2 Existing Roads Infrastructure Conditions 2.1 Forth Road Bridge 2.2 Existing Road Network - North of Firth of Forth 2.3 Existing Road Network - South of Firth of Forth

2 Existing Roads Infrastructure Conditions

2.1 Forth Road Bridge

2.1.1 The existing Forth Road Bridge forms a key link in Scotland’s transport network, providing a strategic connection between the north of Scotland and the central belt through its connection of the M90 to the M9 via the A90 and M9 Spur. The existence of the bridge is also key to the east of Scotland economy, providing a vital connection between Edinburgh, the Lothians and Fife. The roads infrastructure connections associated with the Forth Road Bridge are shown in Figure 2.1 and Figure 2.2 (Volume 2).

2.1.2 Operated by the Forth Estuary Transport Authority (FETA), the Forth Road Bridge opened in 1964. Throughout its life, the bridge has seen a marked increase in traffic growth and now carries in excess of 65,000 vehicles per day, equating to 70% of all cross-Forth traffic (Kincardine Bridge and the Forth Rail Bridge providing alternative routes and means of travel).

2.1.3 Although well maintained throughout its 44 year existence, the bridge now shows signs of deterioration, climatic influences, weather and increased traffic volumes all having an effect. Several major maintenance projects have been undertaken over the years to replace, strengthen and improve elements of the structure in an attempt to mitigate against deterioration, traffic loading, shipping impact and design code changes.

2.1.4 The work undertaken has included the strengthening of viaduct box girders, wind bracing and main towers, hanger replacement and the construction of pier defences. Maintenance of the main suspension cables has also been undertaken, with regular external inspections having been carried out.

2.1.5 The first internal inspection of the main cables was undertaken in 2004, significant corrosion being discovered with the loss of strength being interpreted at between 8% and 10%. Predictions indicate that unchecked, the rate of corrosion experienced could lead to the factor of safety falling below the acceptable value of 2.0 by 2014. Live load restrictions would be necessary to cater for such a situation. HGV restrictions would be implemented in the first instance with further restrictions being required within five years to extend the life of the bridge.

2.1.6 In assessing the current rate of deterioration, acoustic monitoring equipment has been installed on the bridge, capable of detecting the failure of cable strands.

2.1.7 In addition, FETA in association with their consultants Faber Maunsell and Weidlinger Associates are now attempting to arrest the deterioration of the main cables through the implementation of a dehumidification system. The system will be completed in 2009. Its success will not be known until 2012 when a further inspection will be carried out.

2.1.8 As part of the second inspection undertaken during 2008 the main cables were deemed to have lost 10% of their strength. FETA and their consultants are optimistic that the rate of deterioration is slower than first thought, with load restrictions considered now likely to be deferred until sometime between 2017 and 2021.

2.2 Existing Road Network - North of Firth of Forth

2.2.1 The A90/M90 forms a strategic link between the Forth Road Bridge and the north, providing access to the substantial population centres of Dunfermline, Perth, Dundee, Aberdeen and Inverness (via the A9). Figure 2.1 (Volume 2) details the existing road network north of the Firth of Forth on approach to the existing bridge.

2.2.2 Departing the Forth Road Bridge northbound, the route is designated as the A90, a dual two lane all purpose road with discontinuous hard shoulders. Passing to the west of North Queensferry, the route descends through Ferry Hills into a valley where the grade separated Ferrytoll Junction provides access to Rosyth, Rosyth Dockyard, Inverkeithing and North Queensferry via Ferry Toll Road, the B980 and B981. Also providing access and egress to Ferrytoll Park and Ride, the junction is situated at existing ground level, the A90 being carried on structure above.

2.2.3 Continuing north, the A90 passes to the east of Castlandhill, significant rock cuttings being associated with the route through this section. Cresting in the vicinity of Dunfermline Wynd Overbridge, the route then descends toward Admiralty Junction. Through this section, a hard shoulder is provided to the northbound carriageway. The opposing southbound hard shoulder is utilised as an auxiliary lane providing access to North Queensferry, Inverkeithing and Ferrytoll Park and Ride via Ferrytoll Junction.

2.2.4 The grade separated Admiralty Junction, provides further access to Rosyth and Inverkeithing from the A90 via the A985 and A921. Utilising a roundabout to maintain traffic movements, the junction is situated beneath the mainline carriageway, the A90 being carried on structure.

2.2.5 North of Admiralty Junction, the route classification changes from dual two lane all purpose road to dual two lane motorway with the implementation of the M90. From a low point west of Belleknowes Industrial Estate, the route climbs out of a valley on viaduct towards Masterton Junction, where free flow links provide access to Rosyth and Dunfermline via the A823(M). The Fife Circle Railway line is also located in the area, passing beneath the viaduct on an east to west bearing.

2.2.6 Beyond Masterton, the route continues to rise passing to the southeast of Middlebank on a north easterly orientation. Continuing to climb through an area of predominant farmland, the route sweeps north towards Halbeath Interchange where access is provided to east Fife via the A92 and Dunfermline via the A907.

Design Standards

2.2.7 The geometry of the existing A90/M90 does not conform to the current design standards laid out in the DMRB. Of particular concern is the section of carriageway between Admiralty and Masterton where traffic merging and diverging between the junctions has a very short weaving distance within which to manoeuvre. Additionally the horizontal geometry of the mainline contains substandard elements in proximity to Admiralty Junction and Masterton Junction, horizontal radii of up to two design speed steps below desirable minimum being experienced.

2.2.8 Road Pavement

2.2.9 Following an initial review of available pavement information, the predominant pavement type on the trunk road network has been found to be of flexible composite construction, where a bituminous layer of material overlays a cementitious base.

2.2.10 The surface condition of the pavement has been found to be performing generally well, the lengths of carriageway requiring improvement coinciding with the areas that require strengthening through an overlay of bituminous material.

Structures

2.2.11 The structures associated with the existing A90/M90 route corridor are detailed in the following paragraphs. The location of each is presented in Figure 4.5 (Volume 2).

2.2.12 The structures referencing system used in this report has been developed in tandem with the optioneering work undertaken to date on the Forth Replacement Crossing Project. It is a stand alone project based referencing system which does not correlate with any existing system that might be in use by Transport Scotland or BEAR Scotland Ltd.

Structures 177-4 and 177-5

2.2.13 Structures 177-4 and 177-5 carry the A90 over Ferrytoll Junction. Both are single span structures with maximum span lengths of 11.89 metres with no skew. They are both insitu reinforced concrete portal frame structures of integral construction founded on spread footings.

Structures 177-10, 177-11 and 177-12

2.2.14 Structure 177-10 is the Ferrytoll railway tunnel located beneath the A90 at Ferrytoll Junction. It is a single span structure with an overall length of approximately 95 metres comprising a maximum span of 4.95 metres at a varying skew.

2.2.15 Structure 177-11 carries the B980 over the Inverkeithing South Junction – Rosyth Dockyard Branch Line Railway close to the entrance/exit to the tunnel. It is a single span structure with a maximum span of 5.88 metres at a skew of 23°.

2.2.16 Structures 177-10 and 177-11 are concrete arch structures of integral construction. Structure 177-10 is founded on spread footings, however the foundation type for Structure 177-11 is unknown.

2.2.17 Structure 177-12 is located adjacent to structure 177-11. It is a single span structure with a span of 20.5 metres at a skew of 23°. It is a precast beam and slab structure of integral construction founded on spread footings and was built circa 2006.

Structure 170-1

2.2.18 Structure 170-1, Dunfermline Wynd Overbridge, carries Dunfermline Wynd over the A90. It is a three span structure with an overall length of 71.8 metres between abutment centres with a maximum span length of 32.2 metres. It comprises a haunched concrete deck with a voided suspended main span. The piers are founded on spread footings and the abutments on piles.

Structures 182-8 and 182-9

2.2.19 Structures 182-8 and 182-9 are retaining walls at Admiralty Junction on the northwest and southeast sides respectively. The northwest wall has a maximum retained height of 5 metres and an overall length of 86 metres. The southeast wall has a maximum retained height of 6 metres and an overall length of 135 metres. Both are of mass concrete construction with masonry facing and are founded on spread footings.

Structures 182-6 and 182-7

2.2.20 Structures 182-6 and 182-7 carry the M90 over Admiralty Junction. Both are single span structures with spans of 15 metres at skews of 30° and 30.5° respectively. Both are reinforced concrete portal frame structures with Structure 182-7 founded on spread footings and Structure 182-6 on bored concrete piles.

Structure 182-5

2.2.21 Structure 182-5 is a concrete arch culvert which carries the Brankholm Burn beneath the M90. It is a single span structure with a clear span of 3.6 metres at a skew of 10°.

Structure 182-1

2.2.22 Structure 182-1, Masterton Viaduct, carries the M90 over the A823 comprising twin decks running parallel to each other in a generally north / south direction. The decks are supported on a common reinforced concrete pier at each intermediate support and on full height abutments at each end.

2.2.23 It is a ten span structure which is approximately 183m long overall and has a span arrangement, running south to north, of 14.9m (over railway), 7 x 18.6m, 19.2m and 18.75m at a skew of 4°.

