General | 14. April 2021 MM1018 – Highway Blitz of Sign Gantries

At the end of 2020 we were again commissioned with a refurbishment of sign gantries. This time, the gantries were located in the metro area of Bremen.

Previously, gaps and tolerances were noticed during approval tests for handing over the traffic sign bridges to the building owner. After a detailed inspection of the head plate joints, it was found that the transom-stem connections on three traffic sign bridges did not comply with the ZTV-ING (2012 version). This prescribes the following transom-stem connection in Part 9 Section 1 under 5.4 (3):

“The ledger-stem connection shall be designed so that the ledger rests on the full surface. A connection can be assumed if a gap of 1 mm is not exceeded at any point and the gap over at least 2/3 of the base area is less than 0.5 mm.”

This gap compensation had to be carried out quickly, efficiently and in accordance with the current rules of technology as specified by ZTV-ING. Among other things, a 100 % support had to be created and a friction-locked connection had to be produced. In addition, fatigue strength was an important requirement.

We took over and handled the entire job logistics and applied for and subcontracted the highway closure ourselves. One of the biggest challenge  here was to disrupt the flow of traffic as little as possible. By means of a mobile barrier, all three locations that had to be worked on could be reached on the same day. In that fashion, only one lane of traffic was closed in each case for less than an hour.

On the first day, the injection connections for the actual gap balancing were placed and the gap was sealed with our MM1018 Seal #2108, which also provides a 100% force fit.

On the second day, we started filling the void by injecting our MM1018 FL material, also known by its synonym liquid shim, and completed it successfully.

Our MM1018 FL has a compressive strength of 161 N/mm², making it ideally suited to withstand the loads. The compressive swell tests to determine the fatigue strength of gap levelling material was done in cooperation with the Institute for Building Materials Research (ibac) of RWTH Aachen University. It did show that our material was the most suitable.

Thus, we were again able to ensure a 100% form and force-locking gap compensation by using our MM1018 FL and our proven injection procedure, carried out by our trained personnel.