TUNNELS.

Progress, Volume II, Issue 6, 1 April 1907, Page 210

TUNNELS.

The past year has been remarkable for the activity which has been shown in the construction of tunnels and subways. It would seem indeed as though we were witnessing the close of the era of bridges, and the opening of an era of tunnels ; for the tunnel is taking the place of the bridge and viaduct, both for the crossing of waterways and in the provision of means of rapid transit in cities and thickly populated districts. A record in speed of construction was recently made in one of the tubes of the Hudson Company's tunnels where a shield was advanced 72 feet in a single day. The large amount of valuable experience gained by our engineers has resulted in the use of improved methods and better machines. As evidence of this it may be mentioned that the Hudson River tubes are now being driven through the mud by the displacement method, the material being thrust aside by the advancing shield, instead of being taken in through the door of the shield.