Scottish Trunk Road Infrastructure Project Evaluation 1YA Evaluation Report for A9(T) Crubenmore Extension
Detail of Evaluation A9(T) Crubenmore Extension
3 A9(T) CRUBENMORE EXTENSION
The A9(T) between Perth and Inverness is approximately 179 kilometres in length and is located across Perth & Kinross and Highland Council areas. It is a key transportation corridor in the north of Scotland, linking the Highlands and Islands with Central and Southern Scotland.
The A9(T) Crubenmore Extension project involved the construction of approximately 2.7 kilometres of on-line dual carriageway, from the junction of the A9(T) and the U282 'Dalwhinnie to Crubenmore Road' (approximately 5.5 kilometres to the south of Newtonmore) to approximately 0.5 kilometres south of the junction of the A9(T) and the access to Laggan and the Invernahavon Caravan Park.
The project provided an extension to the existing 1.6 kilometres of dual carriageway located directly to the south of the scheme extents to provide approximately 4.3 kilometres in total of continuous dual carriageway. As part of the improvement, the existing cycle track (National Cycle Route NCN7) was retained, maintaining its current alignment with a few localised realignments as required. The general location of the project is shown in Figure 3.1.
The A9(T) Crubenmore Extension project was officially opened to traffic on 26 September 2011. The final scheme involved departures from Design Standards for dual carriageway schemes, which were approved by the Transport Scotland's Standards Branch.
Rationale and mandate for the scheme
The project was implemented as part of a wider Route Action Plan for the A9(T) developed in 1993, with objectives to improve the safety, comfort and reliability of journey times on the route. The decision to incorporate the A9(T) Crubenmore Dual Carriageway extension scheme into the Trunk Roads Programme was taken following a Strategic Roads Review.
In combination with other overtaking projects previously implemented on the A9(T) and the strategic dualling programme of the route currently being progressed by Transport Scotland, the A9(T) Crubenmore Extension scheme was targeted principally to improve the operational performance and safety of the route by reducing driver stress and journey times through the provision of an increased number of overtaking opportunities at this location. Approval to proceed with the scheme was made by Transport Scotland in June 2010.
The objectives of the A9(T) Crubenmore Extension project were set as follows:
- improve the operational performance and level of service and safety on A9 by reducing the effects of driver stress and journey times;
- improve and increase the number of overtaking opportunities to eradicate the conflicts between long distance users and local/agricultural traffic;
- wherever practicable, incorporate measures for non-motorised users. In particular, cycling proposals shall be designed in accordance with the "Trunk Road Cycling Initiative" which supports the SUSTRANS Millennium National Cycle Network;
- maintain the asset value of the A9 route;
- mitigate the environmental impact of the new works where possible; and
- achieve good value for money for both taxpayers and transport users.
3.2 Evaluation Methodology
As set out in Section 2.1, this One Year After report presents the results of a One Year Evaluation of the A9(T) Crubenmore Extension project, focusing on:
- The operation of the scheme: how the scheme is operating (in terms of traffic and safety in particular); and
- Objectives: whether the scheme is on-track to achieving its objectives.
Furthermore, a process evaluation has been carried out, which considers how the project was implemented across the elements of project cost, programme and key processes. A commentary on this is included under other criteria (e.g. Road Safety Audit (RSA) process under Safety), the main aspects of process evaluation have been summarised above in the Summary of Impacts (Section 1 of this report).
This evaluation was supported by a site visit carried out in November 2013. External stakeholder views were invited from the Highland Council, Cairngorms National Park Authority and the Road Haulage Association (RHA). No comments were received from either the Highland Council or Cairngorms National Park Authority. Feedback was received from the RHA, which is presented within the report.
The evaluation is supported by the consideration of pre and post opening comparison of operational indicators, which focuses on network traffic indicators including traffic volumes and travel times, presented in the following section.
The locations of the Automatic Traffic Counters (ATC) within the study area are shown in Figure 3.1.
Comparison Between Pre and Post Opening Traffic Flows
The Annual Average Daily Traffic (AADT) flows pre and post project opening on the A9(T) route within the vicinity of the project are presented in Table 3.1.
|ATC Reference||AADT by Year|
|A9(T) Ralia - North of B9150 Junction (North of the project)|
|A9(T) Dalwhinnie (South of the project)|
A comparison between pre and post opening traffic volumes on the A9(T) within the vicinity of the scheme indicates that traffic flows in 2012 were approximately 400 vehicles per day (vpd) lower than 2007 flow levels. Traffic volumes between 2010 and 2012 reduced by approximately 70 vpd (1%) although analysis of the long term trends in annual traffic flows suggest that the volume of traffic on this section of the A9(T) had been falling for a number of years prior to the opening of the project.
