Dewatering, waterproofing and drainage - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 214

acoustic or thermal tests. The aim should not be perfection, but the practice until now, with
these details being dealt with by personnel on site without even plans, cannot be allowed
to continue. Detail drawings with the complete design and specification of all details and
their testing are essential.
5.3.1.6 Maintenance
The following interests of the operator with regard to the maintenance of the tunnel can
have a considerable influence on the waterproofing requirements:
- Possibility of checking for leaks.
- Localisation of the damage when leaks are detected.
- Practicality of leak repair.
- Design for the planned use lifetime.
- Protection of the tunnel equipment against water.
5.3.1.7 Requirements of the users
Accidents in road and rail tunnels can have very serious consequences, as has been shown
recently by the examples of Mont Blanc and St. Gotthard. The safety and comfort of the
users is therefore also of central importance for tunnel waterproofing [82]:
- Prevention of ice formation on the road surface.
- Prevention of icicle formation.
- Prevention of the walls becoming dirty with the resulting darkening of the road condi-
tions.
5.3.1.8 Requirements of environmental and waterways protection
At a time of increased environmental awareness, the requirements to protect the environ-
ment and waterways are ever more important. The requirements of environmental authori-
ties are often decisive for the fundamental design of the drainage and waterproofing con-
cept (pressure-resistant, pressure-regulated or with free drainage). The following points
have to be considered in the design of the waterproofing system:
- Emission of pollutants from the tunnel into the surrounding ground must be avoided.
- Drainage of groundwater has to comply with the conditions of the planning approval.
5.3.1.9 Requirements of cost-effectiveness
The waterproofing can amount to at least 5 to 10 % of the total construction cost of a tun-
nel and has to function correctly to protect 100 % of the structure and the goods within
it. Defects in the waterproofing have a direct and noticeable effect on maintenance costs.
This results in the following cost-effectiveness requirements:
- Minimised construction costs.
- Minimised maintenance costs.