Permitted deviation within limits

4.  In constructing or maintaining the railway the Company may—

(a) deviate laterally from the lines or situations shown on the deposited plans within the limits of deviation shown on those plans; and

(b) deviate vertically from the levels shown on the deposited sections—

(i) to any extent not exceeding 3 metres upwards; and

(ii) to any extent downwards as may be necessary or expedient.