1a
5
4
4a
Plan
3
1
2
6
Profile
6a
6a
1.
Portal-to-portal tunnel length
1a.
Centerline distance of tunnel
2.
Effective traveled-way width, curb to curb
3.
Horizontal clearance (minimum width of the tunnel bore measured at least 1.2 meters above the
traveled way)
4. Overhead clearance (minimum distance between the top of the traveled way and the lower edge
of the tunnel ceiling or any obstruction below the ceiling such as trolley wires or electric-light wires)
4a. Rise of tunnel arch (radius of curved portion)
5. Radius of curvature of the traveled way (either measured or estimated)
6. Gradient (percentage of rise of the traveled way between portals)
6a. Change in gradient within the tunnel (percentage of rise each way from the break of grade)
Figure 2-9. Tunnel Dimensions
EN 5622
2-18
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