The new Direct Air Rail Transit runs from the existing Network Rail Luton mainline station to the new Central Terminal underground station which is adjacent to the Airport South Apron area. Part of the line will run underground and we were appointed by the D&B contractor JV to undertake an independent Category 3 check of the twin light rail system cut and cover tunnels.  The tunnel is a reinforced concrete twin box constructed in sections within a propped temporary sheet pile cofferdam.  The cofferdams were constructed in a sequence dictated by passing below the existing airport taxiway and immediately adjacent to the existing Airport Approach Road.  The independent detailed check involved a review of the available ground information to determine a ground model and design soil parameters for use in the analysis.