1.   The tunnel had to be closed after an explosion caved the roof in.

2.   All Alpine tunnels have their particular risks.

3.   All major tunnels have extensive ventilation, often pushing fresh air up from below and removing engine exhaust from above.

4.   He said the tunnel might have poor drainage, a common problem in older parts of the network.

5.   Investigations found that both tunnels had serious safety problems, including extremely limited escape routes and inadequate exhaust systems to remove large amounts of smoke.

6.   Penttinen said the tunnel has the potential to be fitted with oxygen-regulating equipment that could simulate high-altitude conditions.

7.   The tunnel does have a site, www.atmb.net, and it provides some news of progress on reconstruction.

8.   The tunnel previously had only one entrance.

9.   The tunnels have a capacity of about a million bags, and Daavi said he expected the project to continue long after his death.

10.   Austrian officials said they feared the Tauern tunnel might have to remain closed all summer, causing enormous problems for vacationers.