Special features of scheduling tunnel works - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 277

7 Special features of scheduling tunnel works

7.1 General

The scheduling of tunnelling works has a few special features, which are discussed in this
chapter together with the general procedure.

7.2 Historical overview

General. Detailed reports of the planning of operations and working sequence for com-
pleted tunnel projects have been available for more than 200 years. The names F. Foetterle,
R. v. Gunesch, A. Lorenz and F. Ržiha make it clear that it were tunnel engineers, who had
already recognised the importance of tight planning of the construction schedule [131] .
This early recognition of the necessity of scheduling in tunnelling was not simply a co-
incidence. Increasing industrialisation in the 19 th century demanded rapid development
of transport, which could not be delayed by interminable waiting for the completion of
tunnels. The limitations of working space (each group of workers created the working
conditions for the following group of workers) did not permit faster working simply by
employing more men. Construction periods of up to 20 years were no exception. The basic
methods for quicker working were only invented in 1861 with the hammer drills used in
the Mont Cenis Tunnel (Fréjus Rail Tunnel) and the invention of dynamite in 1867 . This
period also saw the introduction of the time-distance diagram, also called time-chainage
diagram, which were then more accurately called work progress plans. Such plans also
served as progress plans for invoicing and documentation for the employer, and also as
insurance in the event of any legal disputes; scheduling overruns were subject to very
high contract penalties at the time. The contractors had to accept most of the risk from
geological conditions, with the effect on construction time and overbreak. Quite a few
well-known tunnelling contractors became the victims of an unreasonable distribution of
risk [131].

Examples for the planning of tunnelling works are given by the former Lupkower Tun-
nel in the Carpathian mountains, which was built by R. v. Gunesch in the then extremely
short time of 2 ½ years [131], and the building of the 8,134 m Hauenstein Base Tunnel
between 1912 and 1915 (Figs. 7.1 and 7.2). This was the first large mountain tunnel where
the invert heading was drilled with compressed air hammer drills leading to improved and
above all more uniform progress. In detail, the following advance rates were achieved: