Highways Agency - Safe roads, Reliable journeys, Informed travellers

Related pages

• 1. introduction
• 2. scheme proposals
• 3. engineering assessment
• 4. environmental assessment
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 4. environmental assessment (continued)
• 5. traffic and economic assessment

2. scheme proposals

2. Scheme Proposals

2.1 Description of the CHUMMS Strategy

The CHUMMS Strategy is identical to the Orange Route Option with Junction Strategy B as discussed in SAR Part I. Therefore reference should be made to SAR Part I Volume I Part A Section 3.1.4.

2.2 Description of the Alternative Proposal

2.2.1 A14 Mainline

As can be seen from Figure 2.1, the Alternative Proposal follows the same route as that of the CHUMMS Strategy, shown in Figure 3.5 of Part I Volume I Part A of the SAR. The proposal commences to the west of the existing Brampton Hut Junction with the A1. From here it travels adjacent to the west of the A1 and in doing so maintains one corridor of traffic in this area.

After crossing the A1 between Brampton and Buckden the Alternative Proposal passes to the south of Buckden Landfill Site before crossing the River Great Ouse and East Coast Mainline railway. It continues eastwards to the south of the Wood Green Animal Shelter and north of the villages of Hilton and Conington. It then passes to the south of Fenstanton and the closed Conington Landfill Site prior to tying into the existing A14 to the south of Fen Drayton.

From this point the Alternative Proposal is identical to the CHUMMS Strategy, comprising widening of the existing A14 and the Cambridge Northern Bypass (CNB) to Fen Ditton, with the exception of a short section at Bar Hill. At this location the route moves offline to the north of Bar Hill, between Lolworth Spring and the Girton Interchange by a distance of 110 metres at its maximum point to allow a new junction to be constructed to replace the existing one.

In locations, where the existing A14 is widened, provision will be made for local traffic in the form of a Local Access Road (LAR). In most areas the LAR runs adjacent to the proposed A14 and ties into the existing A14 when the route moves offline at Fen Drayton. The existing A14, west of Fen Drayton will be maintained as a strategic route carrying east-north traffic flows while the proposed offline section will carry east-west and east-south traffic flows.

2.2.2 Junction Strategy

As with the CHUMMS Strategy, the Alternative Proposal has nine associated junctions, as listed below:

• Brampton Interchange
• Fen Drayton Interchange
• Trinity Foot Junction
• Bar Hill Junction
• Dry Drayton Junction
• M11 Junction 14 Histon Junction
• Milton Junction
• Fen Ditton Junction

A description of these junctions is provided in Section 3.2.2 where they differ from those detailed in Part I of the SAR for the CHUMMS Strategy.

Figure 2.1 - Alternative Proposal Mainline

2.3 Cost Estimate

2.3.1 Basis of Estimate

As mentioned briefly in Section 1.2, since the various route options were reported on in SAR Part I, the capital costs of the CHUMMS Strategy was subjected to an internal 'scheme challenge'. This challenge involved a 'top down' comparison of the scheme cost estimate against available out-turn costs for similar completed schemes for which Atkins had access to detailed cost information. (This approach was adopted to provide a contrast to the 'bottom up' approach used to derive the cost estimates). The process also entailed a detailed review of the additions made to the cost estimates to represent:

• preliminaries and traffic management;
• preparation and supervision;
• optimism bias;and
• risk.

The challenge resulted in a reduction in the estimated cost of the CHUMMS Strategy. This means that the costs included in this report are lower than those attributed to the same scheme in Part I of the SAR (where the option is reported as the Orange Route Option with Junction Strategy B). The earlier, pre-challenge costs have been retained in Part I of the report to provide consistency between the costs of the Orange Route Option and those attributed to the other options (Blue and Purple Routes and options involving Junction Strategy A) which have not been subject to the same cost challenging exercise. Table 2.1 below summarises the costs estimated for the CHUMMS Strategy together with those estimated for the Alternative Proposal.

As explained in SAR Part I, the costs in Table 2.1 are estimated to third quarter 2001 (Q3/2001) to enable them to be readily compared to the Highway Agency's current Scheme Budget and previous estimates prepared for the HA.

2.3.2 Comparison of Estimates

The Alternative Proposal has a reduced carriageway width to that of the CHUMMS Strategy between Brampton and Fen Drayton with corresponding cost savings in earthworks and pavement. The narrower deck widths of the River Great Ouse viaduct and the Brampton Interchange structures that result from this also produce cost savings. There is however, additional cost associated with the requirement to provide accommodation tracks adjacent to the existing A14 in the Alternative Proposal to minimise direct farm access onto the existing road. This is discussed in more detail in Section 3.2.1.

The requirement to replace the Huntingdon Viaduct by 2012 is not altered by the Alternative Proposal and therefore no costs for viaduct work have been included in the cost estimate for this scheme.

Reference should be made to Table 3.1 in Appendix A of Volume I Part B, which lists the above engineering parameters for both the CHUMMS Strategy and the Alternative Proposal.