Mechanical ventilation of tunnels is costly because of the initial installation and the continued maintenance and operation. However, at some tunnel length corresponding to a particular altitude, traffic configuration and topography there is a need for this forced ventilation. This study was undertaken to help determine the pollution concentration in existing tunnels in Colorado, and predict the length of tunnels which will need mechanical ventilation....

Describes what tunnels are, how people use them, and how they are made, and provides step-by-step instructions for making five projects related to tunnels.

In this vividly descriptive short study, Peter Ackroyd tunnels down through the geological layers of London, meeting the creatures that dwell in darkness and excavating the lore and mythology beneath the surface. There is a Bronze Age trackway below the Isle of Dogs, Anglo-Saxon graves rest under St. Pauls, and the monastery of Whitefriars lies beneath Fleet Street. To go under London is to penetrate history, and Ackroyd's book is filled with the...

When rain forces the campers to stay indoors, Jo and Molly try tabletop games and Ripley, April, and Mal discover a secret tunnel beneath the kitchens containing a giant, prehistoric bug.

"Highlights the many techniques that earned the Glenwood Canyon highway project the American Society of Civil Engineers' Outstanding Civil Engineering Achievement award for 1993."