Technical feasibility and strategy updates are official, but formal construction approval awaits 2028
CERN delays mega collider funding decision to 2028
Member states face a 15 billion Swiss franc bill to build a particle tunnel three times larger than the current ring.
In a nutshell
CERN has chosen a 91-kilometer, 15 billion Swiss franc underground ring as its preferred next-generation particle collider, but its realization depends entirely on a high-stakes funding vote by member governments around 2028.
Highlights
- The proposed circular tunnel spans 91 kilometers beneath the border of France and Switzerland.
- Building the first-phase electron-positron collider carries an estimated cost of 15 billion Swiss francs.
- Private donors pledged 860 million euros in late 2025 to fund exploratory development.
- Member states on the CERN Council will cast a binding vote around 2028 on whether to fund construction.
Planned collider circumference
kilometersThe findingThe proposed Future Circular Collider would be more than three times the size of the existing ring.
- A comparison of the underground tunnel circumference of CERN's current collider against its proposed successor.
- Large Hadron Collider — CERN's existing 27-kilometer underground particle accelerator
- Future Circular Collider — CERN's proposed 91-kilometer next-generation particle accelerator
- The scale determines how many collision points and energy levels scientists can reach, setting the scope of the 2028 funding debate.
From the Editor’s Diary
Mega-science projects are ultimately governed by government finance rather than technical feasibility, leaving scientific discovery vulnerable to national budget cycles.
Who's involved
CERN Council
The supreme governing authority of CERN composed of representatives from member states
goal → Wants to balance scientific ambition against multi-billion euro national budget contributions
CERN Management
The executive leadership team of the laboratory headed by Director-General Mark Thomson
goal → Seeks approval, partner funding, and seamless succession planning after the LHC shuts down
Host States France and Switzerland
The two neighboring nations whose territory would house the 91-kilometer underground tunnel
goal → Seek environmental compliance, public consensus, and regional economic returns
In short
CERN has set a definitive 2028 deadline to decide whether to build a successor to the world's largest atom smasher, leaving the future of European high-energy physics hanging on national budgets. The European Organization for Nuclear Research, known as CERN, plans to dig a 91-kilometer circular underground tunnel beneath the Franco-Swiss border to study the Higgs boson, the fundamental particle that gives mass to matter, and hunt for phenomena beyond the established rules of physics.
The plan makes an initial construction approval vote by European governments the critical test for global particle research in 2028.
Approval remains highly uncertain because member nations must commit to an estimated construction cost of 15 billion Swiss francs, or around 16 billion euros, spread over 12 years during a period of strained public finances.
How it unfolded
European strategy mandates collider feasibility study
CERN member states formally launched the quest to find a successor to the Large Hadron Collider, ordering an in-depth investigation into whether a larger circular ring was technically and financially viable.
Delivery of the 91-kilometer feasibility blueprint
Five years of engineering assessments turned an abstract proposal into a concrete 90.7-kilometer ring design, establishing the first formal price tag and testing the appetite of European paymasters.
Strategy adoption and advancing to the 2028 vote
Fresh private backing helped CERN leadership push the project onto the political agenda, prompting member governments to confirm the collider as their top priority while locking in a hard deadline for the final build decision.
Where things stand
The Future Circular Collider is undergoing environmental reviews and public debate across France and Switzerland following its May 2026 strategic endorsement. Laboratory milestones, including deep-freeze tests of prototype magnets, continue as independent research rather than licensed construction.
The decisive obstacle comes around 2028, when the CERN Council must vote on binding national cash quotas and international treaties before excavators can break ground in the 2030s.