RELINING TIMBER-LINED TUNNELS WITH MASONRY 



removed. Tlie remaining space was now clear for completion 

 of the arch, and both sides were brought up until there was 

 not sufficient space for four masons to work, when the keying 

 was completed by two masons beginning at the completed and 

 working back toward the toothed end. The brickwork was 

 built from the top of a staging-car. 



In a few instances where slides occurred after the removal 

 of the slide timbering, the method of retimbering the tunnel 

 shown in Fig. 144 was adopted. Two side drifts were first 

 run 2J ft wide by 4 ft high, and the plate timbers placed in 

 position and blocked. Cross drifts were then run, and the roof 

 segments placed, and the core down to the level of the bottoms 

 of the side drifts taken 

 out The lower wall 

 plates were then placed 

 and the hip segments 

 inserted. The bench 

 was then taken down 

 by degrees, the side 

 plates being held by 

 jacks, and the posts 

 placed one at a time. 

 As the masonry at the 

 points where slides occur consists of 30-in. walls and six-ring 

 arch, the timbering was 22 ft wide in the clear, with other 

 dimensions as shown in Fig. 144. 



Only a single crew of brick and stone masons was employed. 

 In order to prepare the sections for these masons it was 

 necessary to have timber ami trimming crews at work through- 

 out the whole day of 24 hours, so that an engine and two train 

 crews were in constant attendance. Tin- single mason crews 

 were able to complete 8 ft of side wall and art-h in 24 hours. 

 The numl>er of men actually employed at the tunnel was 85. 

 This included electric-li^lit niaintcnaix , and nil other lal>or 

 pertaining to tin- w>rk. The tunnel was lighted by an Edison 



GOM Section. Longitudinal Section. 



Fio. 144. Itellning Timber-Lined Tunnel, 

 Great Northern Ry. 



