5Nothing in an order made with respect to—
(a)a bridge owned by railway undertakers and crossing a rail way of the undertakers, or
(b)a bridge owned by canal undertakers and crossing a canal of the undertakers, or
(c)a bridge owned by dock undertakers, or by harbour undertakers, crossing a railway, lock, passage or other work of the undertakers,
shall, without the consent of the owners of the bridge, require the bridge to be altered or reconstructed in such a manner as to necessitate an alteration in the level, or reduction in the width, of the railway, canal, lock, passage or work, or to reduce the headway of the bridge as existing at the date of the order.