3 Route Sub-Options and Junction Strategy 3.2 Junction Strategy 3.3 Public Exhibition 3.4 Cost Estimates

3 Route Sub-Options and Junction Strategy

During the re-start workshop the previously published route was reviewed and further sub-options identified that had the potential to meet the scheme objectives (see Section 1.7). These sub-options take into account changes since 1995 in design standards, environmental constraints and legislation together with comments received following the publication of draft Orders and public exhibition held in 1996.

During the re-start workshop concerns were raised about the potential impacts of the previously published route (Sub-option 1) on properties at Orrock and Delfrigs. This led to the generation of other sub-options which sought to reduce these potential impacts. These sub-options consisted of a westerly option (Sub-option 5); an option that reduced the impact on the hill east of Orrock House and sub-options which followed a route east of the existing A90 through the Menie Estate (Sub-options 2 and 3).

It was also determined that the design team should develop a junction strategy that would consider grade-separated junction options to both the north and south of Balmedie (the original scheme only catered for access to the north).

During original work on route options carried out in the 1990s, an option to the west of the existing A90 was briefly considered but not taken forward because of its potential landscape impact. Due to the potential benefits to people it was decided to revisit a western option (Sub-option 5) in more detail. The sub-options which were developed are shown in Figures 3.1 to 3.5 and each option is described in more detail below.

3.1.1 Sub-Option 1 (Red)

The route for Sub-option 1 diverts west from the existing A90 at the termination of the existing dualled section and passes between the Cock and Bull Public House and South Orrock before sweeping around the east side of the hillock near Orrock House. It then crosses to the east of the existing A90 at Delfrigs and remains east of and generally parallel to the existing road past Foveran before re-joining the existing road at Fountainbleau.

Integration with the local road network commences at the north of Balmedie. As the existing main artery is the existing road it would be linked into Balmedie at the north of the village past "The Bungalow". Access along the existing road would be maintained through the cutting at Delfrigs by means of an overbridge. Local access to individual properties would also be maintained by a series interlinking minor access roads.

The B977 Dyce Road would be maintained by the provision of a new link to the Balmedie Junction. This link is required as all the central reserve gaps on the existing dual carriageway will be removed at Balmedie.

Due to severance of South Orrock and Orrock House/Boghead accesses an overbridge would be provided to maintain access to the existing A90. Similarly, to the north of the scheme at Foveran and Pitmillan, overbridges would be provided to maintain access to the existing A90.

3.1.2 Sub-Option 2 (Blue)

Sub-option 2 also would begin towards the north edge of Balmedie as Sub-option 1 then veering westwards enabling the existing road to be linked directly into Balmedie. The proposed route would continue northward passing round the east side of the hillock at Orrock House before crossing below the existing road between Pettens and Hill of Menie. At this crossing point the existing road would be maintained by means of an overbridge. The route continues northward running almost parallel to the existing road, past Menie, Newtyle and Foveran before rejoining the existing road corridor at Fountainbleau.

Integration with the local road network commences at the north of Balmedie. As the existing main artery is the existing road it would be linked into Balmedie at the north of the village past "The Bungalow". The existing road would again be maintained through the cutting at Pettens by means of an overbridge. Local access to individual properties would also maintained by a series interlinking minor access roads.

Due to severance of South Orrock and Menie Estate accesses an underpass and overbridge would be provided respectively to maintain access to the existing A90. Similarly to the north of the scheme at Foveran and Pitmillan, overbridges would be provided to maintain access to the existing A90.

3.1.3 Sub-Option 3 (Green)

Sub-option 3 differs slightly from both of the above sub-options by providing initially an online solution. This route would follows the line of the existing road northwards incorporating dualling of the existing single carriageway. The route would continue online until its natural break from the existing alignment at Pettens. From this point the route continues northward parallel to the existing road following the same route as Sub-options 1 and 2.

As the existing single carriageway would be replaced by the dual carriageway at the south of the scheme access would be severed at a number of locations. This proposal would require the provision of a significant number of parallel roads linking the dispersed properties and integration of these with the existing A90. The existing A90 would be maintained by means of an underpass linking it into Balmedie at the north of the village past "The Bungalow".

