4. Further Assessment Stage

The following chapters of the report summarise the design development and assessment that was undertaken in the period from the sifting workshop in March to May 2008.

Following the sifting workshop, the route corridor options carried forward for further assessment are as follows:

Northern Route Corridor Options

North Corridor Option 1 – An online upgrade of the existing A90/M90 route corridor between Ferrytoll Junction and Halbeath Interchange.
North Corridor Option 2 – An offline scheme providing a new mainline carriageway between the proposed replacement bridge and Halbeath Interchange.
North Corridor Option 3 – A combined option requiring the online upgrade of the A90 between Ferrytoll Junction and Admiralty Junction with a new section of offline carriageway being provided between Admiralty Junction and Halbeath Interchange.

Southern Route Corridor Options

South Corridor Option 1 – A short offline section of new carriageway connecting the proposed replacement bridge to the A90 south of Echline Junction.
South Corridor Option 2 – A new offline carriageway connecting the proposed replacement bridge to the M9 north of Winchburgh.
South Corridor Option 3 – A new offline carriageway connecting the proposed replacement bridge to the M9 Spur northeast of M9 Junction 1a.
South Corridor Option 4A – A combination of South Corridor Options 1 and 2 providing direct connections to the A90 and the M9.

In the assessment of the seven mainline route corridor options consideration was given to engineering and transportation issues and environmental impact. The further design development enabled the corridors to be described and assessed in more detail. Indicative junction layouts were also considered to ensure that access can be provided/maintained/improved between the proposed mainline and local/national routes.