5 Potential impacts of road traffic
5.1 Effect of onshore oil and gas development on traffic
Studies of UOG development in Scotland, the UK as a whole and elsewhere consistently find that the road traffic impacts are one of the aspects of greatest concern both to the general public and professional analysts. The Independent Expert Scientific Report (2014) commented:  " It appears that for communities near unconventional oil and gas development sites, the main health impact "stressors" ( i.e. areas of perceived concern, even if unproven) are "air pollutants, ground and surface water contamination, truck traffic and noise pollution, accidents and malfunctions and psychosocial stress associated with community change…" This report concluded that " Social impacts documented from shale gas and CBM developments in the US and Australia have included … increased truck traffic." Traffic impacts were also highlighted in the preceding study carried out by the Tyndall Centre, and in the environmental risk assessment studies carried out by Ricardo for the European Commission  and Chesapeake Climate Action Network. 
These impacts arise principally from increases in heavy goods vehicle movements on potentially unsuitable roads. These movements would take place over a relatively limited period for an individual well, but may occur over a much longer period for development of a multi-well pad, and in particular in situations where a shale gas field is being developed. This pattern of potential effects of development on road traffic is comparable to the potential traffic effects of windfarm development, a scenario which is familiar in Scotland.
5.2 Community risks and impacts of traffic
Scottish National Indicators are set to enable progress towards the achievement of National Outcomes to be tracked. The following indicators are potentially relevant to this study:
- Reduce traffic congestion
- Reduce deaths on Scotland's roads
- Improve access to local greenspace
The indicators are useful in enabling traffic congestion, road safety and access to greenspace to be taken into account in decision-making processes.
The key starting point for identification and characterisation of environmental risks and potential impacts of traffic movements was the standard guidance for such studies in Scotland:
- Planning Advice Note 50: Controlling the environmental effects of surface mineral workings
- PAN 50 Annex C: Control of Traffic at Surface Mineral Workings
- Scottish Government "'Transport Assessment Guidance"
- Transport Scotland's economic appraisal guidance: "Development Planning and Management Transport Appraisal Guidance" ( DPMTAG)
- Highways Agency/Transport Scotland, "Design Manual for Roads and Bridges" Volume 11 "Environmental Assessment"
- Institute of Environmental Assessment and Management ( IEMA) - Guidelines for the Environmental Assessment of Road Traffic
These references were used to provide an overview of information on the environmental risks and impacts associated with road transportation, and in particular local increases in heavy goods traffic on existing road networks and adjacent receptors.
The community-level environmental impacts associated with traffic are identified by the IEA guidelines. These guidelines set out a list of environmental effects which should be assessed for significance which comprise:
- Noise and Vibration;
- Air pollution, dust and dirt;
- Driver delay;
- Accelerated wear and tear;
- Pedestrian severance, delay and amenity; and
- Accidents and safety.
As outlined in the legislative and regulatory review section, there are two rules within the IEA guidelines that can be adopted to delimit the scale and extent of the assessment:
- Rule 1: Include road links where traffic flows would increase by more than 30% (or the number of HGVs would increase by more than 30%); and
- Rule 2: Include any other specifically sensitive areas where traffic flows would increase by 10% or more.
5.3 Community impacts of traffic from onshore oil and gas development
The activities that would generate significant traffic to and from that a well pad or group of well pads are:
1. Construction and drilling- which involve the arrival of drilling equipment, drill casings and drilling water at the well pad, and the removal of bored material and drilling water from site. Variability in well depth would influence the number of vehicle movements required during this phase;
2. Hydraulic fracturing- which would require the delivery of water, proppant materials and chemicals to the well. At some locations, piped or recycled water may be available and would not require delivery;
3. Flowback removal and treatment i.e. the removal of wastewater from the well. Again, at some locations, flowback water may be recycled into the fracturing process and/or removed by pipeline;
4. All other operations, deliveries and activities associated with the well including staff movements.
The New York State DEC  provided an overview of the potential effects of road traffic as follows: " The introduction of high-volume hydraulic fracturing has the potential to generate significant truck traffic during the construction and development phases of the well. These impacts would be temporary, but the cumulative impact of this truck traffic has the potential to result in significant adverse impacts on local roads and, to a lesser extent, state roads where truck traffic from this activity is concentrated."
Broderick et al.  state that the data for New York combined with data in relation to exploratory drilling in the UK "…suggests a total number of truck visits of 7,000-11,000 for the construction of a single ten well pad ... Local traffic impacts for construction of multiple pads in a locality are, clearly, likely to be significant, particularly in a densely populated nation…" Fry  noted that noise, vibration and traffic are among the most noticeable impacts during this stage of development.
New York State DEC went on to examine some of the potential impacts of this level of transport. These include:
- Increased traffic on public roadways. This could affect traffic flows and congestion.
- Road safety impacts.
- Damage to roads, bridges and other infrastructure. This could lead to decreased road quality and increased costs associated with maintenance for roads not designed to sustain the level of traffic experienced.
- Risks of spillages and accidents involving hazardous materials.
