Twin Box Tunnels - Liberty University, Lynchburg, Virginia

Welcome To Brierley Associates You Tube Site! You may learn more about Brierley Associates and how we "Create Space Underground" by visiting our website www.brierleyassociates.com The video you will be viewing is a time-lapse of the South Tunnel Installation at Liberty University,Lynchburg,Virginia. This project, designed and managed by Brierley Associates, and constructed by Southland Contracting, is located on the campus of Liberty University on Regents Parkway north of the intersection with Williams Stadium road on the west side of the campus. The entire project consists of two side by side 2,100 ton,16 foot high, 28 foot wide, 130 foot long cast on-site reinforced concrete box tunnels. Once completed, the tunnels will convey four lanes of vehicular traffic beneath active rail lines operated by Norfolk Southern. The tunnels will provide access to Liberty University from Ward Road at the intersection with Harvard Street and will benefit the University as expansion of campus facilities is underway Although conventional construction of these types of tunnels is by jacking, a novel approach was selected to pull the first box through the existing railroad embankment via post-tensioning tendons installed through the embankment and walls of the tunnels. The six 840 ton capacity jacks were mounted on four foot thick reinforced concrete blocks, cast against a 23 foot high soldier pile reaction wall located at the receiving side of the embankment. The tunnel was jacked to within 35 foot of the reaction wall and was day-lighted during demolition of the reaction wall. Elements of this project include installation of temporary excavation support systems to construct the launching and receiving areas; geotechnical instrumentation to monitor ground deformations; control of ground loss at the heading and deformation mitigation of the railways via spiles placed using trenchless technology; installation of conduits through the embankment to protect post-tensioning tendons; construction of a reinforced concrete launching pad and four reaction blocks at the receiving area. Work to launch and jack the second (north) box tunnel began on January 6, 2014 and the drive of the 130 ft long box was successfully completed during the early evening hours of Thursday, January 9, 2014. Brierley's Project Manager and Resident Engineer, Jeremiah Jezerski and Brierley's President AJ McGinn both extend their congratulations to Clay Griffith of Southland Contracting for a job well done and managing the challenges of this project.