The B977 Dyce Road would be maintained by the provision of a new link to the Balmedie Junction. This link would be required as all the existing central reserve gaps and direct access would be removed.

Due to severance of the Menie Estate from the existing A90 and an access overbridge would be provided to maintain access into the estate. Similarly to the north of the scheme at Foveran and Pitmillan, overbridges would be provided to maintain access to the existing A90.

3.1.4 Sub-Option 4 (Black)

Sub-option 4 was not taken forward for evaluation in Stage 2 since this sub-option represented only a minor shift in the alignment at the junction with the B9000 (Tipperty). It was considered that the alignment of the northern section of the mainline will be optimised during the development of the preferred option as part of the Stage 3 scheme development process.

3.1.5 Sub-Option 5 (Purple)

Sub-option 5 starts as Sub-option 1 at the north edge of Balmedie. Passing on the west side of the Cock and Bull public house then to the east side of the hillock at Orrock House the route would then veer westwards round the back of the Hill of Menie. The route would continue to curve westwards round the west side of Dambrae and Aikenshill. The route would then veer eastwards before crossing the existing A90 route just south of Foveran and then progress northwards parallel to the existing road as for the other sub-options.

Integration with the local road network would begin at the north of Balmedie. As the existing main artery is the existing road it would be linked into Balmedie at the north of the village past "The Bungalow". The existing road would be realigned at the Newburgh Road junction to take vehicles below the proposed road in an underpass scenario. The existing road to the north of Rashierieve would be tied into the new A975 realignment. Local access to individual properties would be maintained by minor access roads.

The B977 Dyce Road would be maintained by the provision of a new link to the Balmedie Junction. This link would be required as all the existing central reserve gaps on the existing dual carriageway north of this junction would be removed at Balmedie.

Due to severance of South Orrock and Orrock House/Boghead accesses an overbridge would be provided to maintain access to the existing A90. Similarly to the north of the scheme at Foveran and Pitmillan, overbridges would be provided to maintain access to the existing A90.

3.2 Junction Strategy

A junction strategy, involving access to the new dual carriageway at Balmedie, at the A975 route at Rashierieve and at the B9000 at Tipperty has been re-examined using the up-to-date main traffic patterns in the study area. The resulting junction strategy is common to all of the route sub-options considered, as described below.

3.2.1 Balmedie

The community of Balmedie is currently expanding, with further land being allocated for development in the Local Plan for the area (see Section 2.6.12). The significant traffic movements generated by the community result in approximately 70% of the traffic using the southern access junction to head southwards to Aberdeen. The B977 to the west of Balmedie currently provides an alternative route to the congested A90/Anderson Drive leading to Dyce and Aberdeen Airport. The B977 and northern access to Balmedie form a staggered junction on the existing A90.

In the junction strategy process various scenarios for grade separation of junctions at Balmedie were considered:

full junction to the south of Balmedie;
full junction to the north of Balmedie;
half junction to the south of Balmedie and half junction to the north of Balmedie;
full junction to the south of Balmedie and half junction to the north of Balmedie; and
full junction to the south of Balmedie and full junction to the north of Balmedie.

For each of the scenarios an outline layout was prepared, traffic flows generated and a comparative cost-benefit analysis undertaken. This process indicated that a full junction to the south would be the most effective solution.

3.2.2 Newburgh Road/ Tipperty

The A975 provides the main link between Aberdeen City and the coastal settlements of Newburgh and Cruden Bay. The A975 links with the A90 at Rashierieve, midway between Balmedie and Tipperty.

The B9000 routes east-west between Newburgh and Pitmedden and crosses the A90 to the south of Tipperty. A grade separated junction at this location would cater for both existing turning traffic and also traffic from Tipperty.

In the junction strategy process various scenarios for grade separated junctions were considered:

half junction at the A975 and full junction at Tipperty;
half junction at the A975 and half junction at Tipperty; and
no junction at the A975 and full junction at Tipperty

For each of the scenarios an outline layout was prepared, traffic flows generated and a comparative cost-benefit analysis undertaken. This process indicated that a half junction at the A975 Newburgh Road and a half junction at Tipperty would be the most effective solution.

