Assessment Summary

Introduction

The DMRB Stage 2 assessment has assessed the options, taking account of constraints, potential environmental (including community and individual human impacts), engineering and traffic and economic effects to identify an Emerging Preferred Route Option. Transport Scotland’s and the community’s objectives have also been considered, as well as feedback from the public and other stakeholders, including that obtained through the A9 Co-Creative Process.

As agreed, as part of the A9 Co-Creative Process, the Emerging Preferred Route Option from the DMRB Stage 2 assessment will be presented to Scottish Ministers for consideration. Should the assessment identify an Emerging Preferred Route Option that is different to the Community’s Preferred Route Option (Option ST2A), both options will be presented to Scottish Ministers for consideration. Scottish Ministers will then confirm a Preferred Route Option for the Pass of Birnam to Tay Crossing section of the A9 Dualling Programme.

Preferred Route Option Assessment

A summary of the key findings of the DMRB Stage 2 assessment is given below for each route option.

Option ST2A

Key Benefits

Reduced traffic flows on Perth Road (between Murthly Junction and Station Road) compared to the Do-Minimum scenario;
The joint lowest overall adverse effect on cultural heritage and includes a significant beneficial effect on the setting of the Category A Listed Dunkeld & Birnam Station from re-establishing the physical connection between the station and Birnam via Station Road;
Direct vehicular and pedestrian connection provides opportunities for the sustainable reuse of the station building. Potential for providing Equality Act 2010 compliant access between station platforms can be investigated in conjunction with Network Rail and Transport Scotland (Rail);
Provides the potential for creation of additional undesignated open space on top of the cut and cover tunnel, which could provide amenity space for the community;
Results in the fewest significant adverse effects and greatest number of significant beneficial effects in relation to operational noise, particularly for noise sensitive receptors in Birnam, when compared with the at-grade options (Options ST2C and ST2D); and
Combination of the provision of additional open space and the beneficial effects in relation to noise results in the lowest overall effect on human health and wellbeing.

Key Disbenefits

Speed limit of 50mph proposed for safety between the southern extent of the scheme and the proposed Dunkeld Junction, resulting in reduced travel time benefits;
Requires significant excavation to form the 1.5 kilometres cut and cover tunnel, with significant disposal and lorry movements;
Complex road drainage required, particularly due to the lowered road alignment, existing corridor topography and narrow corridor;
Construction of the 1.5 kilometre cut and cover tunnel in such a constrained and sensitive corridor will be complex, with tunnel walls constructed using 3,700 large diameter bored piles. Installation will require heavy plant in close proximity to residential properties, Dunkeld & Birnam Station and the Highland Main Line railway;
Includes an at-grade roundabout at Dunkeld, which is a Deviation from recommendations for a D2AP (sub-category c) standard. Possibility of queuing within the cut and cover tunnel in the event of an accident occurring on the roundabout;
Lowest level of economic benefits at the highest cost;
Construction duration and requirement for extensive piling results in the greatest overall effect on noise and vibration and human health during construction;
Scale and nature of construction results in the highest overall effect on material assets and waste, and climate;
Inchewan Burn would require to be lowered by approximately 8 metres, resulting in significant changes to its form and function, impacting fish passage and fragmenting habitat;
Potential for direct and indirect impacts on businesses and community assets during construction, given the 4 ½ to 5 years expected construction duration;
Acquisition of Birnam Industrial Estate, which requires demolition of commercial properties;
Significant effect on View from the Road and the Special Qualities of the NSA; and
Although assessed as having the lowest overall effect on Cultural Heritage, there is a significant adverse effect on the setting of the Category A Listed Dunkeld & Birnam Station resulting from the loss of the station forecourt.

Option ST2B

Key Benefits

Includes a 70mph speed limit throughout, consistent with the overall A9 Dualling Programme;
The joint lowest overall adverse effect on cultural heritage and includes a significant beneficial effect on the setting of the Category A Listed Dunkeld & Birnam Station;
Direct vehicular and pedestrian connection provides opportunities for the sustainable reuse of the station building. Potential for providing Equality Act 2010 compliant access between station platforms can be investigated in conjunction with Network Rail and Transport Scotland (Rail);
Results in significant beneficial effects in relation to operational noise, particularly for noise sensitive receptors in Birnam with fewer significant adverse effects when compared with the at-grade options (Options ST2C and ST2D); and
Does not require the acquisition of Birnam Industrial Estate.

