A27 Chichester Bypass Mitigation Supplementary Planning Document - August 2023

Planning Contributions

The A27 Chichester Bypass infrastructure to be funded

4.1 Section 2 above explained that due to the high costs and the absence of government funding, the full A27 Chichester Bypass mitigation package, involving improvements to Fishbourne, Bognor, Whyke and Stockbridge junctions, was not deliverable. Therefore, the Council has had no option but to propose a reduced mitigation package which will focus on delivering the improvements works to both Fishbourne and Bognor junctions, as described within Section 7 of the Local Plan Transport Assessment (Stantec, January 2023). These junction improvements are also set out within the Infrastructure Delivery Plan and the Infrastructure Business Plan.

4.2 The proposed infrastructure works at the Fishbourne and Bognor junctions is a higher specification compared to that originally proposed within the Transport Assessment that supported the adopted Local Plan. This change has been necessary as the original specification no longer sufficiently addresses the capacity problems that have been anticipated at those junctions through the latest modelling work reported in the 2023 Transport Assessment. This means that the costs for delivering these junction improvements has significantly increased compared to what was set out in the 2013 Transport Assessment and the 2016 SPD.

The cost of the infrastructure works

4.3 The revised specification for improvement works at Fishbourne and Bognor junctions has been independently costed, with the most recent information on costs being set out within Section 9 and Appendix J of the Local Plan Transport Assessment (Stantec, January 2023). The latest costs are also set out in the Council's Infrastructure Delivery Plan and the Infrastructure Business Plan.

4.4 The assessed costs have been subject to review by both National Highways and West Sussex Council County and are considered robust for the purposes of the preparation of the new Local Plan. The latest available costs are as follows:

• Fishbourne Roundabout with the Terminus Road Link (cost between £9.5 and £12.9 million); and
• Bognor Road Roundabout with the Vinnetrow Road Link (cost between £19.4 and £30.4 million).

(Total cost range: £28.9 - £43.3 million.)

4.5 These costs will inevitably change over time and prior to the commencement of any construction work, a rigorous assessment and design process would be required that would inform a final projected cost for each of the improvements works. However, that detailed process is not appropriate for the purposes of preparing a local plan or local guidance documents. Therefore, the above costings have been used for the purposes of calculating planning contributions, applying the upper end of the range shown to ensure that the level of funding will be sufficient to deliver the required improvements.

4.6 Within Section 5 below, there is also guidance on an appropriate 'Index-linking' procedure through which changes in the costs over time will be possible to capture, to the extent that these are impacted by general inflation in the costs of road construction projects.

4.7  As at the end of July 2023, £16,251,085 has already been secured towards the A27 mitigation works under the adopted SPD. This comes from development that has already been permitted since 2016 and also from schemes that have a 'resolution to grant' and also from the two existing Strategic Development Locations at West of Chichester (phase 2) and Tangmere. This means that an overall target of £27,068,915 currently remains to be secured from planning contributions collected under this SPD.

The level of development anticipated

4.8 As the full A27 mitigation package is not affordable, a 'reduced mitigation package' is likely to be progressed, given the need to fund the works solely through planning contributions. In the absence of the full mitigation package, the Council has needed to adopt an 'infrastructure constrained approach' to planning new homes within the south of the District. This is set out in more detail within the Chichester Local Plan 2021 – 2039: Proposed Submission Plan (February 2023).

4.9 As the new Local Plan has not yet be subject to Examination, it is not possible to be clear on exactly how much residential development within the south of the District will be acceptable to 2039 on the basis of the reduced level of mitigation proposed. However, the emerging Local Plan proposes a total level of development amounting to 9,630 dwellings (or an average of 535 per year) for the area south of the National Park.

4.10 This effectively places a ceiling or cap on the level of new homes coming forward. But that 'cap' does not only apply once the new Local Plan has been adopted. National Highways has indicated that it considers that the 'baseline' for assessing the impact on development coming forward on the A27 should start in January 2023, when the Council's modelling work on traffic impact was published within the Local Plan Transport Assessment. This means that any new dwellings coming forward now within the south of the District, whether planned or otherwise, will count towards the overall 'cap' on new homes.

