Economic Impacts of Tall Buildings and Transport Accessibility
T Kornblatt, K Arter, P Buchanan, J Siraut, Colin Buchanan, UK
The economic impacts of tall buildings are assessed and found to be particularly sensitive to transport access. External benefits from agglomeration are estimated in scenarios adding tall buildings near and not near transport nodes.
Tall commercial buildings (roughly buildings 30 storeys or more) have become an increasingly controversial topic in planning and land use development circles. Thus far, the debate has focussed largely on aesthetic impacts of tall buildings. This research suggests that tall buildings also create external economic benefits, in the form of agglomeration impacts, when placed by key transport nodes. This research allows economic impacts of tall buildings to be effectively considered and evidences the importance of locating tall buildings with careful consideration of transport provision and impacts.
Tall buildings provide an opportunity for increased density in key districts in urban areas, particularly around transport nodes where available land is often scarce. In these areas ?building up? may be the only way to achieve increased densities.
These increased densities have economic and environmental impacts. Our research is testing those impacts, finding the key driver to be agglomeration benefits, and, furthermore, finding that locating a tall building near major transport nodes (with spare capacity) is a key determinant in the agglomeration benefit that a tall building can provide.
We are undertaking a case study in London, comparing output and productivity in three scenarios in 2026:
1. A ?base? scenario, depicting expected employment growth, density, and resulting output as specified by London Plan projections of scale and distribution of employment in 2026.
2. A ?tall buildings at transport nodes? scenario, where tall buildings accommodating 20,000 employees are added at four key transport nodes in London, expected to have available capacity with the opening of Crossrail. Total employment in London in 2026 stays the same as in the base scenario; ?shifted? employees moving to the four tall buildings nodes are distributed evenly across the Central London boroughs containing the tall buildings.
3. A ?tall buildings not at nodes? scenario, where tall buildings of the same scale are added in four areas not at key transport nodes. Again, total employment in London in 2026 remains the same as the base, with an even reduction of employees across the relevant boroughs in London.
These scenarios are modelled at small scale geographies (Railplan zones ? there are about 1,100 of these in London), where employment and output per zone is calculated in the base case. Then, the resulting changes in effective density (taking account of employment density and job accessibility) per zone are calculated with the tall building scenarios. Agglomeration elasticities (from work by Graham, 2006) are applied to estimate the change in output per zone based on the change in effective density.
Total output for London can then be summed for each scenario, and, as total employment is the same for all scenarios, productivity can be calculated showing the impact of the change in density allowed by tall buildings.
Early results suggest that the tall buildings near transport nodes scenario creates significant external agglomeration benefits, while adding tall buildings at non-transport nodes creates external agglomeration disbenefits.
Further efforts will:
1. Estimate impacts over a 35-year lifespan.
2. Contextualise any external impacts by comparing to the estimated costs of tall buildings.
3. Summarise sustainability potential for tall buildings in an economic context, particularly related to efficient land use and potential for reduced carbon emissions through reduced private vehicle usage.
We expect this research will inform:
1. Planning decisions/policy on tall buildings ? adding credible economic impacts for consideration and allowing a more complete assessment of the trade-offs of tall buildings
2. Location decisions for tall buildings ? strengthening the case for careful consideration of transport provision and location of tall buildings.
3. Mixed use development ? potential for a suggested trade-off of agglomeration benefits where employment density is sacrificed for other uses in key urban zones
Association for European Transport