Scilly Isles Junction

The area while the Kingston bypass was under construction

Scilly Isles is the southwestern terminus of the Kingston bypass (formerly A3). Today it forms the junction between the A307 and A309. Its design merges the A307 and A309 traffic from the north and west so that they form one entry and one exit onto the old A3 route.

History

There was originally just a minor junction with a side road leading to Thames Ditton. The opening of the Kingston Bypass in 1927 transformed it into Siamese roundabout that exists today. It is believed the A307 to Hampton Court was built around the same time.

Big changes to the junction were to occur in the 1960s when the Esher Bypass was being planned. Two routes for the bypass were studied in detail. One route was to follow the River Mole and would have been a westward continuation of the Kingston Bypass from the Scilly Isles. The other was the Commons Route which runs to the south of Esher. Either route would have had a big impact on the Scilly Isles as we will discover.

River Mole Route

The chosen layout

As mentioned, this route would have extended the Kingston Bypass westwards to pass over the Scilly Isles on its way to rejoin the A3 near Cobham via the River Mole. Slip roads would connect the A3 either side of the roundabout. Two alternative layouts were produced with extra flyovers to remove additional traffic from the roundabout. The layout shown on the final plans features just the flyover carrying the A3 over the roundabout.

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Alternative designs to remove additional traffic from the roundabout. Neither was pursued.

Commons Route

Layout of the enlarged junction with the link road at the bottom

This route leaves the A3 at Hook Junction and passes south of Esher to rejoin the A3 at Cobham and is what was built. Therefore it goes nowhere near the Scilly Isles. However, this isn't the end of the story. The county council was planning a link road because a bypass to the south of Esher would mean a large amount of traffic would still be travelling through the town. The link road would join the Scilly Isles to the A3 at Esher Common. The Scilly Isles would be considerably enlarged to become a five arm roundabout. An alternative layout shows the link road continuing over the roundabout to merge onto the A307 from Kingston. This was expected to be the link road's main traffic flow but the basic roundabout without the flyovers was accepted as the final design. The link road was never built due to environmental concerns and community opposition. The result is the Scilly Isles remains unchanged since it was first built in 1927.

Alternative layout with flyovers

Routes

Route	To	Notes
A309	Staines, Hampton Court	There is a height restriction of 15'6" just west of the Scilly Isles.
A309	London, Sutton, (A3)
A307	Esher, Guildford	In brown; Sandown Park
A307	Kingston	There is a height restriction of 13'3" just north of the Scilly Isles.
A3	London, Sutton	now A309
A3	Esher, Guildford	now A307
A239	London, Sutton	provisional number for the bypass
A3063	Kingston	Former A3 through Kingston until bypass opened
ELR	Guildford, (A3)