In a review carried out for Chesapeake Climate Action Network, Ricardo-AEA commented that: " in addition to the above, the road vehicles would cause air emissions with the potential for localized air quality impacts, as well as increasing the potential for community severance (reduction in community interaction due to roads with high traffic volumes) and potentially affecting residents' quality of life."  Ricardo-AEA went on to summarise impacts in the context of the US state of Maryland as follows:
" Even at the levels described above, the impact in traffic terms associated with an individual site would be no more than "minor" in view of the short duration, although it would potentially be noticeable by local residents. The impacts include air emissions, noise and visual impact, as well as transport system effects such as infrastructure damage, congestion and effects on road safety during the period of hydraulic fracturing.
An increase in road transportation of potentially hazardous chemicals and waste materials would result in an increased risk of environmental pollution due to accidents, although these risks cannot be quantified at present. The established controls on transportation of dangerous goods would reduce the risks posed by vehicle accidents.
If a number of well pads are developed in a given area, the potential for adverse effects would be more significant, as there would potentially be a sustained increase in numbers of goods vehicle movements in a local area. The EPA (2012a NPR p14) indicates that, if extensive refracturing is required, truck traffic associated with shale gas development in New York state could become fairly continuous. In the context of Garrett and Allegany Counties (see Section 3.1.7), the impact of traffic associated with more widespread development, including the risks posed by traffic accidents, could be considered of "moderate" significance."
These potential impacts are discussed in more detail in the following sections.
5.3.2 Potential for accelerated road surface degradation
A common concern regarding traffic associated with onshore oil and gas operations relates to the risk of damage caused to road surfaces and the underlying road structure through additional loading by heavy vehicles , . One research paper considering transportation infrastructure impacts in Texas reported that the transportation of water can cause greater road damage than a static load; because the movement of water within the tank as the vehicle moves will constantly shift the weight borne by each axle and potentially cause greater road damage than a static load of equivalent weight  .
The transportation of plant, equipment and materials to and from well sites in Scotland would most likely be via heavy goods vehicle. If transport of water to and/or from the site is required, this is likely to be by road tanker. The International Energy Agency suggested that typical articulated tankers vehicle can hold around 30 cubic metres of water,  with a total laden weight of approximately 40 Tonnes. This is consistent with the figure of 28 cubic metres used to derive estimated vehicle numbers in Chapter 4. Typical rigid body tankers have a capacity of 15 cubic metres with a total laden weight of 26 Tonnes. A fully laden water tanker is close to the current limit for vehicle weight on UK roads of 40 Tonnes  .
In the UK, structural wear resulting from traffic ( i.e. fatigue cracking within the bound pavement layers and/or excessive subgrade deformation) is considered during the design stage of the road  . The damage to roads caused by cars is very limited compared with that caused by heavy vehicles. Roads are therefore designed to support a specified number of heavy vehicle loadings over their design life  .
The structural wear to a road associated with each vehicle that passes increases significantly with increasing axle load. Structural wear for pavement design purposes in the UK is taken as being proportional to the 4th power of the axle load: that is, a 50% increase in axle load would result in a five-fold increase in calculated structural wear.  In the case of a 40 Tonne fully laden articulated tanker being used to transport water, with weight approximately 90% of the current UK lorry limit, the axle loading and associated structural wear is likely to be at the upper end of the range of load and wear exerted by typical HGV traffic.
UK Roads are typically built with a 20-year design capacity based on axle loading. At the design stage future structural wear is estimated using wear factors based on projected vehicle axle loads i.e. the projected HGV traffic on any given route. The future cumulative flow is calculated in terms of million standard axles (msa).  Roads are therefore designed and constructed to different specifications depending on the projected loading from HGV traffic. Main routes and trunk roads are typically designed to withstand heavier loads than local or rural roadways where lower annual average traffic flows are projected at the road design stage.
Axle loading fatigue on roads is therefore likely to be accelerated by HGV movements associated with UOG development. Depending on the location of well pads, and the design specifications and current age of the road routes where a significant increase in HGV traffic would occur, there is a risk that the 20-year design capacity axle loading would be exceeded prematurely, particularly if there are multiple well pads in a small area with significant volumes of HGV traffic using the same access route. Roadways with greater annual flows of truck traffic would generally require reconstruction sooner than similar roadways with less truck traffic. 
The US Federal Highway Administration has reported the cost of additional heavy truck traffic associated with Marcellus Shale natural gas developments on Pennsylvania state-maintained roadways in 2011 to be between $13,000 and $23,000 per well.  In a further study by the Texas Transportation Institute, which used traffic and pavement condition data, coupled with inspection and field-collected data, to conduct a remaining pavement life analysis, it was estimated that a typical rural Texas new road would have 60% of its design life remaining after just one year with the level of traffic associated with the development of one hundred horizontal gas wells (Quiroga et al., 2012). The Texas Department of Transportation have produced the following estimated reductions in road life associated with the different phases of an onshore oil and gas development.
Table 10: Service life reductions on interstate highways, US highways, state highways and 'farm-to-market' highways associated with natural gas well operations (Source: TDT, 2012)
|Activity||Service life reduction|
|Construction||4% to 53%|
|Rig movements||1% to 16%|
|Saltwater disposal||1% to 34%|
|Average overall impact||30%|
In response to this, several state governments have introduced maintenance agreements, which require drilling companies to restore the quality of roadways to pre-drilling conditions, which in some cases drilling companies have been reported to restore roads "to equal or better condition than before they were damaged" (Brasier et al., 2011).
