One of the aims of the design study is to produce a detailed costing of the TLEP project. Not surprisingly, the main cost drivers for the whole complex are expected to be the tunnel, the shafts and the related services and infrastructure (including access roads). The TLEP project, however, may be considered as a precursor to the VHE-LHC, in which case the corresponding cost would be shared between TLEP and the VHE-LHC. The length of the tunnel will be optimized on the basis of geological and accessibility criteria. For example, a tunnel of 100 km (also shown in Fig. \ref{fig:TLEP80}, and for which a feasibility assessment is ongoing) might be more cost-effective than the 80 km version \cite{OsbornePrivate}.

Besides, the cost of the accelerator and collider rings, dominated by the 600-m-long RF system and the 80 km of low-field magnets – possibly recyclable for the VHE-LHC injector – was found in a very prelimimary estimate to be smaller than the LHC cost (Table \ref{tab:cost}). In view of the large number of Higgs bosons, Z and W bosons, and top quarks to be analysed in very clean experimental conditions, TLEP is therefore expected to be exceedingly competitive.