Key Disbenefits

Requires significant excavation to form the underpass structure, with significant disposal and lorry movements;
Complex road drainage required, particularly due to the lowered road alignment, existing corridor topography and narrow corridor;
Construction of the 150 metre long underpass in such a constrained and sensitive corridor will be complex, with walls constructed using 860 large diameter bored piles. Installation will require heavy plant in close proximity to residential properties, Dunkeld & Birnam Station and the Highland Main Line railway;
Increases traffic flows on Perth Road (north and south of Station Road) through the omission of a southbound diverge slip road at Birnam Junction;
Includes an at-grade roundabout at Dunkeld, which is a Deviation from recommendations for a D2AP (sub-category c) standard;
Scale and nature of construction results in an intermediate overall effect on material assets and waste, and climate;
Inchewan Burn would require to be lowered by approximately 6 metres, resulting in significant changes to its form and function, impacting fish passage and fragmenting habitat;
Potential for direct and indirect impacts on businesses and community assets during construction, given the 4 to 4 ½ years expected construction duration;
Significant adverse effects on landscape as there is limited scope to integrate the underpass into the surrounding landscape; and
Although assessed as having the lowest overall effect on Cultural Heritage, there is a significant adverse effect on the setting of the Category A Listed Dunkeld & Birnam Station resulting from the loss of the station forecourt.

Option ST2C

Key Benefits

Includes a 70mph speed limit throughout, consistent with the overall A9 Dualling Programme;
Incorporates grade separated junctions throughout, fully compliant with the D2AP (sub-category c) standard;
Provides the greatest travel time benefits for road users, due to the inclusion of grade separated junctions throughout;
No significant drainage issues anticipated;
Slight beneficial effect from the improved connection between the Category A Listed Dunkeld & Birnam Station and Birnam;
Replacement car park and pedestrian underpass would provide some opportunities for the sustainable re-use of the station building;
No direct impact on Inchewan Burn or fish passage;
Reduced direct and indirect impacts on businesses and community assets during construction;
Fewer significant adverse noise and vibration effects during construction than the lowered route options (Options ST2A and ST2B); and
Equality Act 2010 compliant access to Dunkeld & Birnam Station and southbound platform through provision of a new underpass structure, with potential for providing compliant access to the northbound platform.

Key Disbenefits

Requires import of acceptable fill material;
Requires construction of low-height retaining walls on the east side of the A9 to the immediate south of Dunkeld Junction. A further retaining wall (up to 14 metres in height) required in the locality of the River Braan crossing;
Increases traffic flows on Perth Road (north and south of Station Road) through the omission of a southbound diverge slip road at Birnam Junction;
No direct vehicular access to Dunkeld & Birnam Station, with parking provided on the site of Birnam Industrial Estate;
Scale and nature of construction results in an intermediate overall effect on material assets and waste, and climate;
Acquisition of Birnam Industrial Estate, which requires demolition of commercial properties;
Significant adverse impact on visual receptors and landscape character as a result of the raised vertical alignment and greater prominence of road infrastructure associated with the grade separated Dunkeld Junction;
Significant adverse effect on the setting of the Category A Listed Dunkeld & Birnam Station from the permanent loss of the forecourt and the visible presence of the carriageway; and
Results in a reduced number of beneficial operational noise effects and increased number of adverse effects when compared to the lowered route options (Options ST2A and ST2B).

Option ST2D

Key Benefits

Includes a 70mph speed limit throughout, consistent with the overall A9 Dualling Programme;
Provides comparable operational benefits to the other options but at a lower cost, therefore performing better in economic terms;
No significant structures required;
No significant drainage issues anticipated;
Largely at-grade, therefore no significant excavations or embankments necessary;
No substantial piling activity;
Scale and nature of construction results in the lowest overall effect on material assets and waste, and climate;
Slight beneficial effect from the improved connection between the Category A Listed Dunkeld & Birnam Station and Birnam;
Replacement car park and pedestrian underpass would provide some opportunities for the sustainable re-use of the station building;
No direct impact on Inchewan Burn or fish passage;
Reduced direct and indirect impacts on businesses and community assets during construction;
Fewer significant adverse noise and vibration effects during construction;
Equality Act 2010 compliant access to Dunkeld & Birnam Station and southbound platform through provision of a new underpass structure, with potential for providing compliant access to the northbound platform;
Lowest overall effect on the River Tay (Dunkeld) NSA and its Special Qualities; and
Lowest overall effect on visual amenity as much of the existing roadside vegetation would likely be maintained and views from adjacent visual receptors would be relatively unchanged.

Key Disbenefits

Increases traffic flows on Perth Road (north and south of Station Road) through the omission of a southbound diverge slip road at Birnam Junction;
Includes an at-grade roundabout at Dunkeld, which is a Deviation from recommendations for a D2AP (sub-category c) standard;
No direct vehicular access to Dunkeld & Birnam Station, with parking provided on the site of Birnam Industrial Estate;
Acquisition of Birnam Industrial Estate, which requires demolition of commercial properties;
Significant adverse effect on the setting of the Category A Listed Dunkeld & Birnam Station from the permanent loss of the forecourt and the visible presence of the carriageway; and
Results in a reduced number of beneficial operational noise effects and increased number of adverse effects, particularly in Birnam when compared to the lowered route options (Options ST2A and ST2B).

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