The progressive design-build Atlanta Plane Train Tunnel West Extension Project at Hartsfield-Jackson Atlanta International Airport includes extension of the existing automated people mover system and terminal renovations at the baggage claim station. The project adds a switch and tail track west of the current western end of the Plane Train system to enable reduced headways and to increase capacity, accommodating future ridership.
Delve Underground is the lead designer for the Clark/Atkinson/Technique design-build joint venture. We are responsible for managing the design and performing the following: tunnel and structural design (both temporary and permanent): underpinning design for the terminal structure; geotechnical engineering; design of secant pile shaft and cast-in-place culverts; settlement estimates and structure impact classification; building protection and instrumentation plans; and development and implementation of a real-time instrumentation and monitoring program to provide data necessary to adjust sequential excavation method procedures to prevent impacts to adjacent structures and utilities. In addition, Delve Underground is managing subconsultants responsible for alignment; terminal design; vertical circulation; wayfinding; fire life safety and tunnel ventilation; civil, mechanical, and electrical; and surveying.
The progressive design-build approach for this project includes predesign, design, and construction phases, which provided the team with flexibility to develop and consider alternative design and construction approaches during the predesign and design phases of the work. This resulted in several improvements to the project including the elimination of an unnecessary shaft, resequencing surface improvements above the construction shaft, replacing ground improvement by grouting with underpinning of the shallow terminal foundations in the mixed face area below the existing terminal, and changing the vertical circulation approach to a fully end-loaded concept.