A3075 Cubert Crossroads Improvement Scheme

Background

In 2015 we committed to developing design options for improving the junction into Cubert from the A3075; known locally as the Cubert Crossroads.

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We presented the preferred option of a roundabout, and the options which had been considered at two drop-in exhibitions in December 2015; one in Cubert and the other at St Newlyn East.

People were invited to tell us what they thought of the preferred option by completing the feedback questionnaire.

330 people completed the questionnaire, with 95% stating that they supported the proposal.

Because of the strong support for the roundabout option the council funded the preparation of a business case for the project. A business is essential to secure Government funding to both design and construct the scheme. It includes demonstrating the: need for the new junction, construction costs and the benefits.

In January 2017 we produced an outline business case for the roundabout option costing £4.9 million. To assess the value for money of a proposed scheme we look at the benefits it would deliver versus the construction cost. This ‘Benefit-Cost Ratio’ (BCR) should be 2.0 or more to be considered good value for money. We also looked at the impact that the A30 Chiverton Cross to Carland Cross improvements would have on the scheme:

  • with the A30 improvements happening the BCR is -0.3 due to improved journey times.
  • based on the A30 improvements not happening the BCR ratio drops to -2.18.

As neither option represents good value for money, and is therefore unlikely to receive funding, we considered the benefits-cost ratio for single lane dualling. This would provide a new central island on the A3075 similar to that on the A30 at Chybucca. Whilst this is cheaper at around £3.5 million as detailed in the business case for the single lane dualing it still doesn't represent good value for money:

  • with the A30 improvements happening the BCR is 0.201.
  • based on the A30 improvements not happening the BCR drops to -0.812.

Due to the low Benefit-Cost Ratios for both the roundabout and single lane dualling we're unlikely to attract external funding as:

  • Neither of the schemes un-lock significant levels of economic growth.
  • The schemes provide a limited contribution towards the Council’s overall transport aims. 

We're continuing to explore ways in which we can move this project forward and please revisit this page for updates.