5.3 km-long connection under construction by Selmer for Statens Vegvesen between the islands of Hitra and Froya located west of Trondheim to complete all-weather link to mainland. Development of 55 m2 two-lane single tube from both portals using two Atlas Copco 353S-1838 drillrigs equipped with Bever Control which handle all face, probehole and rockbolt holes. Maximum advance in each heading 110 m/week in predominantly gneissic rocks with a few bands of limestone/marble. 3.6 km subsea at maximum depth 150 m. 8,000 cement-grouted rebar spiles installed over the crown in umbrellas with 2-3 m overlap in poor ground which comprises 3 % of alignment. 10,000 m2 shotcrete and 250 linear m of concrete lining expected, together with 200 linear m of floor concrete. 120,000 m of probeholes drilled to date. Work commenced February, 1998 from Froya portal using slurry explosives under wet conditions and March, 1998 from Hitra using Anfo under dryer conditions. There is an overall cost balance between the two types of explosive: slurry is more expensive but less noxious so requires less ventilation and offers faster re-entry. There is no detectable difference in their relative blasting efficiencies. May 1999.