Accelerated degradation of non-trunk roadways would lead to increased road maintenance costs. Without further intervention, these costs would fall on the relevant highway authorities. Abramzon et al.  argue that in Pennsylvania, there are three broad types of policy responses which can be used to address these costs: cost recovery through taxes or fees focused on the drillers, policies designed to decrease damage to roadways such as truck weight limits, and altering infrastructure to make it more resilient to higher intensity activity. 
Michaels et al.  found evidence for significant road damage in Pennsylvania, and highlighted difficulties in securing payment from operators to cover road damage due to the pace of development. In the US, maintenance agreements which require UOG operators to restore roads to a minimum of pre-drilling condition have been found to be an effective way of mitigating road damage impacts and preventing these additional costs being covered by the public purse  .
This type of maintenance agreement is currently used in other parts of the United Kingdom for both developments that generate significant volumes of HGV traffic. The supplementary guidance document for onshore oil and gas published by Lancashire Council et al. specifies that pre and post commencement road surveys should be conducted to determine if any damage caused to the highway can be attributed to the development, and if so, this should be compensated by the developer. This aims to ensure that the local road network is not adversely affected and local communities are not disadvantaged  .
Similarly, Staffordshire County Council aim to secure and maintain the structural integrity of public highways via their Supplementary Planning Guidance ( SPG) for heavy commercial vehicles generated from mineral and waste developments  . The SPG requires that the effects of a development on the structural integrity of the road are quantified to avoid unnecessary maintenance burdens falling upon the public purse. Once the extent of impact has been determined this provides a basis for determining the most appropriate form of mitigation. The guidance requires that the Transport Assessment for the development should include an assessment of the impact of heavy vehicles on the road structure. The guidance also specifies that developers may be required to provide a commuted maintenance payment, to be secured via a Section 106 Agreement planning obligation under the relevant legislation for England. An appropriate sum is calculated based on the cost of maintaining the infrastructure, which is over and above that which would have been incurred by the highway authority anyway.
There is some evidence that proactive road maintenance is more cost effective than a reactive approach. Li and Mikhail conducted a case study for a stretch of 2 lane rural road in Dimmit County, US. Their analysis demonstrated that a proactive road maintenance approach was more cost effective than a reactive approach in the long term but also noted that reactive maintenance still dominates the current practice  .
5.3.3 Risk of increased accidents
Some research has been conducted regarding the potential for increased road traffic accidents attributable to changes in traffic volume and fleet composition e.g. increased percentage of heavy truck movements, from UOG operations. Concern has also been raised that the degradation of road surfaces from the heavy vehicle use could also impact on accident rates.  This research was carried out mainly in countries other than Scotland, and the findings were assumed to be applicable to Scotland, with specific exceptions as identified below.
A review of accidents and injuries to road transport drivers in Europe  reports the conclusions of a Danish analysis of road traffic accidents  whereby the following features of heavy good vehicles were concluded to increase the accident risk of trucks in comparison with passenger cars:
- The construction/dimensions etc. of trucks can contribute to situations arising that can develop into accidents - situations that would not arise with passenger cars;
- The reduced braking and evasive abilities of trucks can contribute to situations more often developing into collisions, and the collisions occur at higher speed;
- The size and weight of trucks may mean that collisions result in more serious personal injuries than similar collisions involving passenger cars;
- Driving mistakes made by heavy goods vehicle drivers may be more serious because of the weight, size, shape, manoeuvring abilities, braking abilities, etc., of the vehicle.
The EU-OSHA report also quotes analysis prepared by the Dutch accident research board  which indicates that collisions and fires involving trucks carrying dangerous substances occur fairly regularly. There is also however research which indicates that tankers carrying flammable goods have a 70-80% lower risk of crashes than heavy goods vehicles in general. This may be attributable to more stringent training of drivers of tankers carrying flammable goods, stricter standards for vehicles, and differences in the road and traffic environment in which tankers carrying flammable goods and other heavy goods vehicles travel , .
A number of regions in the United States have reported increases in the rates of accidents in recent years, correlating with the expansion of the shale gas industry. For example, the Upper Great Plains Transportation Institute (2013) reported that severe injury truck crashes in North Dakota's oil region increased by more than 1,200% between 2008 and 2012, whilst the rest of the state experienced an increase of just 147%. Similarly, in 2015 Rahm, Fields and Farmer reported that between 2009 and 2013 crash trends in the Eagle Ford Shale region of rural Texas increased by 26%, and fatalities/severe injuries by 49%, which, it is suggested, is a result of a rise in shale gas related vehicle movements.
Graham et al.  examined records of motor vehicle accidents and drilling activity in Pennsylvania from 2005 to 2012. Data on the number of traffic accidents (total vehicle accidents, heavy-truck, fatal, and major-injury accidents) per county and month were reviewed. They compared records from counties where drilling was occurring with equivalent control counties where there was no drilling activity. For counties in north Pennsylvania, their results indicated that overall vehicle crash rates were 15-23% higher during the years 2010-2012 and heavy truck crash rates were 61-65% higher during 2011-2012 than the control counties. In southwest Pennsylvania rates of fatal and major injury crash rates were 45 - 47% higher during 2012.
