Investigation into the potential for economic optimisation of tunnel drainage

At Ruhr University Bochum (RUB), key principles for calculating and evaluating life-cycle costs (LCC) of tunnel structures have been developed. The work carried out by Adden and Vogt forms the basis for current recommendations issued by the German Committee for Underground Construction. In addition, a forecasting model for estimating construction costs for road tunnels was developed as part of the BASt project FE 15.577/2012/ERB. The findings from that project are to be used in the present project to validate and carry out an economic assessment of cost estimates for drainage systems.

The project focuses on the integrated assessment and economic optimisation of longitudinal drainage systems in road tunnels and adjacent trough structures. The systems must reliably drain surface water during normal operation whilst, at the same time, ensuring a high level of safety in the event of exceptional incidents, such as accidents involving hazardous goods or fires. Furthermore, it must be possible to operate, clean, service and maintain them reliably over decades.

The aim of the project is to develop a robust and practical basis for decision-making regarding the selection of technically equivalent and economically optimised drainage systems. In addition to conventional solutions, particular attention is being paid to systems featuring culverts arranged within slotted channels. The assessment takes into account the interactions between hydraulic performance, safety, operation, durability, availability and cost-effectiveness. A key focus is on hydraulic performance during normal and emergency operation. In addition to normal surface runoff, increased inflows, fire-fighting water and liquids resulting from hazardous materials incidents are considered. For trough structures, specific rainfall and heavy rainfall events are also investigated. Furthermore, the system’s behaviour during fire and hazardous substance incidents is analysed. In culvert systems in particular, fire penetration, fire exposure and the effects of a failure or blockage of individual components are investigated. Numerical simulations and laboratory tests are used for this purpose. Another key focus is the life-cycle assessment. In addition to capital costs, operating, cleaning, maintenance and repair costs, as well as durability and availability, are taken into account. Necessary traffic closures and their impact on operations are also factored into the assessment. The project is expected to yield a structured evaluation framework, robust findings on hydraulic and safety performance, a life-cycle cost assessment, and practical recommendations for planning, construction, operation and maintenance. In addition, guidance on the further development of relevant technical regulations is to be drawn up.

Key points at a glance:

• Funding: BASt (Federal Highway Research Institute)
• Duration: 18 months
• Internal project managers:
  • Silvia Herrmann, M.Sc.