Planning for Sustainable Travel

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CASE STUDY: DIDCOT, OXFORDSHIRE

Map of Didcot, Oxfordshire

Background

This case study examines one of 29 growth points across England – Didcot, Oxfordshire. Didcot is located 15 km south of Oxford.

The selected development at Didcot comprises a mixed urban extension together with associated infrastructure. The 180 hectare site known as Great Western Park (GWP) is located around the western edge of the existing built-up area, about a mile from the grade separated interchange of the A4130 with the dual carriageway A34. Most of the site (and Didcot itself) falls within South Oxfordshire District, the remainder within the Vale of White Horse district.

In July 2008, South Oxfordshire and the Vale of White Horse District Councils gave permission for the development at GWP. The first planning application for this project was made in 2002.

Towards Sustainable Travel

Achieving sustainable travel in Oxfordshire, and the Great Western Park (GWP) development at Didcot in particular, would require a real ‘trend break’ relative to current travel patterns. While South Oxfordshire has an approximate UK-average proportion of journeys to work by car (62%), lengthy journeys to work (32% over 10km) and a rate of traffic growth between 1997-2007 at the UK average (13%) contribute to high transport CO2 emissions at 3.4 tonnes per person. The current extent of car use in Didcot is more notable given that the town enjoys exceptionally good accessibility by rail, being on the high speed rail line between Swindon, Reading and London Paddington and with regular local services to Oxford.

This case study presents some positive elements of land use planning that may encourage sustainable travel at Didcot but also the potentially adverse outcomes of previous decisions concerning the location of new development in Oxfordshire.

Settlement Size

Larger settlements (over 25,000 population), especially larger contiguous urban areas like Liverpool and Manchester, tend to exhibit shorter travel distances and lower car mode share. In Oxfordshire however there has been, since 1974, an explicit planning policy of protecting a tightly-drawn Green Belt around Oxford City and diverting the bulk of new development to four smaller ‘country towns’, Didcot being one. This policy both utilised and strengthened the provision of employment and social infrastructure in these towns and was originally expected to result in their relative self-containment. Since then, the combination of high house prices in Oxford City and the outer urban area, the rapid growth of car ownership and the rebuilding of the A34 to near motorway standard has transformed the possibilities for home and work location and commuting and wider travel patterns.

In responding to this and to increasing problems of housing affordability within Oxford, the recent South East Plan proposes a notable departure from past policy in the county. This takes the form of a major urban extension to the south-east of the City together with an associated local review of the Green Belt boundary. However this change continues to be contested by South Oxfordshire District in whose administrative area the extension falls. Because of increases in the projected housing requirement for Oxfordshire as a whole this has not reduced the additional housing planned elsewhere. Didcot also applied successfully for designation as one of the country’s ‘growth points’ to achieve accelerated housing provision.

Didcot, with a population of 25,000, has the potential for some self-containment especially if a slightly broader view is taken to include the major and expanding employment areas at nearby Milton Park and Harwell adjacent to the A34. However the presence of the trunk road and the high speed rail line inevitably render the town attractive for longer distance out-commuting.

Movement Network Strategy for Great Western Park, Didcot

Movement Network Strategy for Great Western Park, Didcot

(Great Western Park Exhibition, South Oxfordshire District Council)

Development Site Location

A study of potential ‘directions of growth’ for Didcot resulted in the decision to expand the town to the west rather than the north. Over the years there had been much debate between the various stakeholders and interest groups as to the location of growth around Didcot (North-East or West or both). The GWP location was selected in part because of its location between Didcot and the A34, thereby eliminating the need for generated traffic to pass through the town and avoiding potential ‘rat-running’ traffic on rural roads north of the town towards Oxford.

Proximity to major employment areas was also cited as a factor in the decision to locate development at GWP. Good public transport links will be necessary to support sustainable travel within the local area. For example, there are provisions in the draft s.106 agreement for significant developer contributions towards off-site transport infrastructure and maintenance, including bus priority measures, a public transport interchange and a £3.8m contribution towards bus subsidies. There is also funding for the cost of the local authorities to develop and monitor the green travel plan to be prepared for GWP.

However, the extent to which these measures will actually impact on the amount of travel by car is doubtful given that it is only in inner Oxford (the destination of a very small proportion of trips) that significant policies of demand management apply. This is an issue replicated around the UK. The possible deterrent effect on car use of congestion in accessing the A34 has also been removed through substantial works undertaken to increase its capacity in association with development at GWP.

Given the strategic decision to continue to expand Didcot (a ‘lesser evil’ in transport terms compared with more scattered development elsewhere in the two Districts) the decision on development location illustrates the interplay between the objectives of minimising traffic problems (a conventional Highways Agency objective) and minimising car travel. Ensuring that the development has easy access to the A34 minimises traffic-related problems on the local road network, yet implicitly encourages longer distance car travel, and adds to the overall volume of car use. Although immediate congestion problems at the Milton Park interchange are addressed by specific works, the general problem of additional ‘local’ traffic worsening conditions on the length of the trunk road through Central Oxfordshire has been exacerbated.

Mix of Uses

Allowing a greater mix of uses within a neighbourhood is likely to reduce travel distances as people link trips in order to access multiple destinations within a single trip. The GWP urban extension in Didcot will include a new primary school, a secondary school, open spaces, local shops and services, play areas, two community centres and a health centre in addition to 3,300 new homes (30% of which will be affordable), thus has an effective mix and range of facilities.

The actual realised ‘mixed use’ nature of the development (i.e. proportion of retail provided) depends largely on financial viability. Hence, while developers can be ‘requested’ to allocate areas for retail and other non-housing uses, the actual provision will depend on whether this is deemed to be profitable and deliverable. The financial viability of retail uses is generally improved by higher densities, with locations accessible by multiple modes. Again this is a common problem in masterplanning – achieving the vision is often difficult in practice.

The proposed development layout at GWP, below, shows the concentration of development and facilities in relation to the proposed bus route spine running through the site.

Enabling Conditions

Land use/transport planning outcomes are strongly influenced by the institutional context in which they develop. Didcot provides a number of lessons for practice elsewhere.

Cross-Authority Working

Practitioners involved in Didcot felt that the complexity of the site selection and development planning process was aggravated by the site being divided between two local planning authority areas, plus a separate highway authority. Changing personnel and companies representing the developer in planning negotiations were added difficulties

Funding Mechanisms

The Didcot planning application took four years to negotiate (with the applicant making and then deferring an appeal at three stages), plus a further two years to negotiate the main terms of the s.106 agreement. This is despite the planning authorities being under considerable pressure from the Government to deliver additional housing numbers. A buoyant development market [at the time] did enable relatively large payments to be negotiated towards both highway and public transport improvements, as well as securing funding for a range of non-transport facilities.

Significantly, there was, in effect, an ‘alliance of interest’ between the District and County Councils to use the opportunity presented by the GWP development to safeguard and improve local traffic conditions, but in doing so to facilitate large increases in the future overall volume of car travel.