Vertical clearance of 5.03m is required over the full width of a carriageway in addition to a further 500mm at either side. In the event of a cross fall on the carriageway being greater than 2.5% (1-in-40), the 500mm dimension should be increased to 610mm on the low side of the carriageway.

The vertical clearance required at the entrance to a type G mews is 4.1m. If clearance is less than 5.03m, it must be signed. However, if separate service-vehicle access is provided, the clearance at the secondary entrance could be reduced to 2.25m.

Please note that for structures over type A roads, Design Manual for Roads and Bridges (DMRB) standards apply. Further advice should be sought from the Highway Authority.