Graham et al. also investigated whether there was a relationship between number of new wells and crash rate. In the northern drilling comparison group, each increase of 10 wells was associated with a 3% increase in vehicle crash rate and a 9% increase in heavy-truck crash rate. The statistical model also suggested that there was a statistically significant 5% increase in fatal crash rate for each 10 additional wells drilled in the northern counties. In the southwestern drilling comparison group, the only significant finding was a 10% increase in heavy-truck crash rate associated with each 10 additional wells.
Research conducted in Texas indicated that the most likely time period for crashes was between 17.00 and 18.00, with the majority of crashes during this period involving employees' personal vehicles. Only 10% of the crashes overall involved commercial vehicles. The authors concluded that this may be caused by employee traffic at rush hour having an impact on road crashes in regions where energy industries were present  .
Another analysis of road traffic accident records has shown that workers in the US oil and gas extraction industry experience 8.5 times the rate of work-related motor vehicle-related deaths compared to all other workers in the United States. It also reports that h alf of the workers who died were either not wearing a safety belt or were ejected from the vehicle and presumably, not wearing a safety belt  . This research highlighted that low levels of seat belt use in the oil and gas extraction industry may be in part related to the culture of the work environment, consistent with the sociological profile of the workforce  . There are significant differences between seat belt legislation in Scotland and in the relevant states of the US which would be expected to result in increased seatbelt use for commercial vehicle operators in Scotland compared to the US.
5.3.4 Risk of accidental release of hazardous material during transportation
There is a risk that truck accidents could lead to chemical or wastewater spills. This could include fracturing fluid, additives, flowback water, and produced water. In the event of an accidental release, fluids can run off into surface water and/or seep into groundwater.
One example of this occurring has been found in our review, in December 2011, a truck accident in Mifflin Township, Pennsylvania released fracking wastewater into a nearby creek 
An increase in road transportation of potentially hazardous chemicals and waste materials would result in an increased risk of environmental pollution due to accidents. The established controls on transportation of dangerous goods would reduce the risks posed by vehicle accidents, but not fully eliminate such risks. 
5.3.5 Air pollution impacts
The increases in heavy vehicle numbers is also likely to result in an increase in emissions of air pollutants. The New York State Department of Environmental Conservation estimates the following increases in state-wide emissions from additional vehicle miles travelled associated with gas drilling:
- Oxides of nitrogen - 686.7 tons per year
- Volatile organic compounds - 70 tons per year
- Sulphur dioxide - 2.5 tons per year
- Particulate matter (<10 micrometres) - 34.4 tons per year
- Particulate matter (<2.5 micrometres) - 33.3 tons per year
- Carbon monoxide - 668.6 tons per year
These impacts are relatively minor in the context of state-wide emissions to air of these substances, consistent with the assessment of regional/national traffic impacts in Section 4.3.2. However, the potential for localised impacts would need to be taken into account in the environmental assessment of any UOG development. The vehicle movements for individual well pads identified in Section 4.3.1 are sufficient that long-term and short-term air quality impacts would be scoped in for consideration through the planning process. Consideration should be given to appropriate sources of data on baseline air quality, and an air quality monitoring survey may be appropriate in some circumstances.
A study by Goodman et al. (2016) estimated that a single well can result in "substantial increases in local air quality pollutants during key activity periods, primarily involving the delivery of water and materials for fracking to the site". Heavy truck movements are known to increase the levels of particulate matter and exhaust fumes in close proximity to road networks, as has been found in Garfield County, Colorado, which has experienced increased levels of PM 2.5 concentrations, which are thought to be the result of nearby tight-gas developments.  It would be important for any assessment of traffic impacts to consider dust resuspension in situations where vehicle movements would take place on unmade surfaces.
Air quality management areas ( AQMAs) exist in many parts of Scotland within which UOG development may take place. The presence of an AQMA would highlight the potential significance of air quality impacts, which would need to be given careful attention in the planning process. While an AQMA does not in principle present a bar to traffic-generating development, it may place an additional constraint on the development, which would influence the mitigation that would need to be provided to ensure that the development would have no significant effects on the AQMA or on measures being implemented by a local authority to improve air quality.
There have been several other reported impacts on local communities associated with increased traffic movements to and from UOG facilities, such as noise, which can result from heavy vehicle movements as well as drilling and completion operations, and flaring. 
A survey of interested and affected parties in the United States highlighted concerns about the by-products of the UOG operations. Noise from both site operations and transportation was highlighted as one of the most prevalent concerns  . The noise levels generated by vehicles depend on a number of variables, such as vehicle type, load and speed, type of road surface, road grade, distance from the road to sensitive receptor, road gradient, ground condition, and atmospheric conditions. 
A single passing of a HGV is a short duration noise event. However, multiple truck trips result in higher hourly average noise levels and impacts on noise receptors close to affected routes. Other factors being equal, the noise impact of truck traffic would be greater for travel along roads that do not normally have a large volume of traffic, especially HGV traffic.