Given the nature of the A9(T) Crubenmore Extension project, small reductions in traffic levels are not likely to be as a consequence of changes to the carriageway standard and may be as a result of reductions in traffic volumes across the wider trunk road network due to the economic downturn experienced during the evaluation period.
Comparison Between Predicted and Actual Traffic Flows
The opening year flow comparisons for the A9(T) Crubenmore Extension project are based on AADT flows from 2012 as this was the first full year of reliable traffic data available from Transport Scotland's traffic counters within the vicinity of the project.
As part of the project's appraisal, National Road Traffic Forecasts (NRTF) central traffic growth factors were applied to the 2004 base year traffic flows to derive opening and future year modelled assessment traffic flows.
As AADT flows were not available from the information presented as part of the project's appraisal for either the opening or future modelled assessment years, AADT flows have been derived from the economic assessment of safety impacts element of the appraisal.
While it is acknowledged that the flows within the project's appraisal and the assessment of safety impacts may not be entirely consistent, it is judged that the AADT flows derived from the assessment of safety impacts are a suitable representation of the flows used within the project's appraisal.
Predicted traffic flows for 2012 have been derived by factoring the 2006 base year flows used in the assessment of safety impacts with NRTF central traffic growth factors.
A summary of the actual and predicted traffic data is shown in Table 3.2 below.
|ATC Ref||Actual AADT*||
(Predicted - Actual) /
|A9(T) Dalwhinnie (South of the project)|
* 2012 flows (first full year of ATC data available)
The comparison between predicted and actual AADT flows in Table 3.2 indicates that the predicted 2012 flow was 10.9% greater than the observed 2012 flow under the central traffic forecast scenario.
Whilst this comparison indicates that traffic growth on the A9(T) has fallen significantly short of the assumed NRTF forecasts, it is recognised that there has been a general fall in traffic volumes across the wider trunk road network in recent years due to the economic downturn that may in part account for the difference.
As the opening of this scheme predates the implementation of STRIPE guidance, pre-opening overtaking surveys were not carried out for this scheme Post-opening overtaking surveys have therefore not been carried out in the absence of a comparable baseline.
However, it is reasonable to assume that, due to the nature of the improvement, (a single 2-lane carriageway upgraded to a dual 2-lane carriageway, providing a 2.7 kilometre extension to the existing section dual carriageway at this location), the number of unambiguous overtaking opportunities will have increased in both directions of travel as a direct result of the project.
Comparison Between Pre and Post Opening Journey Times
Pre-opening journey time surveys were carried out for the A9(T) Crubenmore Extension project in June and September 2004 to validate the traffic model used in the assessment of the project. Post opening journey time surveys were carried out in February 2014 to provide an indication of the changes in average journey times along the A9(T) between Dalwhinnie and Kingussie.
The extents of the journey time survey route are shown in Figure 3.2.
The average pre and post opening journey times along with the savings in travel time are shown in Table 3.3 below.
|Direction||Average Journey Time||Time Savings (mins / secs)||% Saving|
|Observed Pre Opening (2004)||Observed Post Opening (2014)|
|Northbound||18 mins 16 secs||15 mins 53 secs||2 mins 23 secs||13%|
|Southbound||18 mins 39 secs||16 mins 32 secs||2 mins 7 secs||11%|
|Northbound||16 mins 26 secs||15 mins 34 secs||52 secs||5%|
|Southbound||17 mins 27 secs||17 mins 1 sec||26 secs||3%|
|Northbound||16 mins 24 secs||15 mins 19 secs||1 min 5 secs||7%|
|Southbound||17 mins 51 secs||17 mins 20 secs||31 secs||3%|
Examination of the pre and post opening journey times, presented in Table 3.3, indicates that, between Dalwhinnie and Kingussie, average journey time savings of between 30 seconds and 2 minutes are typical following the opening of the scheme.
Further examination of the pre and post opening journey times indicates that journey time savings appear to be more pronounced during the AM period, with savings of between approximately 2 minutes and 2 minutes 30 seconds (11% and 13%) in the southbound and northbound directions of travel respectively. This can be in part explained by the higher journey times (18mins plus) recorded, pre scheme opening in the morning peak hour. This differs substantially from the other five datasets and is likely to be attributed to higher AM period traffic volumes during this survey.
