Oslo S-Eidsvoll · 1992 to today
The airport railway and the delayed opening of Romeriksporten
Gardermobanen was planned as a fast, direct connection between central Oslo and the new airport. Most of the railway opened with the airport in 1998, while Romeriksporten remained closed until August 1999.
The airport and railway were one decision
Parliament approved the Gardermoen project on 8 October 1992. The railway was not an optional later addition: the airport plan depended on a fast, high-capacity link able to bring a large share of passengers directly from central Oslo. 01 02
The result was a 64-kilometre electric railway built for passenger speed rather than as a simple branch from the older network. Direct airport trains cover Oslo S-Gardermoen in 19 minutes, and the line permits 210 km/h across much of its length. 01
Romeriksporten was the shortcut
The double-track tunnel from Etterstad to Stalsberg removed the slower surface route around Groruddalen from the airport journey. The main tunnelling contract was signed on 1 June 1994, with excavation, railway systems and trial running scheduled to finish before the airport opened on 8 October 1998. 02
Planning documents treated large harmful leaks as unlikely. Yet consultation comments had warned about groundwater, Lutvann and drainage beneath Østmarka. The later government evaluation concluded that risk work had focused too narrowly on the probability of a leak and had not fully examined the consequences if one occurred. 02
Groundwater and Østmarka
A manageable tunnel leak could still damage the landscape
Water entering the tunnel could be pumped away, but the falling groundwater level affected lakes, streams, soil and vegetation above. 02
The tunnel began draining the landscape
On 3 February 1997, a sharp fall in Nordre Puttjern was reported. Water was entering the tunnel through fractured rock and lowering groundwater above it. The inflow was not a threat to the tunnel itself; it could be pumped and drained away. The environmental problem was the loss of groundwater feeding lakes, streams, soil and vegetation in Østmarka. 02
The project accepted responsibility, but months passed before the problem received a full response. At the same time, relations between client and contractor had deteriorated over progress and payment. On 22 March the contractor stopped work with about 500 metres of rock left. The government evaluation later connected that conflict and schedule pressure with the slow response to Puttjern and the preference for progress over time-consuming pre-grouting. 02
The attempted seal created a second crisis
Rhoca-Gil was used as a chemical supplement where cement grouting did not make the rock sufficiently tight. The product depended on curing in place. In flowing water, or when used in large wet cracks and improvised mixtures, unpolymerised acrylamide and N-methylolacrylamide could wash out with the drainage water instead. 02
Tests on 7 October 1997 found 140 micrograms of acrylamide and 42 micrograms of methylolacrylamide per litre in tunnel drainage. The government evaluation recorded that about 340 tonnes of Rhoca-Gil had been used, including roughly 85 tonnes of toxic components. Tunnel work was stopped while the discharge, worker exposure and surrounding environment were investigated. 02
Later tests found measurable neurological effects
The 1999 government evaluation recorded skin irritation among some workers but said the investigations available at that time had not detected nerve damage. It also reported no spread of acrylamide through groundwater to the public and only limited, non-lasting effects in the Alna river system. Those were findings at a specific point in the investigation, not the end of the worker-health record. 02
STAMI's 2002 study compared 25 exposed workers with 50 unexposed tunnel workers. Four months after exposure, the exposed group had significantly slower mean sensory nerve conduction in the ulnar nerve and a longer distal delay. Both measurements improved significantly when repeated one year later. 05
The rescue moved back to cement
Expert groups selected systematic post-grouting as the main remedy: closely planned drilling followed by microcement injected at high pressure. Watertight concrete lining and steel lining remained the more certain fallbacks if trials failed, while water infiltration was developed as an additional way to protect the groundwater balance above the tunnel. 02 03
The work concentrated on the leaking Puttjern and Lutvann zones. Final environmental decisions allowed maximum inflows of 400 litres per minute in the Lutvann zone, 220 at Puttjern and 300 at Puttjernsbekken, combined with monitoring and mitigation. By early 1999, independent review concluded that the water balance and groundwater situation were acceptable for opening. 02 04
The airport opened before its direct tunnel
The original tunnelling contract was about 541 million 1998 kroner, followed by 90 million awarded in arbitration. The government evaluation calculated a further 1.3 billion 1998 kroner for extra sealing, the prolonged construction period, consequential costs, contingency and VAT. 02
On 8 October 1998, Oslo Airport and the rest of Gardermobanen opened. Airport trains used Hovedbanen between Oslo and Lillestrøm while Romeriksporten remained closed. The tunnel entered service on 1 August 1999, about ten months after its original target. The evaluation also stressed the scale accurately: the severe problems were concentrated in roughly 500 metres, while most of the rock tunnel had advanced broadly to plan. 02 04
Gardermobanen today
Gardermobanen now carries airport expresses, regional services and long-distance trains between Oslo and Trondheim. Aviation-fuel trains are its regular freight exception. The last four-kilometre single-track bottleneck between Venjar and Eidsvoll received a second track in 2022; the wider 13.5-kilometre Eidsvoll-Langset project was formally completed in 2023. 01 07
After more than twenty-five years in service, Bane NOR began a major renewal of Romeriksporten covering track, power, drainage, water and frost protection and other technical systems. Work continues through 2028. 06
The project in time
From the 1992 decision to renewal
Parliament approves the project
The new main airport and its fast railway connection are authorised as one national project.
Romeriksporten contract signed
The main tunnelling contract begins with a planned opening on the same day as the airport.
Puttjern drops
The first reported fall in Nordre Puttjern shows that tunnel inflow is draining groundwater beneath Østmarka.
The original contractor stops
A severe contract conflict stops work with roughly 500 metres of rock still to excavate.
Breakthrough
The tunnel heading finally breaks through, but the water problem remains unresolved.
Rhoca-Gil crisis
Acrylamide is detected in drainage water and all tunnel work is stopped while the exposure and discharge are investigated.
A new sealing strategy
Systematic high-pressure post-grouting with microcement is selected as the principal remedy.
Airport and railway open
The airport and most of Gardermobanen enter service; airport trains use Hovedbanen while Romeriksporten remains closed.
Romeriksporten enters service
The direct tunnel route opens around ten months after the original target.
STAMI publishes the worker follow-up
The study reports measurable neurological effects after exposure and significant improvement in key measurements one year later.
The Eidsvoll bottleneck disappears
New double track opens through Eidsvoll and continues north to Langset.
Romeriksporten is renewed
Track, drainage, water and frost protection, power and technical systems are renewed after more than 25 years in service.
Sources
The railway, the leak, the exposure and the repair
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