Construct - Issue 49

The largest area of SuDS is in the middle of the roundabout, where a rain garden was created using tiers of gabions to hold and slow down the flow of water. Planting contributes to this attenuation, as well as enhancing the environment for pedestrians and cyclists and helping to improve air quality. Together, the SuDS measures on the project can collect run-off from over 6,000m 2 of road surface and delay it getting into the sewers during high rainfall. The planting also filters out pollutants, so the run-off is cleaner when it eventually reaches the sewer system. As well as widening the Kingston Road, the new layout creates additional capacity on the roundabout by utilising space in the outer lanes that was previously closed to traffic because the parapets did not meet modern safety standards. FM Conway has replaced them with a new, higher, parapet system consisting of a reinforced concrete base topped with steel barriers. Work to demolish the old wall and build the new parapets was carried out while traffic continued to flow, thanks to the installation of an encapsulation system constructed of scaffolding wrapped in polythene. “We had to construct the new parapet system on top of the existing bridge structure, but we had to make sure we didn’t damage that structure,” explains Philip. “Instead of using traditional heavy equipment for demolition, like peckers and breakers, we opted for hydro-demolition, which uses high-pressure water jets to cut away the concrete.” “We had to construct the new parapet system on top of the existing bridge structure”

TOLWORTH ROUNDABOUT

Key:

TOLWORTH BROADWAY

EWELL ROAD

Signalised pedestrian crossings

BUS STOP

BUS STOP

Raised tables Cycle lane Existing kerbline removed

BUS STOP

Improved road markings

TOLWORTH RISE NORTH

CLEAR

CLEAR

KEEP

CLEAR

KEEP

KEEP

BUS STOP KINGSTON BYPASS

BUS STOP

SURB SURB A3(N) A3(N) EWELL

EWELL

BROAD OAKS

Improved road markings

SURB A3(N) A3(N) EWELL

CLEAR

EWELL

KEEP

KEEP

CLEAR

Landscaping and rain gardens

CLEAR

KEEP

TOLWORTH UNDERPASS

KEEP

CLEAR

SURB

SURB

A3(S)

EWELLEWELL

Improved crossing

Existing subway access closed

KEEP

KEEP

CLEAR

CLEAR

KEEP

CLEAR

HOOK RISE NORTH

KINGSTON BYPASS

New uncontrolled crossing to access subway

KINGSTON ROAD

Existing subway access closed

HOOK RISE SOUTH

Hollywood Bowl

BUS STOP

Additional traffic lane to improve access to A3

KEEP

CLEAR

New shared area for cyclists and pedestrians

TOBY WAY

NEW HOUSING DEVELOPMENT

DONALD WOODS GARDENS

Tolworth Rail Station

3-TIER ASSESSMENT

During the Tolworth project, FM Conway’s site works were assessed under process, which aims to ensure that road users of all abilities can get around easily while works are under way. The first two tiers cover pre-design TfL’s 3-Tier Assessment

and design, while Tier 3 looks at the accessibility of temporary layouts. “When Michael Barratt MBE [the assessor] came to site, it gave us a very good insight into what you have to consider as a member of public, for example if you rely on a

wheelchair or on tactile surfaces,” says Philip. The approach has gained industry recognition as a finalist at the CiTTi and Highways Awards, with FM Conway now looking to adopt the assessment process on all its projects in future.

All the major works were completed in April 2024.

10