport projects

Kevin Mclain,Douglas D Gransberg,Micheal C Loulakis

doi:10.5130/ajceb.v14i1.3745

Abstract

Awarding design-build (DB) contracts before a complete subsurface investigation is completed, makes mitigating the risk of differing site conditions difficult, if not impossible. The purpose of the study was to identify effective practices for managing geotechnical risk in DB projects, and it reports the results of a survey that included responses from 42 of 50 US state departments of transportation and a content analysis of DB requests for proposals from 26 states to gauge the client’s perspective, as well as 11 structured interviews with DB contractors to obtain the perspective from the other side of the DB contract. A suite of DB geotechnical risk manage tools is presented based on the results of the analysis. Effective practices were found in three areas: enhancing communications on geotechnical issues before final proposals are submitted; the use of project-specific differing site conditions clauses; and expediting geotechnical design reviews after award. The major finding is that contract verbiage alone is not sufficient to transfer the risk of changed site conditions. The agency must actively communicate all the geotechnical information on hand at the time of the DB procurement and develop a contract strategy that reduces/retires the risk of geotechnical uncertainty as expeditiously as possible after award.

Highlights

The current emphasis on accelerated project delivery in the US creates an environment where public engineers may be forced to focus on expediting the procurement process rather than fully developing the project’s geotechnical requirements
The 2006 Report to Congress found that less than 3 per cent of total highway projects were delivered using DB (Federal, 2006) and, because DB transport projects could only be delivered after obtaining Federal Highway Administration (FHWA) permission via the SEP-14 application process, the overall impact of managing geotechnical risk has been low on a nation-wide, programmatic basis
Ho et al go on to advocate the use of quantitative risk assessment in conjunction with traditional deterministic methods to better communicate geotechnical risk throughout the project’s design and construction process

Summary

Introduction

The current emphasis on accelerated project delivery in the US creates an environment where public engineers may be forced to focus on expediting the procurement process rather than fully developing the project’s geotechnical requirements This includes evaluating how much of the geotechnical investigation should be done by the design-builder after contract award. A critical discourse on the subject of quantifying geotechnical risk in the design asserted that “designers sometimes wishfully classify those factors which they cannot confidently characterize as being of minor importance, or hope that such imponderables would be compensated by conservatism built in the system elsewhere” (Ho et al, 2000) This notion agrees Baecher’s findings regarding the weakness of using fixed factors of safety. Van Straveren (2000) builds on the quantitative risk analysis theme and extends the argument to actively managing geotechnical risk across a project’s entire life cycle with a focus on articulating risk during procurement and cited a “1:10 cost-benefit ratio...as a result of better contracting practices by improved risk allocation.”

Objectives

Methods

Findings

Conclusion