a
c
d
b
e
Tunnel_003
a
Centreline or axis
b
Rotation point
c
Centreline offset
d
Centreline height offset
e
Superelevation (Rotation)
43.6.14
Tunnel - Elements for Stake and Check Measurements
Staking tunnel faces
It is usually required to stake out the tunnel face to indicate the position to
excavate when certain tunnelling methods are used. For example, Drill and
Blast or excavation using a roadheader.
The points to stake on the tunnel face can be defined in various ways:
Horizontal and vertical offsets
By horizontal and vertical offsets with respect to the centreline:
d
c
b
a
Tunnel_004
a
Centreline
b
Point on tunnel face to stake
c
Centreline offset
d
Centreline height offset
Distance along profile
By the distance from the start of the design profile and an offset from the
design profile.
d
e
c
b
a
Tunnel_005
a
Centreline
b
Point on tunnel face to stake
c
Point defining start of design
profile
d
Distance from start of design
profile
e
Offset perpendicular to design
profile
Superelevation
Tunnel face
700
Roads - General