Goodman et al. calculated estimated excess noise emissions from onshore UOG transportation and concluded that they appear negligible (< 1 dBA) when normalised over the duration of the well operation, but may be considerable (+3.4 dBA) in particular hours. The impacts of peak traffic flows could be greater if they occur during night-time periods. 
As such any Environmental Impact Assessment for UOG operations should consider noise as with any other development where an increase in traffic is forecast to occur.
5.3.7 Nature conservation
Gas extraction can affect biodiversity via a number of routes (Entrekin et al. 2011).  These include:
- Removal of habitat;
- Degradation of habitat ( e.g. as a result of excessive water abstraction); or fragmentation ( e.g. as a result of fencing, road construction);
- Introduction of invasive species;
- Noise and other disturbance;
- Water and land pollution.
New York State DEC highlights the potential effects on biodiversity due to invasive species as a potential concern.  Entrekin et al describe the risks to wildlife posed by sediment runoff into streams, reductions in streamflow, contamination of streams from accidental spills, and inadequate treatment practices for recovered wastewaters as "realistic threats". Entrekin et al. conclude that there are preliminary indications of detectable effects of sedimentation of watercourses due to shale gas development, and consider that scientific data are needed to ensure protection of water resources.
Farwell et al. (2016)  considered the impacts of unconventional gas development on forest habitat and breeding songbirds at a predominantly forested site in the central Appalachians from 2008 to 2015. The results of the study indicated that "shale gas development has the potential to fragment regional forests and alter avian communities". Traffic movements would be one component of this potential effect. The likely setting of shale gas development in Scotland means that impacts on remote habitats are unlikely. However, there would be a risk of harm to habitats which may be valuable in their local setting. Any such effects would need to be considered during the planning and EIA process.
5.3.8 Site grouping
All of the above impacts could be compounded if UOG developments are grouped in a relatively small area.  . This could potentially result in an intensification or an extended duration of impacts for local communities. This would need to be addressed through the strategic and local planning process.
5.4 Case studies
The case studies were reviewed to identify the likely community-level impacts that would need to be considered when appraising UOG applications, and the mitigation that could be provided to alleviate these impacts. The case studies included consideration of a wind farm site and a quarry site, because some of the features of these sites are comparable with UOG sites.
The case studies are set out in Appendix 1. The windfarm, opencast mining and quarry case studies all resulted in comparable maximum numbers of HGV movements. For example, the windfarm case study resulted in a maximum of 92 two-way HGV movements and 40 two-way worker vehicle movements per day during the construction period. This would be a relatively short period compared to the operational lifetime of a UOG site during which vehicle movements could be taking place. Conversely, HGV movements associated with opencast mining and quarrying would continue throughout the site operational lifetime.
These HGV movement numbers are higher than those which would be associated with a shale gas well pad for the Central scenario during hydraulic fracturing - 322 movements per week (about 64 per day) for an 8-week period, followed by 115 movements per week (about 23 per day) for approximately two years. Light vehicle movements for the Central UOG scenario would be similar to the windfarm scenario.
Measures to mitigate transportation impacts were proposed for each of the case study developments. These were typically to be implemented by means of a Traffic Management Plan. With this mitigation in place, traffic was found to have negligible, minor or (in some aspects) moderate impacts. It is reasonable to expect that mitigation for transportation impacts associated with UOG development, provided it takes account of the specific factors relevant to UOG development, would be effective in reducing and minimising transportation impacts to a low level. As with any comparable development, traffic impacts could not be completely eliminated, but could be reduced to a level which would be considered negligible or minor. The case studies illustrate how this would need to be evaluated on a case by case basis, and appropriate mitigation designed and implemented.
5.5 Management and mitigation measures
5.5.1 Scottish Planning System
If the current moratorium on UOG development in Scotland is lifted, the Scottish planning system would play a key role in ensuring that appropriate mitigation measures are implemented at a UOG site. The planning system is used to guide decisions about the future development and use of land and identifies the locations and conditions under which development should and should not happen.
The planning system is "plan-led" and is divided into three key parts which include:
1. Development plans which set out how places should change in the future;
2. Development management which is the process for making decisions on planning applications. Planning legislation requires that decisions on applications are guided by policies in the development plan; and
3. Enforcement, which makes sure development is carried out correctly.
The Government published the Scottish Planning Policy ( SPP) in 2014 which sets out the national planning policies which reflect Scottish Ministers' priorities for operation of the planning system and for the development and use of land. Transport forms a key role within SPP and is supported by the supplementary planning guidance ( SPG) document, Planning Advice Note ( PAN) 75, "Planning for Transport".
PAN 75 provides good practice guidance which planning authorities, developers and others should carry out in their policy development, proposal assessment and project delivery. In principle, UOG project developers should expect to carry out similar levels of assessment of traffic impacts and provide appropriate mitigation, similar to other comparable developments and in accordance with PAN 75.