Journey time savings during the Inter Peak and PM periods appear to be of a lower magnitude when compared to the AM period. Savings of between approximately 30 seconds and 1 minute (3% and 5%) in the southbound and northbound directions of travel respectively were observed during the Inter Peak period with savings of between approximately 30 seconds and 1 minute (3% and 7%) in the southbound and northbound directions of travel respectively observed during the PM period.
Comparison Between Predicted and Actual Travel Times
The available predicted 2022 journey time savings have been compared with the journey time savings collected post opening of the scheme in 2014. While there is a significant period (eight years) between the predicted and actual journey times, the predicted flow for 2022 is well below the capacity of the A9(T) at this location, which suggests that journey time savings will remain broadly similar between 2014 and 2022.
The comparison of predicted and actual journey time savings are shown in Table 3.4 below. The actual savings recorded below are directional averages based on the travel time data shown in Table 3.3 previously.
|Direction||Average Daily Journey Time||Comparison (mins / secs)|
|Predicted Saving (2022)||Actual Saving (2014)|
|Northbound||-||1 min 38 secs||-|
|Southbound||-||2 mins 43 secs||-|
|2-Way||25 - 30 seconds||1 min 56 secs||1 min 26 secs - 1 min 31 secs -|
The comparison between the available predicted and actual journey time savings presented in Table 3.4 indicates a predicted saving of between 25 and 30 seconds in both directions of travel following the opening of the scheme. This is in comparison to actual savings of approximately 2 minutes in both directions of travel, derived from the observed journey times, indicating that actual savings in journey times are considerably greater than forecast as part of the scheme's assessment.
The following section provides a summary of the assessment of environmental mitigation measures proposed for the A9(T) Crubenmore Extension scheme. A fuller report is provided in Appendix B.
Review of Environmental Mitigation Measures
The environmental mitigation measures originally proposed for the A9(T) Crubenmore Extension project were obtained from the project's ES. A review of the environmental mitigation measures was carried out in November 2013, as well as a review of the as-built scheme plans. Following this review a site visit was undertaken to establish whether or not the proposed mitigation measures as set out in the Schedule of Committed Mitigation within the ES had been implemented.
The ES for the scheme proposed mitigation measures to address impacts under the following criteria:
- Water Quality, Drainage and Flood Defence
- Biodiversity and Habitats
- Visual Amenity
Much of the mitigation which was included within the ES has been implemented on site, with tree planting having been carried out at a number of locations along the northbound carriageway to mitigate against loss of nesting habitat. Overall, the design of the scheme and the implementation of the landscaping and planting mitigation have minimised the visual impact of the scheme and made it in-keeping with the wider landscape character of the area. This was accomplished particularly well along the northbound carriageway and on the embankment towards the cycle path where the creation of a naturalistic transition between verges, cycleway and woodland has been achieved.
The site inspection did however, highlight that the implementation of some measures had not been provided including whether the provision of an impermeable barrier to collect embankment and field drainage was used and whether a native hedgerow, that was to be planted to encourage birds to fly higher than the height of traffic, was provided. A review undertaken during the detailed design stage highlighted that these measures would not have contributed to the scheme integration into the environment. As part of this evaluation a further review has confirmed that their absence was considered not to have had a material detrimental impact on the general integration of the project into its surroundings.
The proposed scheme was not considered to generate any additional traffic, and therefore no issues were identified in relation to noise and vibration, global and local air quality. It was confirmed that a low noise thin surface course was laid.
Environment: Key Findings
The majority of the mitigation which was included within the ES has been implemented on site, is in good condition and is operating as expected.
There were a small number of mitigation measures that could not be confirmed during the site inspection, such as the use of an impermeable barrier to collect embankment and field drainage and the provision of a native hedgerow that was to be planted to encourage birds to fly higher than the height of road traffic. A subsequent review indicated that these mitigation measures were not provided following a review at the detailed design stage, however it is considered that there is no material detrimental impact on the surrounding environment.
The site inspection highlighted that the landscaping and visual amenity measures implemented may not be seen at their best only one year following opening and during the winter period. However, it is expected over time that natural regeneration will allow further assimilation of the scheme into the wider landscape and create a more naturalistic transition between the boundaries of the scheme and the surrounding environment.
Transport Scotland continues to robustly consider ES commitments to ensure they remain appropriate to the project.
Comparison Between Pre and Post Opening Personal Injury Accident Numbers
The locations and severities of accidents occurring within the vicinity of the A9(T) Crubenmore Extension project 3 years before and 1 year after project completion are shown in Figure 3.3a and Figure 3.3b.
A summary of the personal injury accident data is shown in Table 3.5.
|3 Years Before|
|1 Year After|
As can be seen from Table 3.5, one personal injury accident (one slight) occurred in the 1 year period following the opening of the project in comparison to two personal injury accidents (two slight) in the 3 years before opening.
