Cost benefit analysis of peri-urban land use policy - Plurel

Scenarios for the GDA
Within the framework of Strategic Environment Assessment for the GDA, three scenarios are subject
to evaluation including: 1) Business-as-usual scenario 2) Finger expansion scenario 3) Consolidation
scenario.
Scenario 1: Business-As-Usual
In this scenario, current trends in land zoning, land development and transportation are continuing
with a limited implementation of Transport 21 project (see Figure 3) and planning/policy decisions
stated in the RPGs (2004). This implies that proposed growth nodes of the RPGs are not supported
by the necessary public transportation networks and/or land zoning decisions and implementations.
In the Regional plan, the primary and the secondary growth nodes are attached the role of selfcontainment,
and will be separated from each other by greenbelts surrounding them. Since there is
limited integrated transportation/land-use planning supporting the development of the primary
growth nodes; this situation acts as an obstacle in this scenario for the development of the new
growth centres. Consequently, new development spreads to the outskirts of the existing development
where there is abundant of greenfield land at lower prices. The final result is dispersed type of
settlements around the Dublin Region with high employment dependency on the core of the Dublin
Area (see Figure 4).
Increase in car dependency associated with dispersed development and the resultant increase in
traffic congestion are some problems seem to have significant impacts in the GDA. Low density and
private car dependent developments -as the sprawl patterns in this scenario-are less accessible,
requiring more travel to reach urban activities, and reducing transportation options i.e. cycling,
pedestrian and public transit access. The result is the increase in transportation costs-both user costs
and external costs. Furthermore, the characteristic of dispersed development in this scenario is seen
to be unsustainable considering that it necessitates providing infrastructure and services to the low
density population on urban periphery reflecting the main cost of infrastructure provision on the
society as a whole. It also causes loss in productive agricultural land and reduction of landscape
amenity, and related to indirect externalities such as: negative effects on air/water quality, increased
accessibility costs, and unwanted social equity costs.
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