There is an opportunity to develop supplementary guidance associated with assessing the merits of UOG sites and ensuring the appropriate management of development. This could be in the form of a PAN or a planning circular, or could be developed as Supplementary Planning Guidance by individual authorities. Specific transport guidelines could be developed to provide local authorities with a means to assess the traffic and transport impacts of a UOG application, and to identify appropriate mitigation. This would also assist developers in the preparation of associated documents including Environmental Statements, Traffic Management Plans etc. Local communities could refer to this guidance to identify what level of assessment, management and mitigation of transportation impacts they can expect. This would ensure that there is consistency across all planning applications coming forward for UOG sites in Scotland.
5.5.2 The EIA process
As set out in Section 3.8, any planning application for UOG development with the potential for generating significant traffic movements could be made subject to an Environmental Impact Assessment ( EIA), in view of legal obligations for larger scale development, local authority powers to require an EIA for smaller scale developments, and industry undertakings to carry out EIAs. This would include a requirement for assessment of impacts relating to traffic movements.
Traffic modelling studies are likely to be needed in support of an EIA for UOG development. The exception would be cases where the potential traffic impact is too low to warrant such a study. The starting point for traffic modelling studies is to understand the existing, or baseline, traffic flows on the road network. This information can be obtained from traffic count data, and/or from modelling and interpolation of traffic counts. Modelling analyses can then be carried out to determine the additional flows which are expected to result from the planned activity, and to identify the routes that these vehicles can be expected to follow to and from the site. Based on this data, an assessment of environmental impacts due to traffic movements can be carried out. These impacts may include noise and emissions to air, as well as risks which are not specifically environmental, such as traffic accidents.  If required, appropriate mitigation can then be devised and residual impacts assessed. Mitigation measures then need to be confirmed, implemented and monitored, as described below.
5.5.3 Identifying the need for mitigation
Following the application of Rules 1 and 2 in the IEA Guidelines, a detailed assessment of a particular road link(s) may be required. The assessment (if required) should consider the following potential environmental impacts as discussed in Section 5.2:
- Noise and Vibration;
- Air pollution, dust and dirt;
- Driver delay;
- Accelerated wear and tear;
- Pedestrian severance, delay and amenity; and
- Accidents and safety.
The assessment must determine if the proposed development has a significant detrimental impact on any of the above and identify if any mitigation measures are required. Specific measures may be identified to address one or more of the aspects above. Examples of mitigation measures include the provision of a pedestrian crossing facility to address pedestrian severance, or wheel washing facilities to minimise dust and dirt.
However, it may also be possible to provide mitigation measures which reduce the traffic impact of the proposed development to an extent that traffic impact is reduced to below the levels identified in IES Rule 1 and Rule 2. Such measures would typically be set out in a Traffic Management Plan.
These measures are likely to vary with each planning application that comes forward and would be dependent on a number of factors including (but not restricted to):
- The location of the UOG site e.g. rural, urban and the location of the site in relation to the road network;
- The number and location of sensitive receptors relative to the site such as settlements, schools, hospitals etc
- Variations across local / transport authorities with regards to approach and judgement;
- The extent of the proposals coming forward which would in turn influence the volume of traffic; and
- The standard of the road network and the existing volume of traffic carried by these roads
Any mitigation measures require to be identified during the planning application stage and should be clearly defined in the ES.
The following sections provide a guide to the transport-related mitigation measures which may be appropriate for UOG sites based on the review of UOG sites and published research. Specific measures can be expected to vary with each application that comes forward.
5.5.4 Mitigation by Design
Site selection could form a key role in reducing the traffic impacts associated with a proposed UOG site. A site with access directly onto the strategic road network would have much less of a traffic impact than a site accessed via a network of rural roads because the development traffic would not use routes of an inadequate standard, and traffic movements associated with the development would be diluted by the existing traffic.
If the construction of new roads is required, selecting sites that have an opportunity to locally source road construction material (from on-site borrow pits for example) would significantly reduce the wider traffic impacts.
A key design element for reducing the volume of traffic generated is the avoidance of road transportation of water. This could be achieved by mains supply of water, and/or re-use of flowback water from preceding hydraulic fracturing at the same site. In the Scottish context, the oil and gas industry considers that shales are less saline and are likely to contain less Naturally Occurring Radioactive Material than shale formations in England or the US. If this is the case, this would facilitate re-use of waste-water. Road movements could also be reduced by providing for removal of any produced water or flowback water which cannot be recycled by pipeline, or by on-site treatment. On-site treatment is less likely to be a cost-effective option for a single well pad. The preparation of guidelines identifying the use of such design features would allow local authorities and developers alike to narrow their area of search and to give priority to sites where these features can be achieved.
The Letham Moss case study indicated that with water delivered by mains supply, the remaining traffic levels were predicted to be below the thresholds for further assessment of detailed environmental effects. The Clackmannanshire Local Development Plan makes specific reference to transportation of water for hydraulic fracturing, and indicates that preference would be given to sites that could import water by pipeline.
Traffic impacts can also be mitigated by effective material and logistics planning. This may include the use of central warehousing, communications with suppliers, and contractual arrangements which encourage safe and considerate driving.
