Highways Agency

A428 Caxton Common to Hardwick Improvement

6.0 Description of the scheme

6.1 The Scheme would provide a dual carriageway improvement. Traffic would only be able to join or leave the dual carriageway at Caxton Gibbet roundabout, at the new junction at Cambourne and at the new junction proposed at Hardwick. The existing trunk road would be retained for local traffic between Cambourne and Hardwick. The Scheme is shown on Figure 3.

Caxton Gibbet to Cambourne

6.2 The proposed route of the Scheme would begin at Caxton Gibbet roundabout (which is lit) and follow a right hand bend to the north of the existing road, passing the stopped-up Elsworth Road. It would tie into the Cambourne dual carriageway approximately 990 metres east of the roundabout. A small part of the Cambourne dual carriageway would be realigned. Only minor alterations would be made to the existing Caxton Gibbet Roundabout to provide for the dual carriageway.

6.3 Between Caxton Gibbet and the Elsworth Road, the proposed route would be at or very near existing ground level. Between Elsworth Road and the Cambourne Dualling the proposed route would be on a low embankment, less than 2 metres high.

6.4 Part of the existing trunk road near Caxton Gibbet would remain in place and be connected to the A1198 Royston Road south of the existing roundabout to provide access to property south of the new trunk road. Some of the existing trunk road would be removed.

6.5 A balancing pond would be located in the space between the proposed route and the existing road. This would provide a floodwater storage area in the event of heavy rain. Adjacent to the balancing pond, an area of mounding up to 2.5 metres high would provide a buffer for properties on the south side of the existing road. Also in this area and to the north of the proposed route planting would be established to provide a buffer between properties and the proposed route and to screen the proposed route in views from the north.

6.6 A proposed cycleway/footway on the north side of the planting would provide a link between the A1198 Royston Road and the Elsworth Road.

Cambourne to Hardwick

6.7 East of the Cambourne dual carriageway, the proposed route would stay on the south side of the existing road curving right and then left to pass south of the reservoir by the Broadway. Part of the Cambourne dual carriageway would need to be realigned. A new balancing pond would be constructed on the north side of the existing road opposite the Cambourne Development, adjacent to New Inn Farm.

6.8 The proposed route would be in a shallow cutting and cross the Broadway approximately 100 metres south and 150 metres west of the existing junction with the trunk road. A bridge over the proposed route would be provided adjacent to the reservoir to maintain the existing road network and connect the Broadway to the existing trunk road which would be raised slightly. The embankment slopes for the new bridge and the area between the old and new Broadway alignments would be planted.

6.9 The redundant section of existing carriageway at the end of the Broadway would be removed and the area seeded with a species rich grass mix.

6.10 Beyond the Broadway, the proposed route would be on a slight embankment whilst straightening to pass Two Pots Farm to the south. It would then curve north to cross the existing trunk road at existing ground level approximately 300 metres west of Childerley Gate. Continuity of the existing trunk road would be provided by a bridge over the proposed route at this point and this would maintain the local road network between north and south.

6.11 Planting to the north of the proposed route would provide a buffer between traffic and nearby properties and this would be augmented by an area of mounding up to 2 metres high near Two Pots Farm and Cottages and another up to 3 metres high near the properties at Childerley Gate.

6.12 The proposed route would continue to the north of Childerley Lodge in cutting up to 2 metres deep and cross the Childerley Estate access approximately 120 metres north of the present junction. Access to the Childerley Estate and to Bourn Airfield and associated industrial units to the south would be maintained from the existing trunk road by means of two private accesses.

6.13 Beyond the Childerley access the proposed route would run parallel to and north of the existing trunk road on a right hand curve to pass beneath a bridge on the line of Scotland Road approximately 100 metres north of the existing Hardwick roundabout. At this location the new dual carriageway would be in a cutting up to 8 metres deep. The existing Hardwick roundabout would be enlarged and a second roundabout to the north of the dual carriageway on Scotland Road would enable a full two level junction to be provided, allowing traffic to join and leave the dual carriageway from all directions. The roundabouts would be lit. The existing trunk road east of Hardwick roundabout would be removed and the area planted.

6.14 A temporary realignment of Scotland Road would be built to enable construction of the bridge.

6.15 A mound would be formed along most of the southern edge of the proposed route as it passes Hardwick and this would be planted. Two balancing ponds would be constructed to the south of the proposed route along this length. On the north side, a belt of planting would screen the road, junction and roundabouts in views from the north.

6.16 To the east of Scotland Road, the alignment would continue on a right hand curve to connect into the existing dual carriageway east of Hardwick. The current gap in the central reserve on the dual carriageway near Hardwick, and the access to Park Farm opposite would both be closed. An alternative access would be provided to the farm from Church Lane in Madingley.

6.17 A new footbridge would be provided connecting Footpath Number DD17 to St Neot's Road in Hardwick.

6.18 Lay-bys in each direction would be included in the Scheme.

6.19 The construction of the Scheme would result in an overall volume of excavated material to be taken off site of 117,000 cubic metres.

6.20 Cost estimates have been prepared for the Scheme. The total estimated cost of the Scheme (excluding VAT) at 2000 prices is: