It's part of the tunnel system the power company built to use water coming off the glacier.

Tell him to have detailed plans of the tunnel system ready.

We've learned they might have plans to attack the tunnel system.

So, they had taken his beloved tunnel system away from him.

Above ground movement during the winter months is restricted to these tunnel systems.

For it's important to know if the tunnel system ever brings you back to a place you've been before.

The official also said it appeared that Chicago's tunnel system was unique.

The resulting huge tunnel systems are, in some cases, centuries old.

The tunnel system is used for communications and utility service.

The tunnel system had a total length of 340 meters.