New road construction

Policy contribution

Contribution to objectives

Objective	Scale of contribution	Comment
	/	Road building can induce traffic and undermine benefits from congestion reduction.
	/	Some new roads may remove some traffic from residential areas and so improve safety, air quality and noise. New roads, particularly if they induce traffic can worsen pollution, safety, severance and noise.
	/	See above. Increased traffic can increase carbon emissions and other pollution. Land use for roads can damage built and natural environment, impose mortality on wildlife if habitats are severed, and construction has associated environmental costs.
	/	See liveable streets above. New roads risk exacerbating inequalities in safety and accessibility faced by vulnerable road users.
	/	See liveable streets above
	/	The relationship between transport and economic development is uncertain. Road building can induce traffic and undermine benefits from congestion reduction; social and environmental impacts of new roads (including severance, poor health from pollution, carbon emissions and safety reduction) have associated economic costs further reducing benefits.
		High capital expenditure is required. Benefits can be uncertain – see sections above.

	= Weakest possible positive contribution,		= strongest possible positive contribution
	= Weakest possible negative contribution		= strongest possible negative contribution

= No contribution

Contribution to problems

Contribution to alleviation of key problems

Problem	Scale of contribution	Comment
Congestion		Road building can induce traffic and undermine benefits from congestion reduction.
Community impacts	/	Some new roads may remove some traffic from residential areas and so improve safety, air quality and noise. New roads, particularly if they induce traffic can worsen pollution, safety, severance and noise.
Environmental damage		Increased traffic can increase carbon emissions and other pollution. Land use for roads can damage built and natural environment, impose mortality on wildlife if habitats are severed, and construction has associated environmental costs.
Poor accessibility	/	Some new roads might improve accessibility, either by unlocking areas of land or shifting traffic from congested areas. However new roads can increase severance for vulnerable road users and residents.
Social and geographical disadvantage	/	Some new roads may remove some traffic from residential areas and so improve safety, air quality and noise. New roads, particularly if they induce traffic can worsen pollution, safety, severance and noise.
Accidents	/	See above
Economic growth	/	The relationship between transport and economic development is uncertain. Road building can induce traffic and undermine benefits from congestion reduction; social and environmental impacts of new roads (including severance, poor health from pollution, carbon emissions and safety reduction) have associated economic costs further reducing benefits.

	= Weakest possible positive contribution,		= strongest possible positive contribution
	= Weakest possible negative contribution		= strongest possible negative contribution

= No contribution

Appropriate contexts

It is difficult to assess appropriate context. While benefits and harms of road building are very contested in general, it also seems that any case for new road building will depend on specific circumstances, such as ability to remove traffic from a residential or sensitive area, or ability to unlock appropriate land for development.

Appropriate area-types

Area type	Suitability
City centre	/
Dense inner suburb	/
Medium density outer suburb	/
Less dense outer suburb	/
District centre	/
Corridor	/
Small town	/
Tourist town	/

= Least suitable area type

= Most suitable area type

Adverse side effects

As described above, there are multiple adverse impacts of new road construction including:

Failure to reduce congestion: if traffic volumes are expected to rise over time (Eddington 2006). The risk can be exacerbated if the increased road space acts to induce additional traffic (e.g. Cervero 2003).
Land use for road construction can be at the expense of homes, businesses, and natural habitat.
Resources used for road construction have environmental costs (e.g. Seo and Kim 2013).
If new roads allow for accommodation of higher overall volumes of motor traffic, this will increase carbon emissions.
New roads can expose adjacent communities to increased transport related pollution, and associated increases in mortality from cardiovascular illness and cancer (WHO 2013; Loomis et al. 2013). However it should be noted that construction of bypasses can shift some transport related pollution from residential areas.
Severance: depending on their location and design, roads can act as a barrier to for people in communities who need to cross the road to access employment, education, services, and everyday activities (SEU 2003). Roads can also act as a barrier for wildlife, sometimes creating pressure on viability of animal population, dissecting habitat and causing substantial mortality (Marcantonio et al. 2013).