Trains could stop running on a key section from next month, leaving eight stations without a service. Particular problems could be caused at Barking, where many mainline train commuters change to the Tube. However, the disruption would spread along the entire line. Steve Grant, London district-secretary of Aslef, the train drivers' union, said: "Vandals are actually stockpiling bricks and paving slabs to hurl at trains. Unless something is done, and done now, a passenger or one of my members is going to be seriously injured or worse."