It was the Hatfield rail crash on 17 October 2000 that proved to be the defining moment in Railtrack's collapse. The subsequent major repairs undertaken across the whole British rail network are estimated to have cost in the order of £580 million. According to Christian Wolmar, author of "On the Wrong Line", the Railtrack board panicked in the wake of Hatfield. Because most of the engineering skill of British Rail had been sold off into the maintenance and renewal companies, Railtrack had no idea how many Hatfields were waiting to happen, nor did they have any way of assessing the consequence of the speed restrictions they were ordering – restrictions that brought the railway network to all but a standstill.