Special features of scheduling tunnel works - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 278

Invert heading: average 300 m/month.
Enlargement: average 235 to 240 m/month.
The tunnel was actually completed 16 months ahead of the officially agreed deadline.
Figure 7-1 Diagram of the working method for excavation and timbering (support) in the Hauenstein
Base Tunnel [257].
Fig. 7-2 shows a typical work progress plan with the planned and actually achieved dead-
lines.
Construction progress. At a time when tunnels were excavated by laborious manual
labour with hammer and pick, or at best with relatively ineffective low-explosive gun-
powder, the process of “breaking” had such overriding importance that other works were
relatively insignificant. It was only possible to influence the advance rate by employing a
larger number of hewers working at the face, which was of course restricted by the avail-
able space.
If we compare the monthly advance rates achieved in two classic tunnels of that time, the
Mont Cenis and St. Gotthard Tunnels, then the considerably faster progress in the St. Got-
thard Tunnel can be recognised:
1. Mont Cenis Tunnel, v = 168.7 m/month (working from both ends in October 1870).
2. St. Gotthard Tunnel, v = 243.8 m/month (working from both ends in October 1875).
It should be remarked that drills were in use in both of these tunnels, although in the
Mont Cenis Tunnel, the use of drills was more in the nature of a trial and that also only
traditional gunpowder was used. In the St. Gotthard, on the other hand, the tunnel site was
better equipped with improved drills and high-explosive (dynamite) being used.