Felixstowe, not Folkestone? The latter is where the channel tunnel is, which does account for a lot of freight but you probably meant the container port at Felixstowe. I used to drive on the A14 daily and you could tell when a ship had recently arrived by the number of containers on the roads. The road also suffered badly from "tram tracks" due to large numbers of heavy good vehicles. Crazy when you realise a lorry can take one container while a single train can take a hundred or more.