Engineering work taking place on the 16th February 2008. As you can see there is major work on the District and Piccadilly lines west of Hammersmith. Meaning Heathrow loses its Tube connection to Central London. Making the Hex (Heathrow Express) people very happy! The west legs of the DLR are also closed. As seems to be standard for February the Jubilee north of Wembley Park is closed as well.
Please note that this map is not offical but more my own work.