Editing A30 road (section)

===London to Honiton===
The A30 begins at Henlys Roundabout, where the route stems from the [[A4 road (England)|A4]] near [[Hounslow]]. It crosses the [[A312 road|A312]] before running south of the Southern Perimeter Road, [[Heathrow Airport]] and north of [[Ashford, Surrey|Ashford]] and [[Staines-upon-Thames]], before reaching the [[M25 motorway]] orbital motorway. This first section is entirely dual carriageway.  Taken with the A4, its natural continuation which nearby becomes non-dualled towards the M25, the section constitutes one of five routes into the southern half of London which reach Inner London with at least a dual-carriageway, the others being the [[A3 road|A3]], the [[M3 motorway (Great Britain)|M3]], the [[M20 motorway|M20]] and [[A2 road (Great Britain)|A2]], however approximately one mile before reaching [[Hammersmith and Fulham|Inner London]] it is combined with the London variants of the M3 and M4 approaches.

After running astride the M25 to cross the [[River Thames|Thames]] on a bridge designed by [[Edwin Lutyens|Lutyens]], the [[Runnymede Bridge]], the A30 runs parallel to but distant from the M3 until southwest of [[Basingstoke]], bypassing [[Egham]] and passing through  heathland and [[Sunningdale]], [[Bagshot|Bagshot bypass]], and [[Camberley]] where the route almost mirrors the [[Devil's Highway (Roman Britain)|Devil's Highway]], a stone (''stane'') street to [[Calleva Atrebatum]] (Silchester Roman town), believed to be older still, then passes close to [[Hook, Hart|Hook]] town centre and in the surrounding country the soil is arable.

After the 1930s Basingstoke bypass, the M3 changes direction (between [[North Waltham, Hampshire|North Waltham]] and [[Popham, Hampshire|Popham]], at the Popham Interchange) the A303 takes over for {{convert|2|mi}} the A30 losing continuity.{{efn|From [[North Waltham, Hampshire]] to nearby Micheldever Station, the A30 is subsumed into the A303 and one version remains so until [[Sutton Scotney]]/Bullington, the intersection with the Oxford (etc)&mdash;Southampton road, the A34, from where the A30 revives running south along Bullington Lane almost alongside the A34 before resuming a direct west south-westerly route to Salisbury and beyond; however along this combined A303-A30 section at Coxford Hill above [[Micheldever railway station]] an original version branches off linking more directly Sutton Scotney village from that point and enabling a cycle route to avoid Popham and the dual carriageway, taking a detour through North Waltham village.}}  From Sutton Scotney village the A30 runs parallel to the latter road [[geodesic datum|as-the-crow-flies]] {{convert|85|mi}} to north-east of Honiton, Devon passing through towns [[Stockbridge, Hampshire|Stockbridge]] (where it meets its first substantive river since the Thames, the [[River Test|Test]]) and its trout fishing centres, [[Shaftesbury]], [[Sherborne]], [[Yeovil]], [[Crewkerne]] and [[Chard, Somerset|Chard]]. Between Stockbridge and Shaftesbury it enters the cathedral city of [[Salisbury]].

Between the M25 and Honiton, the A30 is mostly single carriageway, carrying local traffic with short stretches of dual carriageway from Camberley to Basingstoke, which has a dualled inner ring road, two between Stockbridge and Salisbury (an alike ring road shared with the A36), and between Sherborne and Yeovil.