Risk Management of a Light Rail Mega-Project in Seattle: A Case Study

The Central Puget Sound Regional Transit Authority, better known as Sound Transit, completed the Northgate Link Extension (NLE) light rail project in 2021, on schedule and under the approved budget. The NLE project is a 4.3-mi light rail project in Seattle, Washington. The project extends the Link light rail system north from the existing University of Washington Station to the Northgate neighborhood. A majority of the alignment is underground, and it includes two new underground stations (U District and Roosevelt) and one elevated station (Northgate). Construction of the underground tunnels utilized two 21.5-foot diameter tunnel boring machines (TBMs). The total project budget was $1.9 billion. The NLE project used a risk and contingency management plan (RCMP) to define the processes and procedures to conduct risk assessments, manage risks, and manage contingency throughout the project life cycle. As the project also relied upon federal funding, the RCMP aligned with the Federal Transit Administration’s (FTA) Oversight Procedure for Risk and Contingency Review (OP40c). Together, these procedures required NLE to apply quantitative risk assessments (QRA) at major project milestones. The purpose of this paper is to present the applied risk management processes, discuss how the QRA results evolved at major milestones, how the nature of risks changed over time, and offer recommendations for future risk management processes for mega-projects.