Safety and safety planning - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 331

- Conventional shotcrete tunnelling produces dust from rock cutting and from dry shot-
crete spraying. Measures are to be described to ensure compliance with the new dust
thresholds according to TRGS 900.
- In order to maintain the thresholds mentioned above, it may be necessary to provide ex-
traction ventilation. The contractor should plan filter systems in order to avoid dust nui-
sance in inner-city areas. This also applies to silos (bentonite, shotcrete, cement silos).
- Diesel-powered vehicles produce diesel emissions. In addition to the ventilation and
extraction concept, the contractor is to demonstrate how monitoring and evidence of
the pollutant emissions from the vehicles in use can ensure compliance with the permis-
sible occupational exposure limits (TRK) according to TRGS 554 of 0.3 mg/m 3 . The
measures intended to prevent this threshold being reached are to be explained.
- When shotcrete is used, the production process is to be selected with regard to health
protection and compliance with dust thresholds, independent of the ventilation and
extraction concept. Only alkali-free shotcrete is to be used. If dry-mix spraying is in-
tended, the mix is to be wetted to reduce dust development. Appropriate eye protection
is compulsory.
- When welding work is undertaken - above all in underground works - ventilation and
extraction are to be carefully planned. In particular, the BGV C 20 is to be complied
with.
Compressed air. For compressed air working (shield tunnelling, pipe jacking), reference
is made to the regulations for working in compressed air in the version of 19 June 1997.
RAB 25 (Rules for health protection on construction sites) is also applicable.
In order to treat patients, who are injured in the pressurised area, a pressure chamber is to
be provided. This applies to all areas where compressed air working takes place. A suitable
lifting device is to be provided to recover this pressure chamber.
In tunnelling, a compressed air cabin is to be provided in the shield machine when com-
pressed air is used. The fire services are to be notified about compressed air working
(include in alarm plan).
Noise and vibration
The following are to be described for underground and for overground working:
- Measures to prevent health impairment due to noise and vibration.
The valid regulations are to be complied with, particularly:
- BGV B3 administrative regulation for protection against construction noise, 19 August
1970
- Decree of the German ministry for environment and nature conservation, 31 July 2000
- Measurement, evaluation and reduction of vibration emissions”
Contaminated ground. It is possible that contaminated ground is encountered during
excavation works.
In this case, the following should be noted:
- Work in this case is to be interrupted immediately and measures undertaken to reduce
damage. The site management of the client is to be informed immediately.