Paragraph 4
The failure of rolling stock on the track caused by—
(a)
the failure or seizing of an axle;
(b)
the failure of a wheel or tyre, including a tyre loose on its wheel;
(c)
the failure of brakes on a train; or
(d)
a fire or severe electrical arcing or fusing on rolling stock, whether or not extinguished by a fire-fighting service.