In Seattle, US, Sound Transit’s Beacon Hill light rail tunnelling and station construction are moving forward with contract completion currently at approximately 52%.

Contractor Obayashi Corporation’s EPB machine, Emerald Mole, reached the Beacon Hill Station this summer after mining 518m of the southbound tunnel and installing 340 segmental lining rings. The geology and ground conditions have been as expected, although the TBM has made faster progress than it was scheduled to.

At the Beacon Hill Station, the contractor is pouring invert concrete for the light rail station’s southbound platform. When this work is completed, the TBM will be moved through the station and re-launched to complete the southbound tunnel drive.

The sequential excavation mining of the 49m deep station is also progressing well T&TI was told. For some activities, the rate of progress has been slower than anticipated, but Sound Transit said there was scope for the contractor and itself to “work together to reduce the amount of schedule float that is used”.

Overall the 25km long Central Link light rail system of which the Beacon Hill works are a part is on schedule for opening in summer 2009. T&TI was told it is on budget and changes to date have been within the contingency allocated.