5.5.5 Traffic Management Plan
The primary purpose of a Traffic Management Plan ( TMP) is to minimise traffic impact associated with a proposed development. A TMP can be implemented during the construction stage, operational stage and/or decommissioning stages of a development. TMPs may not be required for all sites given that each site would vary considerably. However, in view of the nature of UOG sites, a TMP is likely to be appropriate at all stages. The TMP is an evolving document and should be updated at appropriate stages or when planned changes to the development would directly influence vehicle movements and therefore environmental impacts associated with traffic.
TMPs are often requested by local authorities at the planning consent stage by means of a prescriptive condition attached to the issued consent. There is variability between local authorities in their approach to requiring TMPs for different types of development. There is a lack of consistency with regard to the requirement to produce the TMP and with regard to the measures that should be included within a TMP.
Developers should produce TMPs with a range of measures identified within the TMP to minimise and control traffic movements and associated environmental impacts. During project development, some sections of the TMP are likely to be provisional, and would not be able to be finalised until the finer details of the development are known. Many of these measures can be readily implemented and checked, but there is in some cases a lack of enforcement from local authorities with regard to the full implementation of the TMP and its measures.
Whilst the content of a TMP varies depending on the project, the following elements should be included as standard.
Table 11: Typical contents of a Traffic Management Plan
|TMP Element||Effect / Comment|
|Identify designated routes for HGVs and general construction traffic||This is particularly important for HGVs in order to ensure that the road network is suitable to accommodate the vehicles and that traffic impacts are minimised, particularly in sensitive areas such rural villages, schools etc. The TMP should specify any junctions or road links that require to be avoided during busy periods and would require discussions with local authorities and Transport Scotland (if applicable). It may be appropriate to identify multiple routes to / from site so that the impact of HGVs is spread-out and not restricted to the same sections of road. It is likely that these routes would have been identified in the ES. However, the TMP would consider routes in more detail. As a TMP is an evolving document, it is prudent to reassess these routes after a designated period of time to ensure that they remain appropriate and that the contractor is adhering to the routeing specified in the TMP. A mechanism for surveys or independent checks should be included.|
|Access arrangements||The TMP should detail the access arrangements to the site both for staff and construction traffic / HGVs. Certain sites may have multiple access points and all relevant parties should be fully aware of the purpose of each access. For example, there may be a dedicated access for staff and another for HGVs. In addition, it may be appropriate to restrict the use of certain access points / sections of the road network at specific times of the day. This would usually be during the weekday AM and PM commuter periods. This would normally be identified in the ES, however, this should form a key part of the TMP.|
|Designation of working hours||The TMP should specify the working hours of staff and routeing / access arrangements to site should be specified taking cognisance of these working hours. It may be necessary to designate working hours in such a way that staff would not be travelling to site during the weekday AM and PM commuter peaks. This would limit the traffic impact of the development during these busy periods. As with general construction sites, HGV access to UOG sites should normally be limited to weekdays and a half day on a Saturday.|
|Staff travel arrangements / parking||The TMP should detail travel arrangements for staff. This would include working hours (as specified above) and also parking arrangements including the location of the car park(s) within the site. A Travel Plan ( TP) can also be prepared which could form an Appendix or dedicated chapter of the TMP. The purpose of the TP is to encourage trips to / from the site by sustainable modes and discourage single-occupancy private car trips. For urban sites, this would include encouraging trips on-foot, by bicycle, by public transport and by car sharing. For more rural sites, a TP would be likely to focus on encouraging car sharing. A Travel Plan Coordinator would be appointed to raise awareness of the plan and to ensure that the measures contained within the plan are implemented effectively. The Coordinator would be responsible for monitoring the success of the plan against agreed targets and would be the key point of contact for staff. The staff induction process provides an opportunity to disseminate travel arrangements. Staff should be clear with regards to their travel arrangements and should be encouraged to travel to site, where possible, by sustainable modes (including car sharing). Staff should also be clear about where to park on-site and whether there are any restrictions associated with access locations.|
|Appointment of community liaison officer||In view of the ongoing requirement for traffic access to UOG sites and potential for use of unsuitable roads, it may be appropriate to appoint a community liaison officer who would be responsible for ensuring members of the public and local businesses are kept up-to-date with the current status of the development and highlighting what measures the developer / contractor is putting in place to ensure impacts on the local community are minimised. The developer / contractor would therefore have a responsibility to disseminate this information and ensure the officer has all the necessary information.|
|Co-ordination with other sites||The TMP should provide details of any committed or planned development sites in the vicinity, particularly if the construction stages coincide. Discussions between developers / contractors should take place at the earliest opportunity so that travel arrangements, HGV routeing etc can be co-ordinated in order to minimise traffic impact. A summary of discussions should form part of the TMP. In addition, a co-ordinated approach with regards to mitigation measures can also be developed between developers and should be included within the TMP.|
|Speed limits / signage arrangements||Any amendments to speed limits in the vicinity of the site should be stated and described in detail within the TMP. This should include the location of the speed limit change, the timescales and detail any associated signage. Furthermore, any other signage proposed should be clearly stated within the TMP.|
|Traffic monitoring arrangements||It may be prudent to monitor the volume of traffic associated with the proposed development to ensure that the actual volume of traffic is in line with the calculations outlined in the ES. This is to ensure that the mitigation measures (if any) continue to be appropriate for the volume of traffic associated with the development. The TMP should clearly indicate the arrangements for these monitoring surveys, and should specific the location of the counters. This would require to be agreed with the local authority and / Transport Scotland.|
Transport management plans should be circulated to all suppliers for distribution to drivers.