2.2.24 Generally, the decks comprise of reinforced concrete slabs. However, the southern end span of each deck over the railway consists of steel/concrete filler beam construction comprising steel castellated beams with a precast bottom concrete flange which acts as permanent formwork to concrete infill between and over the beams.

2.2.25 The existing Masterton Viaduct is capable of sustaining 40 tonne assessment loading and accidental vehicle loading in both longitudinal bending and shear. The HB rating of the structure ranges from 20 units based on longitudinal bending to 35 units in shear for the 3 span intermediate sections.

Structure 182-2

2.2.26 Structure 182-2 carries the M90 northbound off slip road to the A823(M) over the Fife Circle Railway Line. It is a single span structure with a span of approximately 50 metres at a skew of 50°.

Structure 182-13

2.2.27 Structure 182-13 carries the B981 over Inverkeithing East Railway Junction.

Structure 182-14

2.2.28 Structure 182-14 is located beneath the A823(M) on the approach to Masterton Junction.

Structures 182-3 and 182-4

2.2.29 Structure 182-3 carries the A823(M) to M90 southbound slip road over the M90. Structure 182-4 carries Masterton Road over the M90. Both are single span structures, Structure 182-3 having a span of 36 metres at a varying skew and Structure 182-4 having a span of 38.4 metres. Both structures are reinforced concrete portal frame structures founded on spread footings.

Structure 171-2

2.2.30 Structure 171-2, Duloch Overbridge, carries the B916 Aberdour Road over the M90. It is a two span structure with an overall skew length of 30.9 metres (between abutment centres) with a maximum span length of 14.9 metres at a skew of 10°. It is a variable depth concrete slab structure founded on a reinforced leaf pier and full height abutments, all founded on spread footings.

Structure 000-1

2.2.31 Structure 000-1, Calais Muir Overbridge, carries a side road over the M90 close to Calais Muir Wood. It is a four span structure with an overall skew length of 52.3 metres (between abutment centres) with a maximum span length of 14.8 metres. It is an insitu reinforced concrete slab structure founded on leaf piers and bankseat abutments, all founded on piles.

Existing Traffic Patterns

2.2.32 The principle links north of the Firth of Forth are:

  • M90/A90 Inverkeithing – Fraserburgh Trunk Road;
  • A921 forming an east - west route between Kirkcaldy and Admiralty Junction (M90 Junction 1);
  • A985 Kincardine – Rosyth Trunk Road forming an east - west route between Admirality Junction (M90 Junction 1) and Kincardine;
  • A823/A823(M) Pitreavie Spur Trunk Road forming an east - west route between Masterton Junction (M90 Junction 2) and Dunfermline;
  • A907/A92 East Fife Regional Road forming an east - west route between Kirkcaldy and Dunfermline via Halbeath Interchange (M90 Junction 2a/M90 Junction 3).

2.2.33 Annual Average Daily Traffic (AADT) volumes for 2006 at selected points along the M90 north of the Firth of Forth are summarised in Figure 2.3 (Volume 2). This indicates that the most heavily trafficked section of the M90 north of the Firth of Forth is between Masterton (M90 Junction 2) and Admiralty (M90 Junction 1), and that the majority of traffic joining or leaving the M90 within the northern study area does so at the Halbeath Interchange (M90 Junction 2a / M90 Junction 3).

2.2.34 Further evidence of the traffic volumes using the junctions and ramps at M90 Junction 2a and M90 Junction 3 is provided by the 2008 Automatic Traffic Count (ATC) data provided by Transport Scotland, as summarised in Table 2.1. Of particular note is the tidal traffic flow to/from the A92 and east Fife via M90 Junction 2a.

Table 2.1: M90 Link Flows (2008) – Northern Study Area

Count Location

Direction

Time Period

AM (0800-0900)

PM (1700-1800)

Halbeath – A92 ramps (M90 Junction 2a)

NB

400

1000

SB

1200

1100

M90 (south of M90 Junction 2a)

NB

2500

3400

SB

2200

2100

M90 (between Admiralty & Ferrytoll)

NB

2700

3600

SB

2500

2700

Note: Units are total vehicles, to the nearest 100. Data derived from Transport Scotland Automatic Traffic Counters.

2.2.35 As shown in Table 2.1, the southbound AM flow on the A92 at M90 Junction 2a is higher than the equivalent northbound flow of vehicles during the same time period. With tidal traffic flows, which are commonly represented by commuting trips, a reverse of the AM flows is generally found in the PM period. The northbound flow does increase at this location during the PM, however the overall trend is for southbound flows to be higher than northbound flows during both peaks. Elsewhere, southbound flows are broadly similar in both the AM and PM periods, northbound flows being higher in the PM.