Road Safety Audits
The RSA process has been followed, with Stage 1, 2, 3 and 4 Audits carried out. The Stage 4 Audit, undertaken in December 2012, confirmed that one slight accident had occurred within the vicinity of the scheme in the 1 year period following the opening of the project. However no conclusions can be drawn that would suggest road safety deficiencies in the scheme as the accident involved a northbound vehicle skidding and striking the central reserve in wet conditions. The Stage 4 RSA recommended that accidents within the vicinity of the scheme continue to be monitored.
Safety: Key Findings
An assessment of the 1 year post opening personal injury accidents and the findings from the Stage 4 RSA suggests that the A9(T) Crubenmore Extension project is operating safely.
The Stage 4 RSA recommended that accidents within the vicinity of the scheme continue to be monitored.
Transport Economic Efficiency
The comparisons between predicted and actual traffic flows and travel times, presented in section 3.3, can be considered a proxy for whether the predicted economic benefits of the project are likely to be realised.
Comparison Between Predicted and Actual Traffic Flows
The comparison indicates that the predicted 2012 flows were up to 10.9% greater than the observed 2012 flows on the A9(T) within the vicinity of Crubenmore. This overestimation may in part be due to the prediction being undertaken before the economic downturn.
Comparison Between Predicted and Actual Travel Times
The comparison of predicted and actual travel times indicates that the predicted journey time savings are approximately 1 minute 30 seconds less than the observed average journey time savings.
The RHA offered feedback on the scheme for the purposes of this Evaluation report. The RHA stated that the A9(T) Crubenmore Extension scheme had indeed helped to reduce driver frustration by enabling safe overtaking, which is in-line with the objectives set for the scheme.
Economy: Key Findings
While actual AADT flows are likely to be lower than predicted, a difference between predicted and actual journey time savings of this magnitude suggests that the economic benefits of the project may have been underestimated due to external factors that could not have readily been foreseen at the time of assessment.
3.7 Accessibility & Social Inclusion
As part of the improvement, the existing cycle track (National Cycle Route NCN7) was retained, maintaining its current alignment with a few localised realignments as required along the length of the scheme.
A Stage 3 Cycling Audit was carried out for this scheme in November 2011, reporting on the facilities for pedestrians and cyclists. The Cycling Audit records that the horizontal alignment of the route is generally without problems and sightlines are appropriate, however, there are two sections of the route where the vertical alignment is relatively steep however the Design Team have indicated the design is to standard where possible. Gradients of this nature can be expected by users given the rural location and long distance nature of the route.
The audit also records that the cross section of the route narrows at two locations at tie-ins to the old A9 carriageway which could result in issues for users of the route in addition to potential drainage issues such as localised ponding that requires to be monitored.
The audit highlighted that an issue with limiting the number of equestrian users who previously crossed the A9 from the cycle path to connect with the existing section of General Wade's Military Road. This manoeuvre had not been highlighted during the scheme's development, consultations and Statutory Process.
Through consultation with concerned parties, it has been agreed that an underpass will be provided between the upgraded U2837 side road junction and the upgraded Etteridge Estate Access. Transport Scotland is now developing proposals for this underpass as part of the wider A9 Dualling strategy with respect to accessibility and non-motorised Users.
Local disabled and visually impaired groups were not consulted as given the remote & rural nature of the site they were not considered to be 'interested user groups'. A DDA Audit was not undertaken for these reasons.
The Audit concluded that the cycling provision included as part of the project was satisfactory. During the environmental mitigation measures review, it was observed that no cyclists and / or pedestrians were present on site. No evidence has been found to confirm whether there has been a change in the levels of use of this route by active travel users.
Given the rural nature of the project, it is unlikely that significant accessibility improvements will have been felt by local active travel users and it is difficult to conclude whether any wider accessibility impacts have resulted from this active travel element of the project.
Accessibility & Social Inclusion: Key Findings
The existing cycle track (National Cycle Route NCN7) was retained as part of the improvement, maintaining its current alignment with a few localised realignments as required along its length, however, observations made during a site visit indicated that the facilities were not regularly used. Given the rural nature of the project, it is difficult to conclude whether local accessibility for pedestrians and cyclists has been enhanced as a result of the project.
The Stage 3 Cycle Audit recommended that the facilities continue to be monitored to confirm that no drainage issues exist, any unfavourable user comments relating to the topography of the route be reviewed, minor remedial works be undertaken to better define the edge of the route and provision of appropriate signage for different user groups be considered, if required.
