Audit reports

Document Actions

2017 Annual Report - spring report No. 02 "The Federal Government could save €6.7 million in building a tunnel"

To upgrade federal motorway No. A 8 to six lanes, the Ministry is planning to equip the Frasdorf tunnel with shoulders. However, the shoulders are not needed. A smaller special cross section without shoulders would be sufficient to safely accommodate the traffic. The Ministry could save €6.7 million.
Apr 24, 2018

For purposes of noise abatement, the Ministry is planning to build a tunnel with a length of 590 metres. The tunnel is to consist of two tubes with three lanes and one shoulder each. The Ministry justifies the shoulders with the traffic routing during construction: The entire traffic could then be routed in one tube with two running lanes in each direction (4+0 routing). The average traffic load anticipated for 2030 is 65,000 motor vehicles per day. In the Frasdorf tunnel area, the peak loads are expected to total 110,000 motor vehicles per day.

We considered adding the two shoulders to be unnecessary. We recommended that the Ministry build a special cross-section with a carriageway width of 12 metres instead. At times when construction work is underway, the special cross section permits rule-compliant and safe 4+0 traffic routing. Costs could thereby be reduced by at least €6.7 million. In addition to that, we recommended that the Ministry incorporate this special cross section into the nationwide set of regulations.

The Ministry admitted that the special cross section permitted 4+0 traffic routing on building sites. It said it was planning to make the special cross section a nationwide standard for 4+0 traffic routings in tunnels. Nevertheless, the Ministry considers the Frasdorf tunnel a special case and stated that the larger cross section with shoulders was an exception to the rule. The Ministry made reference to the peak traffic load of 110,000 motor vehicles per day during construction. Greater traffic safety could be ensured by having a larger cross section. Furthermore, the Ministry argued that a reduced carriageway width would require changing plans and result in time overruns for approving the planning.

We uphold our opinion that the special cross section is sufficient for the construction of the Frasdorf tunnel. According to the guidance on tunnel construction, a six-lane cross section with shoulders is not expedient. The guidance does not refer to the peak traffic load but the average traffic load. Accordingly, shoulders should be provided only above an average traffic load of 110,000 motor vehicles per day. The special cross section can safely accommodate an average traffic load of 65,000 motor vehicles per day as projected.

Even though the planning approval procedure has reached a far advanced stage, the Ministry should not rule out replanning. Contrary to the Ministry’s original assumption and due to numerous objections, plan approval may likely be delayed until year-end 2018. Against this background, replanning will not result in major time overruns.

© 2019 Bundesrechnungshof