New Road Construction

This measure was provided by INSTITUTE FOR TRANSPORT STUDIES (ITS) in 2014 under the CH4LLENGE project, financed by the European Commission.


Road construction has apparently simple aims of providing access to areas previously inaccessible by motor vehicle, reducing traffic volume in one area by moving it to another, or of increasing capacity.  Yet each of these aims can result from many, complex motivations.  Road construction is prominently promoted as a facilitator of economic growth, however evidence to support a causal relationship between new roads and economic benefit is very contested. There is some evidence that road building induces increases in motor traffic and this is associated with problems of poor air quality, higher carbon emissions, reduced safety, severance for vulnerable road users and congestion. Conversely, there is evidence that new roads which bypass sensitive areas can improve safety and the environment; however, increases in traffic can offset these benefits.

Introduction and Terminology

Road construction or road building covers a range from creation of entirely new roads reaching places where no road access previously existed, through bypasses to relieve sensitive areas, to intensification of the road network, and widening of existing roads in order to increase capacity. Road construction is not here taken to mean re-configuration of existing roads (for instance, to straighten bends) since this can involve very different purposes and problems. Construction of cycle routes and pedestrian areas are covered elsewhere. The following description will consider roads intended for use by motor vehicles as well (often) as other users.

Description

Road construction can take ostensibly straightforward aims of providing access to areas previously inaccessible by motor vehicle, reducing traffic volume in one area by moving it to another, or of increasing capacity.  Yet each of these aims can result from many, complex motivations.

Why introduce road construction?

Road construction is perhaps most prominently promoted as a means of bringing economic benefits or encouraging economic development. The intention can be that economic benefits would flow from the road’s use in unlocking new areas of land for development, or by reducing distance travelled between places or by enabling time saving for road users by reducing congestion (see for instance, SACTRA 1999; Eddington 2006; Bulkwalter 2013).  However there is significant uncertainty and debate about the relationship between road construction and economic development, and about the way in which economic impacts are appropriately measured. 

  • An aim of supporting economic development by reducing congestion through increasing road space risks failure if traffic volumes are expected to rise over time (Eddington 2006).  The risk can be exacerbated ifthe increased road space acts to induce additional traffic (e.g.  Cervero 2003). This risk prompted the Eddington Study to argue that road construction would need to be carried out in conjunction with demand management, particularly road user charging, if any benefits in reducing congestion were to be realised.
  • Assessment of economic impacts of road construction should take account of impacts beyond those associated with time savings from reduction in congestion. External economic impacts (e.g. economic impacts of pollution, collisions) should be considered and this can outweigh economic impacts of time savings (SACTRA 1999, see also Stern 2007).
  • The association of economic benefit with time saving is contested (SACTRA 1999;Banister 2008).

Economic considerations might appear to dominate motivations for road construction, but they are not the alone. Some road construction is designed to remove traffic from areas where it is especially problematic, such as residential areas, town centres, historic sites. The intention can be to improve local air quality and noise pollution in areas of habitation; to improve safety; to reduce severance; or to enhance liveability. These benefits may need to be offset against travel time increases if bypasses involve significant diversions. Questions of whether such roads achieve their goals can depend on factors including design, whether there are increases in overall traffic which overwhelm reductions due to the diverted traffic, whether road construction is accompanied by complementary measures, such as road user charging, improvements to infrastructure for pedestrians and cyclists, other accident remedial measures (e.g. speed limits and traffic calming).      

Road construction brings a range of potential difficulties, from the construction itself and land taken for the road, to the impacts of traffic that comes to use the road:

  • Land use for road construction can be at the expense of homes, businesses, public space 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 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). 

