Land use and housing
Future growth would be mostly contained within Christchurch (85% of population growth - 44,310 extra people by 2021) and the larger towns of Rangiora, Pegasus Bay and Rolleston. Development would include both re-development of existing housing (for example, replacing older homes on larger sections with townhouses and apartments) and developing new subdivisions generally adjacent to existing areas. This would require the least amount of land currently being used for farming, to become residential. Around 60% of new housing would be urban renewal, and only 40% would be for new subdivisions, as further restrictions would be placed upon extensive development beyond the existing edge of Christchurch and towns. A green belt of open space and parkland would be established to prevent urban areas, Christchurch , Rangiora, Kaiapoi and Rolleston, spreading into farmland or each other.
Section sizes within the Central City and inner suburbs of Christchurch would be smaller as redevelopment increased and there would be more two to four storey dwellings. Mixed developments of commercial space on lower floors and residential on upper floors would occur. Redevelopment in suburbs such as Spreydon, Linwood, St Albans and Riccarton would increase as multi-storey townhouses, apartments and flats replace older villas and bungalows. There would be more intense development in some locations, in the districts such as Rangiora and Rolleston.
By redeveloping existing suburbs, it should be possible to reuse the existing infrastructure, upgrading where necessary. This is considerably cheaper than the cost of developing new infrastructure for new subdivisions. Infrastructure upgrades of water, sewerage and power would still be required and might cost the community as much as $260 million by 2041 and $430 million by 2041. People not wanting to live in more densely populated areas would still be able to live in homes on larger sections in the outer suburbs, or in the surrounding towns. Though there would be choices of housing type in existing suburbs as more redevelopment takes place, it might not be affordable for all income groups.
The cost of residential development will vary between locations and depend on the quality of the development but land costs for residential development are likely to be higher per unit/lot under this option (because of reduced land being available), which may push up house prices. Affordable housing programmes may need to be developed to ensure all income groups have access to good quality housing.
Transport
Concentrating development within and around existing urban areas will make some roads more congested (50% increase in congestion by 2021, 190% by 2041) increasing travel times (commute takes 21% longer by 2021, 45% longer by 2041). For example, a trip to work that takes 30 minutes today would take 36 minutes in 2021 and 44 minutes in 2041.
Some road widening of key arterials may be inevitable and could be costly. With growth of towns such as Rolleston and Rangiora, the roads connecting these towns to Christchurch will also need upgrading to avoid the predicted growth in congestion (road infrastructure improvements and maintenance costs $1.4 billion by 2021 and $1.9 billion by 2041/500,000 population). By 2041 we would be spending over $.5 billion each year on motoring (fuel and the cost of crashes), in addition to the $1.9 billion spent on roading.
Some people may end up living closer to their work places making walking, cycling and public transport practical alternatives to driving their cars. Much greater investment in public transport would occur, making Metro services more attractive.
Community identity and facilities
Redevelopment of existing urban areas will change the character of neighbourhoods. Planning and coordinating redevelopment will ensure that many of the existing community social structures and facilities are retained in the transition. Concentrating development within existing urban areas increases the potential for new residents to maintain and enhance community identity through joining existing social, cultural and sporting groups. This should ensure the survival of existing social networks as well as community amenities such as swimming pools, libraries and schools. Without additional residents local communities might not be able to retain these amenities. The increased number of families with school aged children moving into inner suburbs could balance the decline in overall numbers of school aged children, making the best use of existing facilities.
Existing shopping and retail centres are likely to expand and become more commercially viable, offering greater employment opportunities and a wider range of products and services to their local communities .
Large numbers of new residents moving into existing communities could also change the character of communities and the services required. For example, more quality public space would be required to meet the demand from people living in higher density developments with less private outdoor and recreational space. To ensure redevelopment enhances the character of existing communities, councils will need to set clear urban design guidelines and play a leading role, such as facilitating redevelopment where appropriate.
Natural environment
By limiting growth to within and around the existing urban areas, it would be possible to create green zones or parks and open spaces around each urban area. Regional parks will provide habitats for native plants, birds, insects and animals, and provide for recreational activities from team sports to individual pursuits such as walking and hiking. Increasing the number of dwellings in urban areas would increase demand and use of existing local parks.
Focusing redevelopment on older established suburbs would result in older homes, built without insulation and heated with open fires, being renovated to become well-insulated homes heated with gas or electricity. As a result air quality should improve by reducing the overall level of wintertime pollution from home heating.
Vehicle emissions increase 15% by 2021 and 49% by 2041 (carbon monoxide produced will be 140 tonnes/day in 2021 and 180 tonnes/day by 2041). With more people living closer to established amenities such as schools and shops it would be easier and more attractive for people to walk, cycle or use public transport instead of driving their cars.
By reducing overall section sizes and the area of gardens and lawns requiring watering, the volume of water used by households would be reduced. Overall water consumption would reach 2,830 litres per second in 2041, a 35% increase from 2001 consumption.
Responding to natural hazards may improve by concentrating development closer to emergency services such as police, fire and ambulances. Concentrating development in Christchurch's Central City and inner suburbs, however, may present increased risks from some hazards. Central Christchurch is at risk of flooding from the Waimakariri River. The low-lying, soft sandy soils of Christchurch's eastern and inner suburbs are prone to liquefaction during earthquakes and coastal areas of Christchurch and surrounding communities are at risk from tsunami.
By restricting development to within and around existing urban areas, farmland can continue to be used for primary production, and outstanding natural landscapes, such as the Port Hills can be preserved.