Comparison Between Predicted and Out-turn Costs
The outturn and predicted project costs are shown in Table 3.6.
|Out-turn Cost||Predicted Cost||Difference (Out-turn - Pred)|
|@ June 2013||
Mid 02 Prices in
2002 at 3.5% Discount
Jun 10 Prices
incl 15% OB
Prices in 2002 at
Mid 02 Prices in
2002 at 3.5% Discount
Cost to Government: Key Findings
The out-turn cost of the A9(T) Crubenmore Extension project is approximately £0.62m (8%) lower than was predicted at the time of assessment.
3.9 Value for Money
The economic appraisal results for the A9(T) Crubenmore Extension project predicted a Net Present Value (NPV) of £3.58m and Benefit to Cost Ratio (BCR) of 1.54 under the central traffic forecast scenario.
Based on the comparisons presented in sections 3.3 and 3.8, which suggest that the benefits may have been underestimated and indicate that the out-turn cost is lower than predicted, the NPV and BCR of the project may be greater than predicted.
Value for Money: Key Findings
Lower outturn costs and lower traffic volumes than forecast mean that the project's original BCR of 1.54 is unlikely to have changed significantly, meaning the project still offers value for money. This should however be reviewed after three years or more to determine whether the scheme continues to offer value for money in the longer term.
3.10 Progress Towards Achieving Objectives
As specific indicators to measure the performance of the A9(T) Crubenmore Extension project against its objectives have not been developed, an initial indication of how the project is progressing towards achieving its objectives is based on the pre-opening data available, supplemented by post opening data collected as part of the evaluation.
A summary of the evaluation, providing an indication of how the A9(T) Crubenmore Extension project is progressing towards achieving its objectives, is presented in Table 3.7.
|Improve the operational performance and level of service and safety on A9 by reducing the effects of driver stress and journey times||
The provision of the dual 2-lane carriageway is judged to have a positive impact on the number of overtaking manoeuvres, which as a consequence helps to reduce platooning.
Based on the evaluation of other projects where provision for overtaking has been improved and for which journey time data is available, the provision of the dual 2-lane carriageway is judged to have a positive impact on journey times.
An assessment of the 1 year post opening personal injury accidents and a review of the Stage 4 RSA report, suggests that the A9(T) Crubenmore Extension project is operating safely.
|Improve and increase the number of overtaking opportunities to eradicate the conflicts between long distance users and local/agricultural traffic||
While pre and post opening overtaking surveys are not available, the upgrade from single 2-lane carriageway to dual 2-lane carriageway is judged to have a positive impact on the number of overtaking manoeuvres, which as a consequence helps to reduce platooning.
Stakeholder feedback from the Road Haulage Association supports this assertion.
|Wherever practicable, incorporate measures for non-motorised users. In particular, cycling proposals shall be designed in accordance with the "Trunk Road Cycling Initiative" which supports the SUSTRANS Millennium National Cycle Network||
As part of the project, the existing cycle track (National Cycle Route NCN7) was retained, maintaining its current alignment with a few localised realignments as required along the length of the scheme.
Cycling proposals were designed in accordance with the 'Trunk Road Cycling Initiative'. A Stage 3 Cycle Audit was carried out for the project, which discussed cycling provisions and made a number of recommendations.
|Maintain the asset value of the A9 route||Given the nature of the A9(T) Crubenmore Extension project, which involved replacing 2.7 kilometres of existing single carriageway with 2.7 kilometres of dual 2-lane carriageway, the asset value of the A9(T) between the project tie-in points is likely to have increased thus maintaining the value of the route.||+ve|
|Mitigate the environmental impact of the new works where possible||
The majority of measures committed within the Environmental Statement are in place. Whilst some measures could not be confirmed during the site inspection and the condition of others may not have been as expected, these issues are not considered to have had a material detrimental impact on the general integration of the project into its surroundings.
It is likely, given the lower traffic volumes and the shorter journey times over the scheme's length, that this will have a beneficial impact on vehicle emissions.
|Achieve good value for money for both taxpayers and transport users||
The A9(T) Crubenmore Dual Carriageway Extension project forms part of a series of improvements along the A9(T) corridor that can be expected to provide benefits to transport users and help encourage economic development within the north of Scotland and beyond.
The project's NPV and BCR is likely to be similar to that at the time of assessment due to the lower outturn scheme costs being cancelled out by lower actual traffic volumes.
+ve Initial indication(s) that objective may be achieved
= Progress towards achievement of objective cannot be confirmed
O Initial indication(s) that objective may not be achieved