An important point in the repair of manholes is the replacement of corroded or broken climbing rungs (climbing irons, safety steps or ladders) (Abschnitt 1.8).
When installing, the installation instructions must be adhered to. It must be ensured that material, shape and step heights per manhole are the same (see ATV-A 137 [ATVA137]) and that the condition of the manhole wall is such that the exchange is permissible from a statics point of view.
The holes for the new climbing rungs are of necessity to be made immediately above the rungs that have just been removed. For this purpose, a drilling machine has been developed with which the two holes can be drilled at the same time within 2 to 3 minutes.