Abstract Manager

Major urban rail projects frequently require deep excavations within dense, legacy utility environments, where undocumented assets, limited clearances, and aging infrastructure significantly increase delivery risk. These challenges are often compounded by variable subsurface conditions and the need to maintain critical utilities in service during construction. While utility conflicts are commonly addressed during construction, experience on major urban rail programs demonstrates that many risks are established much earlier through utility design assumptions, investigation strategies, and decision-making. 

This presentation examines utility design management as a formal risk management discipline and its direct influence on constructability and excavation outcomes. Drawing on experience from major urban rail projects involving deep station, this presentation links specific design-phase decisions to construction-phase outcomes. It demonstrates how reframing utility design management as a formal risk discipline can reduce excavation risk and improve constructability. The approach includes early identification of high-risk utility interfaces, constructability-led design reviews, documented utility design assumptions with clear decision ownership, and collaboration among designers, contractors, utility owners, and transit authorities. These design-phase actions were evaluated against construction-stage outcomes related to excavation sequencing, utility protection strategies, and service continuity. 

One example involved a deep regional sewer located beneath proposed twin rail tunnels at a major urban intersection. Although historical as-built records were available, subsurface utility engineering investigations could not confirm the sewer’s precise alignment or depth at the crossing location. Early identification of this risk by the utility design team led to agreement with the asset owner on minimum clearance criteria and the development of a targeted, low-disruption investigation method to establish the sewer depth. Resolving this uncertainty early avoided the risk of late-stage tunnel and station redesign, schedule delays, and significant cost and claims exposure. 

A second example involved deep excavation works in a dense urban corridor where undocumented, century-old watermains were encountered during construction. Discrepancies between available records and actual field conditions resulted in unplanned service interruptions, emergency repairs, and schedule impacts. This example highlights the consequences of unresolved utility uncertainty and reinforces the importance of early investigation, conservative design assumptions, and coordinated stakeholder response. 

This presentation provides practical, experience-based lessons on embedding utility risk thinking early in project development to avoid costly and unsafe excavation-stage consequences. Attendees will gain insight into how early utility design assumptions, decision accountability, and risk traceability translate into safer, more predictable outcomes, and how proactive utility design management can prevent costly, disruptive, and unsafe consequences during construction.