In the past, TMPs have proven to be a very effective way of reducing the traffic impact associated with the development and they are often used as a "catch-all" with regard to the mitigation of traffic and associated environmental impacts. However, their success relies on a number of factors including:
- Local authorities actively monitoring the implementation of TMPs;
- Developers and contractors being proactive at implementing TMPs (also in a situation where they are not being pursued by the local authority / Transport Scotland);
- Effective communication between the contractor so that they are aware of the requirement to prepare a TMP; and
- TMPs being subject to a planning condition / Section 75 Agreement rather than a voluntary undertaking.
5.5.6 Road Condition Survey and maintenance
A Road Condition Survey (sometime called a Dilapidation Survey) can be an appropriate mitigation measure for proposed UOG sites where there is likely to be accelerated wear and tear on the road network as a result of increased heavy goods vehicles. This survey is most likely to be required when the UOG site is situated in a rural location meaning that HGVs and general construction traffic are required to use C-class roads or unclassified roads. These may be single track and are not designed to carry large volumes of heavy goods vehicles. A significant increase in heavy vehicle traffic is likely to have a detrimental impact on road surfacing and could potentially affect the full road construction.
With regard to timescales for the survey, there are a number of options including:
- Upgrade the road to a specification identified by the local authority prior to construction on-site;
- Undertake regular Road Condition Surveys throughout the lifespan of the project to ensure that the road is not deteriorating to a level where improvements are required. When the survey indicates issues, the developer / contractor would be responsible for implementing improvements or paying for mitigation to be undertaken.
In order to minimise the risk of disagreements regarding the timing and extent of improvement works, a financial agreement in line with Section 96 of the Roads (Scotland) Act 1984 could be put in place from the outset. A legal mechanism is put in place to allow the Council to recover the cost of road repairs and the mechanism would identify an extent for the surveys and potentially a limit of the value of repairs. A financial bond can be put in place by the developer which the Council can draw down against as necessary.
At this stage, there would be an opportunity to integrate the expected arrangements for road condition surveys and maintenance arrangements into specific planning policy/guidelines for UOG development.
5.5.7 Traffic Monitoring
It is recommended that traffic levels associated with the development are monitored to check that they are in line with the levels predicted in the ES. This is to ensure that any mitigation measures that were identified in the ES remain appropriate for the volume of development traffic. If this process identifies higher than anticipated traffic volumes, the outcome of this process could potentially be that additional mitigation measures require to be identified. Traffic monitoring at an appropriate frequency could form part of the TMP. However, if the local authority determine that a TMP is not required, traffic monitoring could be undertaken as a stand-alone exercise with a planning condition used to ensure its implementation.
5.5.8 Managing and enforcing mitigation measures
It is important to ensure that careful consideration is given to identifying appropriate measures to mitigate the impact of the proposed development. While these measures would differ depending on the proposal, there is a clear opportunity at this stage to develop a consistent approach with regards to identifying appropriate measures and more importantly, ensuring that these measures are managed / enforced throughout the life of the project.
In principle, the approach to identifying mitigation measures for traffic associated with a UOG site should not be any different to other environmentally sensitive applications (that require the preparation of an ES) such as windfarms, quarries, overhead transmission lines etc. However, there is a lack of consistency in implementation and management of traffic management measures across the industry. In some cases, mitigation measures are identified in the ES and may be backed up by planning condition, but are not always fully implemented in practice. This is largely due to:
- Difficulties experienced by the relevant authorities in monitoring whether or not these measures have been implemented - for example, as a result of cost / resourcing issues;
- Lack of effective communication between the planning team and the appointed contractor; and
- Lack of a constructive or pro-active approach from developers, resulting in measures not being implemented unless prompted
The "tools" needed to mitigate the traffic impacts of UOG sites are available, and a well-established mechanism for identifying the need for mitigation is already in place. However, ensuring that appropriate arrangements are in place for specifying, managing and enforcing these measures is an area that should be addressed ahead of the implementation of UOG activity in Scotland.
One effective way of ensuring the measures are implemented is to appoint an independent Compliance Officer ( CO) who would be paid for by the developer. The CO would be responsible for ensuring that the developer / contractor is satisfying planning conditions and other legal agreements (such as Section 75 Agreements or Section 96 Agreements). This should include any measures that have been identified through the ES including TMPs, Road Condition Surveys and Traffic Monitoring as well as any other measures identified in the ES to address driver delay, pedestrian delay etc which may have been subject to stand-alone planning conditions.
Planning policy for UOG sites could ensure that there is a requirement to appoint a CO post planning agreement. This could be subject to specified thresholds ( e.g. maximum forecast daily traffic flow above an identified level). This would provide confidence that mitigation measures would be implemented and managed throughout the life of the project. It may potentially be possible to link the Compliance Officer role with a liaison officer, if appointed (see Table 11).