4.11 It is important to note that a majority of the 9,630 dwellings referred to above (about 6,000) are already 'committed' which means they either have an extant planning permission or a 'resolution to grant' planning permission from the Council's Planning Committee. These homes (which include the two Strategic Development Locations being taken forward from the adopted local plan) will not be impacted by this SPD, although they will have contributed (or will contribute) to the A27 mitigation under the 2016 SPD.

4.12 At the time that the Proposed Submission Plan was published, the number of planned new uncommitted dwellings located in the south of the District is 3,551. This number will be updated before this SPD is adopted to ensure it represents an accurate estimate of the total number of dwellings from which this SPD will be able to secure the targeted level of funding.

The impact of development on the A27 Chichester Bypass

4.13 The A27 Chichester Bypass is a key strategic transport corridor for the south of Chichester District. It is frequently used (or crossed over) by all motorists living in this area and it provides the key route to the east and the west from Chichester. The modelling work undertaken to support the new Local Plan has shown that the impact on the A27 of those living within the District represents only a portion of the overall impact, with 'through traffic' making up the remainder. Nevertheless, the impact from Chichester's residents is significant and will be exacerbated by the development coming forward now and over the future Local Plan Period.

4.14 The 2016 SPD was adopted soon after the adoption of the current Local Plan. It was therefore possible to assess the proportionate impact of the various developments allocated in the Local Plan by reference to the anticipated number of vehicle trips that would be generated in each case. This was then used to derive a 'contribution per dwelling' based on the trip generation modelling as a proxy for the likely impact on the A27 Bypass of each site allocation.

4.15 That approach is not possible to take forward in this SPD. One reason for this is that many of the site allocations in the adopted Local Plan have secured planning permission (or a resolution to grant) meaning that the majority of the new development coming forward now is from unallocated sites or from sites that were allocated within neighbourhood plans. Neither of these were included in the modelling that supported the 2016 SPD. A second reason is because much of the development coming forward now is from windfall and speculative schemes, the Council has no certainty of the level of funding that could be secured through planning contributions if these were assessed by reference to anticipated vehicle trip generation. Therefore, this SPD will assess the 'per dwelling' contributions based on an equal level of impact for all development sites across the south of Chichester District.

Viability testing

4.16 Based on a known target level of infrastructure funding to secure and an overall level of uncommitted new homes that can come forward within 'infrastructure constrained approach' it is possible to calculate the per-dwelling contribution level that would secure the necessary funding. Based on the details set out above this would equate to £27,068,915 / 3551 dwellings = £7,623 per dwelling.

4.17 Based on this, the Council tested a figure of up to £8,000 per dwelling as part of the Local Plan Viability Assessment – Stage 2 (DSP, January 2023). This testing took account of all of the proposed planning contributions, including those to be secured through Planning Obligations, CIL and also through planning conditions (such as dwelling space standards).

4.18 The outcome of the viability testing was that the majority of development scenarios across the south of the District were found to be sufficiently viable at an A27 mitigation contribution level of £8,000 per dwelling, with significant viability 'headroom' for most development scenarios, particularly those on greenfield sites. However, at this level of contribution, the scenarios comprising solely of flats on brownfield sites were not viable. This was also true of the scenarios comprising an 'Extra Care' scheme and older persons sheltered housing.

Calculation of planning contributions

4.19 The Council acknowledges the outcomes of the viability testing and also recognises that dwellings do not all have the same impact on the A27. Smaller dwellings generally have fewer occupants who drive and own a car and therefore have a generally smaller impact than is the case with larger dwellings where the larger number of occupants would, on average, own and drive more cars. Therefore, varying the contribution by size of dwelling responds to the need to ensure that the contribution is proportionate to the development and would also respond to the outcomes of the viability testing since brownfield sites in urban areas tend to have a greater number of smaller (apartment) dwellings when compared to typical greenfield development at the urban edge or within rural areas which tends to have a larger number of family-sized houses.

4.20 In light of the reasons above, the A27 mitigation contributions will be scaled by size of dwelling, so that larger homes will pay more than the 'flat rate' and smaller homes would pay less.

