Channel Tunnel terms of the Concession, Eurotunnel was obliged to investigate a cross-Channel road tunnel. In December 1999 road and rail tunnel proposals were presented to the British and French governments, but it was stressed that there was not enough demand for a second tunnel. A three-way treaty between the United Kingdom, France and Belgium governs border controls, with the establishment of "control zones" wherein the officers of the other nation may exercise limited customs and law enforcement powers. For most purposes these are at either end of the tunnel, with the French border controls on the UK side of the tunnel
Channel Tunnel train's winterisation shields, and the transition from cold air outside to the tunnel's warm atmosphere had melted the snow, resulting in electrical failures. One train was turned back before reaching the tunnel; two trains were hauled out of the tunnel by Eurotunnel Class 0001 diesel locomotives. The blocking of the tunnel led to the implementation of Operation Stack, the transformation of the M20 motorway into a linear car park. The occasion was the first time that a Eurostar train was evacuated inside the tunnel; the failing of four at once was described as "unprecedented". The Channel Tunnel reopened the following