Demand impacts

Responses and situations
Response Reduction in road traffic Expected in situations
/ If road construction increases efficiency by reducing peak journey times, some traffic might return the peak periods. 
/ If road construction takes traffic away from residential or other sensitive areas there might be some benefit. However these can be offset by induced increases in traffic. 
/ New roads might unlock development land. Bypasses might be associated with loss of trade as potential customers no longer drive through a town.  
New roads can induce traffic.
/ Bypasses might contribute to improving conditions for pedestrians and cyclists in the area bypassed. However increasing road capacity will be likely to prompt a shift to motor travel. 
Increasing road capacity will be unlikely to prompt a shift from motor travel. 
Road construction might contribute to urban sprawl and increase car dependency.
= Weakest possible response = Strongest possible positive response
= Weakest possible negative response = Strongest possible negative response
= No response

Short and long run demand responses

Demand responses
Response - 1st year 2-4 years 5 years 10+ years
Some traffic may return to peak periods in the short term / /
  If road construction takes traffic away from residential or other sensitive areas there might be some benefit. However these can be offset by induced increases in traffic.  / /
  Dis-benefits to bypassed areas might increase over time. / / / /
  If traffic expected to increase over time.
  If traffic expected to increase over time.
  Little longer term impact expected.
  Likely to be lagged response.
= Weakest possible response = Strongest possible positive response
= Weakest possible negative response = Strongest possible negative response
= No response

Supply impacts

Increased road space directly adds to supply and might act to induce additional motor traffic (e.g. Cervero 2003). There may be reduction in congestion, although the extent of this will depend on whether traffic increases either because of the road construction or for other reasons.  Bypasses which shift traffic from certain areas might contribute to supporting improved conditions for pedestrians and cyclists in those areas, but supply will still be increased unless the bypassed road is closed.  

Financing requirements

Road construction requires substantial capital investment either directly from taxation, or borrowed with interest from the private sector, or in cases such as toll roads, directly from the private sector with people paying to use the road. 

Expected impact on key policy objectives

Contribution to objectives

Objective

Scale of contribution

Comment

  / Road building may relieve congestion in the short term, but can induce traffic and undermine these benefits.
  / Some new roads may remove some traffic from residential areas and so improve safety and the quality of local streets.  especially for those living along or near the route, but also if induced traffic impacts on other parts of the road network.
  / 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. Conversely, bypasses can improve the environment on bypassed roads.
  New roads risk exacerbating inequalities in safety and accessibility faced by vulnerable road users. Conversely, bypasses can improve conditions if roads in deprived areas are bypassed.
  / New roads will typically be designed to a higher standard and hence be safer.  Bypasses can remove traffic from accident blackspots.  These effects may to some extent be offset by growth in traffic. If congestion is reduced on parts of the road network (including the new road), and speed increases accordingly then this will bring further risks especially to vulnerable road users.
  / The relationship between transport and economic development is uncertain. Roads which access new developments can support the economy. Those which add capacity may support the economy in the short term, but this can be offset by growth in traffic.  Bypasses may have an adverse effect on trade in bypassed areas.
  High capital expenditure is required.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Expected impact on problems

Contribution to alleviation of key problems

Problem

Scale of contribution

Comment

Congestion

Road building may relieve congestion in the short term, but can induce traffic and undermine these benefits.
Community impacts / Some new roads may remove some traffic from residential areas and so improve safety, air quality 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. Conversely, bypasses can improve the environment on bypassed roads.
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 / New roads will typically be designed to a higher standard and hence be safer.  Bypasses can remove traffic from accident blackspots.  These effects may to some extent be offset by growth in traffic. New roads, particularly if they induce traffic on parts of the road network, can be detrimental to safety. If congestion is reduced on parts of the road network (including the new road), and speed increases accordingly then this will bring further risks to cyclists.
Poor economic growth / The relationship between transport and economic development is uncertain.  Roads which access new developments can support the economy.  Those which add capacity may support the economy in the short term, but this can be offset by growth in traffic.  Bypasses may have an adverse effect on trade in bypassed areas.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

Expected winners and losers

Winners and losers

Group

Winners/Losers

Comment

Large scale freight and commercial traffic

/ Will benefit as long as increases in traffic do not offset reductions in congestion. May benefit from unlocking areas for development.

