Traffic Future Region Thun, Work Package 3: urban spatial, traffic, constructional, and environmental planning feasibility study of two tunnel variants

Work Package 3: In-depth urban spatial, settlement spatial, traffic, constructional, and environmental planning feasibility study for the two tunnel solutions "Hübelitunnel" and "Aarequerung Süd" (General Planner). The project "Verkehrszukunft Region Thun" builds on the "Verkehrsstudie Thun Innenstadt – rechte Seeseite" (Traffic Study Thun City Center – Right Lake Side), which was prepared for the Thun Development Area by the end of 2023. Three variants were examined for the long-term improvement of the traffic situation: the Hübelitunnel, the Aarequerung Süd, and a comprehensive traffic variant with traffic controls and expansions for public transport and bicycle traffic. All variants are generally considered feasible; however, the comprehensive traffic variant was evaluated as the most cost-effective and efficient solution. Should this not be sufficient, the two tunnel variants are to be examined in more detail. In discussions regarding potential co-financing, the federal government emphasized that a tunnel project must not be considered in isolation but must be embedded in a convincing overall concept. Key aspects are the coordination of settlement and traffic development, the impact on urban development and jobs, integration into the overall traffic system, and flanking measures. The benefits of the variants must be demonstrably presented using the criteria of the agglomeration programs. Furthermore, a clearly justified variant decision is required, showing that other options have been exhausted and the chosen solution is broadly accepted. The region follows this recommendation and is examining the two variants Hübelitunnel and Aarequerung Süd in parallel. The goal is a politically consolidated decision by the end of 2028 and technical integration into the 6th Generation Thun Agglomeration Program. The concerns of the population, politics, and administration of the affected municipalities are to be considered, and the variants are to be evaluated based on transparent qualitative and quantitative criteria. Alternative relief variants are not part of the project; however, the existing tunnel variants can be optimized or excluded if there are serious showstoppers. In addition to the technical evaluation, the project should enable public discourse on the opportunities, risks, benefits, and costs of a tunnel solution. This is not about a blanket tunnel-yes-or-no debate, but about a differentiated examination of traffic, urban planning, financial, and social impacts. The client is the Thun Development Area (ERT). Strategic management is carried out by the "Verkehrszukunft" committee. It decides on interim results, awards, and specifications. Operational project management leads the project. In addition, political, technical, and public advisory bodies will participate. Political accompaniment reflects interim statuses from a political perspective, technical accompaniment ensures coordination with parallel projects and technical requirements, and public accompaniment, in particular, allows those affected in Thun and Steffisburg to voice their concerns. The BHU or contractors from AP1 provide technical, organizational, and quality assurance support. The external contractors for work packages AP1 to AP4 provide services but have no decision-making authority. The project process is divided into four work packages: AP1 includes preparation, procurement, process support, and quality assurance; AP2 Participation and Communication; AP3 the in-depth feasibility study for the two tunnel variants; AP4 Target system, methodology, variant assessment, and recommendation of the best variant. The core steps AP4a (Target system, methodology), AP3, and AP4c (Variant assessment and recommendation) generally run sequentially. For both tunnel variants, at least one substantive planning stage is aimed for, which is subsumed under the term "feasibility study". In terms of planning depth, the services are in the area of SIA Phase 2 preliminary study. For individual aspects (e.g., construction process), more in-depth clarifications beyond the usual planning level of a preliminary study must be carried out to be able to make statements that achieve the goals of the feasibility study. For other aspects, coarser clarifications may be sufficient: — Definition of normal profiles and horizontal and vertical alignments (consideration of surface and underground obstacles) — Arrangement of portal areas and other accesses (impact on urban space) — Dimensioning of affected roads and intersections (space requirements) and specification of intersection control type (capacity) — Utilization of development potential in relieved areas (urban planning/settlement spatial) — Dependencies/interactions with third-party projects (influence, obstruction, phasing) — Flanking measures (traffic, design) — Construction process/procedure (incl. impact during construction) and construction time (duration) — Installation sites and construction/material logistics (space requirements, emissions) — Construction and operating costs (target +/- 25% incl. monetary opportunities/risks and reserves) — Strengths / weaknesses or opportunities / risks of both variants (holistic qualitative) — Preparation of and assistance with relevant technical work for participation/communication (clear plans and visualizations, textual explanations) For the investigation of different portal variants "West" of the Aarequerung, a preliminary phase is to be provided in which various alternatives to the currently planned location are roughly examined. Only the best variant from this preliminary investigation will then be examined and evaluated in detail with all other elements.