4.21 In order to determine an appropriate scale, it is necessary to ensure that the overall funding target (£27 million) remains achievable with a scaled approach, when considered against the range of dwelling sizes that may come forward. It is not possible to predict with certainty what the future size of dwellings will be, but it is possible to look to the past at the average dwelling size that has been completed during the past 10 years. Doing so shows that in the past decade, 46.5% of all dwellings completed in the south of the District were 'smaller homes' (1-2 bedrooms) and 53.5% were 'larger homes' (3+ bedrooms). This supports the mid-point of the scale being placed at between 2 and 3 bedrooms (in other words at 2.5 bedrooms).

4.22 Some guidance on the future mix of dwellings within the District can also be gained from the latest HEDNA (Housing and Economic Development Needs Assessment) which was completed in April 2022 and is available on the Council's website. The 'suggested housing mix' within the HEDNA has been used to look at the possible size of dwellings coming forward in future years, applying the Council's target for affordable housing as set out within the Proposed Submission Plan. This indicates that, in coming Plan Period, 49.5% of all dwellings in the District could be 'smaller homes' (1-2 bedrooms) and 50.5% could be 'larger homes' (3+ bedrooms). In summary, the HEDNA suggested mix would entail a 3% increase in smaller homes and the equivalent decrease in larger homes.

4.23 Using the approach set out above, a contribution rate of £3,049.16 per bedroom has been established (£7,623 divided by 2.5). This would then provide the following contribution scale (rounded to the nearest whole £):

• 1-bed = £3,049
• 2-bed = £6,098
• 3-bed = £9,147
• 4+ bed = £12,197

4.24 When applied to the anticipated uncommitted dwellings (3,551) within the overall 'cap', the total contributions secured would be as set out in the table below. This shows the position both for a future housing mix that reflects the delivery experienced in the past decade and also a future mix that reflects the recommendations set out in the 2022 HEDNA:

4.25 The table above shows that under each of the two future housing mix scenarios, the proposed contributions set out above would be sufficient to secure the target level of funding required to deliver the 'reduced infrastructure package' comprising improvements to both Fishbourne and Bognor junctions.

4.26 Due to the uncertainty on the precise housing mix that will come forward, the Council will monitor the level of funding being secured and if, due to the actual mix coming forward, the funding falls below the required target, this could trigger a review of this SPD.

Development to which the contributions will and will not apply

4.27 The A27 mitigation contributions will apply to any net increase in new dwellings coming forward in the area to the south of the National Park. The contribution will be sought from all new dwellings including from affordable homes, retirement homes (such as sheltered housing), from self or custom-build homes and from caravans permitted for permanent occupation as a dwelling.

4.28 There are some cases where paying the A27 mitigation contribution would not be sought. The list below is not exhaustive however, and where applicants are in doubt, they are advised to ask about this during pre-application engagement with the Council.

Care homes / Extra Care facilities (Use Class C2)

4.29 Older and disabled persons care homes (including Extra Care homes) are generally for people who do not own or drive cars and so tend to have a very small or negligible impact on the A27 Chichester Bypass. For private care homes or Extra Care homes where parking spaces are provided for residents (beyond the normal level of visitor parking), the Council will consider applying the A27 mitigation contribution.

Purpose-build student accommodation

4.30 As with care homes, purpose-built student accommodation does not tend to provide parking spaces for the occupants or allow for the use of cars by students. These types of accommodation tend to be located within urban areas with good access to sustainable modes of travel. For student accommodation schemes where parking spaces are provided for occupants (beyond an appropriate level of visitor parking), the Council will consider applying the A27 mitigation contribution.

Gypsy and Traveller pitches

4.31 The Local Plan Transport Assessment (January 2023) advises that development comprising Gypsy and Traveller pitches has a negligible impact on the A27 Chichester Bypass. In addition, there is no viability evidence to support applying a financial contribution to the delivery of pitches.

Holiday lets

4.32 For accommodation (whether a building or caravan) where the planning permission is for short-term holiday lets, it would not be appropriate to apply the contribution as this could result in double-counting the impact on the A27, to the extent that those using the lets may live within the south of the District. In addition, there is no viability evidence to support applying a financial contribution to the delivery of holiday accommodation.