Small businesses

/ Will benefit if increases in traffic do not offset reductions in  congestion. May benefit from unlocking areas for development. May lose passing trade if traffic bypasses business areas.

High income car-users

/ Will benefit if increases in traffic do not offset reductions in congestion.
Low income car users with poor access to public transport / Will benefit if increases in traffic do not offset reductions in congestion.
All existing public transport users New roads might encourage shift to motor traffic and reduce viability of some public transport (see Highways Agency 2009).
People living adjacent to the area targeted / Increased traffic can create problems if it goes through adjacent areas (see e.g. Highways Agency 2009b). Areas might gain some benefits in air quality, safety and accessibility if traffic is removed from an area. However business may also lose passing trade.
Cyclists including children / Some new roads may remove some traffic from residential areas and so improve safety for vulnerable road users. New roads, particularly if they induce traffic on parts of the road network, can be detrimental to safety and accessibility. If congestion is reduced on parts of the road network (including the new road), and speed increases accordingly then this will bring further risks to cyclists
People at higher risk of health problems exacerbated by poor air quality / Some new roads may remove some traffic from residential areas and so improve air quality. New roads, particularly if they induce traffic can worsen pollution especially for those who live or work in the vincinty of increased traffic.
People making high value, important journeys Will benefit if increases in traffic do not offset reductions in congestion.
The average car user Will benefit if increases in traffic do not offset reductions in congestion.
= Weakest possible benefit = Strongest possible positive benefit
= Weakest possible negative benefit = Strongest possible negative benefit
= Neither wins nor loses

Barriers to implementation

Scale of barriers
Barrier Scale Comment
Legal Governments often have powers to compulorsarily purchase land for road building. However there can be a range of legal objections, including formal inquiries, and legal objections that new roads will lead to breaches of legally binding air quality standards. 
Finance Road building is expensive, however authorities can be willing to provide funding mechanisms for new roads.
Governance Roads may go through or impact on several local authorities and agreement will be required in this case. People opposed to new roads will use requirements for consultation to make their case to stop road building.
Political acceptability This depends on politics at a given time. In many countries, road building has gone through periods of having greater or less political support.
Public and stakeholder acceptability / New roads often have supporters who perceive benefits of faster travel times, reduced congestion, and access to new areas for development. Road building often faces strong opposition on grounds of environmental concern relating to carbon emissions, pollution and loss of land and threats to natural habitat, health concerns, including safety and poor air quality, accessibility, and loss of homes or businesses on the line of a new road. 
Technical feasibility With some exceptions, e.g. geology or habitat not supporting infrastructure.
= Minimal barrier = Most significant barrier

M60 and M62 all lane running

In attempts to ease congestion, the (English) Highways Agency* had been considering a range of measures for increasing capacity on parts of the M60 and M62 around heavily populated areas in north-west England .  In a consultation document they launched in November 2013, the Highways Agency described how they had considered all lane running – that is using the hard shoulder.
“We looked extensively at the option to provide all-lane running on the M60 section between junctions 8 and 18. However, our environmental assessment concluded that creating this improvement would result in an increase in traffic using the motorway which would then have a detrimental affect on air quality.” (Highways Agency, 2013, p. 10)

The Highways Agency noted that UK and European environmental standards meant that the hard shoulder running was not an option that could be considered. Some NGOs, Campaign for Better Transport and Client Earth linked this decision to a Supreme Court decision in May 2013 which  ‘declared that the Government is failing in its legal duty to protect people from the harmful effects of air pollution’ (Client Earth, 2013).

