Switzerland is calling for rapid cooperation with the European Union to redirect traffic through other countries following the Gotthard tragedy.
Swiss alpine passes cannot handle heavy commercial traffic, said Michel Egger, deputy head of the Federal Office for Roads.
He is a member of the Swiss crisis team set up in response to the accident, which occurred on Wednesday when two trucks collided in the Gotthard tunnel, on a main European north-south route.
The accident triggered an inferno that left 11 dead, and forced the closure of the tunnel, for at least two or three months.
"The San Bernardino, Simplon and St Bernhard will not be able to cope with the additional traffic," Egger said.
Hans Werder, general secretary of the Federal Office for Transport, who heads the Swiss crisis team, said it will analyse the accident's consequences, and find ways of diverting the cargo traffic.
Some 3,600 trucks normally pass through the Gotthard daily, and industry sources say 80 per cent of cargo travelling from Italy to northern European airports goes through the tunnel.
Switzerland's national railway company, SBB, and a regional carrier, BLS, meanwhile, have decided to double their transport capacity respectively through the Gotthard and Lötschberg tunnels.
It is the first time in 20 years that the SBB has proposed a road-to-rail transfer for cars at the Gotthard.
The frequency of trains at the Gotthard is expected to rise from the current 10 per day to 28 within the next week and a half.
In addition, the SBB says it is increasing the capacity of passenger trains.
An alternate road through Switzerland was temporarily blocked on Thursday, when another truck accident occurred near the San Bernardino tunnel. One person was killed in that crash.
The San Bernardino tunnel was reopened several hours later.
swissinfo with agencies
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