Corrosion from road salt had left the Dartford Tunnel's eastern bore road deck with some pretty hefty latent defects when it was taken over as one of the earliest and most high profile private finance infrastructure projects. Replacing the entire reinforced concrete structure with something that would prove more durable than the original and without interrupting traffic was a major challenge.
Reconstruction contractor Kvaerner Construction won the keenly bid job from five rivals. The company's team proceeded to tear out and replace one of the most intensively used bits of road in Britain, barely noticed by the general public. Late night after late night the contractor went into the tunnel to prop the deck, saw right through, lift out a 4.5m length of roadway, lift in a replacement cast with corrosion resistant 60% slag cement, even up the road surface, and reopen - allowing 40,000 vehicles to roar through unhindered before the next night's work began.