*The Highways Agency is an ‘Exec­u­tive Agency of the Depart­ment for Trans­port’ responsible for the strate­gic road net­work in Eng­land’ http://www.highways.gov.uk/about-us/)

A27 Polegate Bypass and A22 Golden Jubilee Way

In 2002 in south east England, the A27 Polegate Bypass and A22 Golden Jubilee Way were opened. Both were new roads, both dual carriageway and together they were 6.5km.  The Highways Agency (for England) conducted evaluations of such schemes one year and five years after the schemes opened (Highways Agency 2009a). According to the 5 year study, the scheme overspent by 25% (costing £19.5m at 1988 prices) and this overspend was attributed in large part to increases in land prices. The study maintains that despite this, the scheme could be considered to be value for money which journey time reductions savings being greater than forecast (Highways Agency 2009a, iv, and chapter 9).

The study indicates that the schemes are associated with an increase in traffic substantially above that which would be expected otherwise on the basis of contemporary forecasting techniques. The study notes that traffic forecasts estimated an increase in traffic in Great Britain of 8.6% between2002 and 2007, although in the area in which the schemes were constructed (Eastbourne) the estimates were for a 6.5% increase over the same period. The study’s authors note that these estimates for Great Britain as a whole are slightly higher than observed increases. In this context, they also note that traffic along a corridor which pre-2002 contained two routes, and post-2002 also contained the new scheme, increased by 32% between 2002-2007 (Highways Agency 2009a, 5.13).

It was found that ‘Traffic flows on the B2247 through Polegate are 49% lower than pre-opening levels. However, there has been a 7% increase since the scheme opened’ However ‘[o]bserved flows in 2007 were 27% higher than the low growth and 10% higher than the high growth forecast.’ Nevertheless ‘[j]ourney times through Polegate on the B2247 have reduced slightly since the scheme opened’ (Highways Agency 2009a, iv). Further, the study reports ‘[t]here has been a slight shift of 2% from public transport… to car. This change could be seen as the improved highway infrastructure encouraging more residents to use their cars’ (Highways Agency 2009a, s12.6).

A number of dis-benefits were greater than expected as following the scheme, traffic in the town (Polegate) was higher than forecast. So [n]oise levels in Polegate are slightly worse than predicted’ and air quality in the town was assumed to be worse than expected although better than before the scheme opened (Highways Agency 2009a, v).  Further, ‘[c]arbon emissions in the opening year were slightly higher than the AST forecast ((Highways Agency 2009a, v). However the number of collisions both in the town and on major routes in the area has declined.

Contribution to objectives
Objective Scale of contribution Comment
  /

Although journey times increased A27 Polegate Bypass and A22 Golden Jubilee Way apparently prompted increasing traffic above levels that were expected otherwise, and above national  increases in the same period.

  / There were some benefits in the bypassed town, although not as great as expected due to higher traffic levels remaining in the town. Since it seems that the scheme led to higher traffic than otherwise expected, there may be dis-benefits to liveable streets elsewhere.
  /

The A27 Polegate Bypass and A22 Golden Jubilee Way schemes led to higher carbon emission than expected.

The case of the withdrawn idea of all land running indicates the problems of poor local air quality associated with increasing road capacity.
  / There were some benefits due to reduced severance in the bypassed town, although not as great as expected due to higher traffic levels remaining in the town (Highways Agency 2009a).  The slight shift to car use and away from public transport might have influence on viability of public transport routes. Increased traffic overall might contribute to longer term car dependency and exclusion of those without a car.
  There was reduction in serious collisions after the A27 Polegate Bypass and A22 Golden Jubilee Way opened.
  No evidence.
  The A27 Polegate Bypass and A22 Golden Jubilee Way scheme overspent by 25%.
= Weakest possible positive contribution = Strongest possible positive contribution
= Weakest possible negative contribution = Strongest possible negative contribution
= No contribution

 

Expected contribution to objectives

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.
  / 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.
  / 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. New roads risk exacerbating inequalities in safety and accessibility faced by vulnerable road users.
  / 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.
  / 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 /

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.

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). 

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