3.3 Public Exhibition

A public exhibition was held in Balmedie in June 2006 to seek public viewpoints on the sub-options (see Section 1.8). This is reported in Route Options Public Exhibition Report dated August 2006. The feedback given at the exhibition led to the refinement of several aspects of each sub-option as follows:

on Sub-options 1,2 and 5 realignment of the existing A90 past "The Bungalow" at Balmedie;
on Sub-option 5 relocation of A975 Newburgh Road Junction to the north to reduce potential impact on properties at Aikenshill and Kirkhill;
Sub-options 1, 2 and 3 moved slightly east at the A975 thus reducing the impact on properties Newtyle and Southlea;
relocation of the overbridges at Orrock House and Boghead (Sub-options 1, 2 and 5); and
B9000 passes below proposed mainline at Tipperty (all sub-options).

The engineering solutions of these refinements are shown in Figures 3.6 to 3.10.

From questionnaire responses the public’s opinion on preferred route choice was gauged. In summary these findings were:

The majority of interest in the scheme was from the local community with 78% of comments received for people within 1km of the route options;
From all the responses received the most favoured scheme is Sub-option 5, chosen by 42 of the respondents and Sub-option 1 being the least favoured at 10;
In analysis of local interest it was found that Sub-option 5 was favoured at 34% with Sub-option 1 being the least favoured at 6% of the respondents analysed;
Regional interest showed Sub-option 3 to be the most favoured option, although all sub-options scored closely;
Local interest saw residents on the east of the existing A90 favouring Sub-option 5;
Local residents to the west of the existing A90 were more split in their preferences with Sub-option 2 being favoured, closely followed by Sub-option 3; and
Support from interest groups on both sides of the existing route saw greater support AGAINST an easterly route over the support AGAINST a westerly route.

From the analysis undertaken it was seen that the overall respondent’s preference was for sub-option 5. From local interest the highest support was for sub-option 5, which outweighs the support for sub-option 2 which was then closely followed by sub-option 3. Sub-option 1 was recognised as the least preferred.

3.4 Cost Estimates

A breakdown of the cost estimates for each Sub-option is shown in Table 3.1 below.

	Sub-option 1	Sub-option 2	Sub-option 3	Sub-option 5
Works:
Pavement	£10,308,000	£10,275,000	£10,227,000	£10,246,000
Earthworks	£8,198,000	£8,166,000	£7,871,000	£5,691,000
Structures	£7,168,000	£7,188,000	£7,184,000	£7,108,000
Others	£5,468,000	£5,352,000	£5,480,000	£5,285,000
Total	£31,142,000	£30,981,000	£30,762,000	£28,329,000
Third Parties
Public Utilities	£580,000	£580,000	£1,000,000	£580,000
Contract Costs
Works	£31,142,000	£30,981,000	£30,762,000	£28,329,000
Third Parties	£580,000	£580,000	£1,000,000	£580,000
Preliminaries	£2,037,000	£2,025,000	£2,010,000	£1,840,000
Contingencies	£3,376,000	£3,359,000	£3,377,000	£3,075,000
Total	£37,135,000	£36,945,000	£37,150,000	£33,824,000
Direct Costs:
Land Acquisition	£680,000	£664,000	£645,000	£670,000
Contingencies	£68,000	£66,000	£64,000	£67,000
Preparation & Admin	£4,160,000	£4,137,000	£4,157,000	£3,794,000
Total	£4,908,000	£4,867,000	£4,867,000	£4,531,000
Scheme Costs
Contract	£37,135,000	£36,945,000	£37,150,000	£33,824,000
Direct	£4,908,000	£4,867,000	£4,867,000	£4,531,000
Total (excl. VAT)	£42,043,000	£41,812,000	£42,017,000	£38,354,000

Table 3.1: Scheme Cost Estimates for Each Sub-option

The table indicates that Sub-option 5 is the least expensive of the options under consideration by approximately £3.5M (excluding VAT). This is primarily a consequence of the earthworks having more balanced quantities of cut and fill material which results in significantly less material required to be disposed of off-site.