Congestion

2.2.36 Congestion is present in the form of southbound queues approaching the Forth Road Bridge, predominantly in the AM peak. This queue can extend for several kilometres in normal conditions. Close spacing of junctions along the road approaching the bridge contributes to the formation and extension of queues in the morning as traffic attempts to join the mainline from Masterton, Admiralty and Ferrytoll Junctions.

Road Accidents

2.2.37 The incidence of road accidents between 2000 and 2007 throughout the northern study area is presented in Figure 2.4 (Volume 2). Accident locations are colour coded to indicate the severity of personal injury. All data is based upon reported road accidents on major road links provided by Fife Council. The accident data covers both the scheme corridor and the main alternative routes.

2.2.38 Whilst there are concentrations of accidents around the junctions on the M90 and A90, the majority of accidents are slight injury accidents. The main concentrations of accidents, in the study area, are in and around Dunfermline town centre, rather than in the scheme corridor or alternative routes. These roads and hence accident rates are not seen as directly relating to the scheme and accident rates in this area are unlikely to be significantly affected by the scheme.

2.2.39 Table 2.2 presents the distribution of reported road accidents by injury severity across the northern study area, compared to the same distribution for Scotland as a whole. This shows the northern study area to have lower than expected fatal injuries, but higher than expected severe injuries. No fatal injuries have been recorded on the M90/A90.

Table 2.2: Accidents by Severity (2000-2007), Northern Study Area (Fife Council)

Severity

Northern Study Area

Scotland

No. of Accidents

Percentage (%)

No. of Accidents

Percentage (%)

Fatal

8

1.2%

2,227

2.0%

Severe

130

19.0%

19,837

17.9%

Slight

546

79.8%

88,810

80.1%

Total

684

100.0%

110,924

100.0%

Note: Scotland-wide data sourced from: ‘Key Road Accident Statistics 2007’ – ‘Table 1: Injury Road Accidents by Severity, 1970-2007’ (2008), The Scottish Government. This includes provisional 2007 data.

2.2.40 Table 2.3 presents recent annual changes in accidents by severity. This shows an increasing trend in the total number of recorded accidents since 2001. Within this trend, however, there are some year-on-year declines in 2002, 2004, and 2005.

Table 2.3: Number of Accidents by Severity (2000-2007), Northern Study Area

Severity

Year

2001

2002

2003

2004

2005

2006

2007

Fatal

1

0

2

1

1

1

2

Severe

15

14

15

24

16

26

20

Slight

56

44

100

85

79

86

96

Total

72

58

117

110

96

113

118

2.3 Existing Road Network - South of Firth of Forth

Features

2.3.1 South of the Forth Road Bridge, the A90 and the M9 Spur form the principle traffic links to Edinburgh and the central Scotland motorway network.

2.3.2 Departing the Forth Road Bridge, the A90 as a dual three lane all purpose road provides access to all routes with local access connectivity to the A8000 and A904 provided through Echline Junction. The junction arrangement itself takes the form of a grade separated roundabout, bridge structures allowing the A90 to pass beneath.

2.3.3 South of Echline Junction, the A90 climbs with existing ground topography towards Scotstoun Junction. The junction, which was opened in conjunction with the M9 Spur Extension in 2007, provides direct access between the Forth Road Bridge and the M9, a lane drop and lane gain arrangement maintaining access to the A90 and the north of Edinburgh.

2.3.4 The M9 Spur, encompassing the M9 Spur Extension, provides a dual two lane motorway between Scotstoun Junction and M9 Junction 1a. Running parallel to the Falkirk-Fife Railway Line between Scotstoun Junction and Humbie Overbridge, the route replaces the A8000 as the principle route between the M9 and the Forth Road Bridge.

2.3.5 In its provision, a number of new structures and culverts have been constructed, crossings being situated at Dolphington Burn, Milton Farm Road and the B800. Existing crossings of the Falkirk – Fife Railway Line and the B9080 have been retained from the original M9 Spur link to the A8000.

2.3.6 The provision of access between the M9 and M9 Spur is facilitated through a free flow junction arrangement at M9 Junction 1a. Providing M9 east facing connectivity only, a loop connects the M9 to the M9 Spur northbound, a simple slip road arrangement providing connectivity between the M9 Spur and the M9 eastbound.

2.3.7 Given the lack of connectivity to the M9 westbound, traffic west of M9 Junction 1a wishing to access the Forth Road Bridge is required to travel via alternative routes, the A904 providing access to Bo’ness and M9 Junction 2 located north of Winchburgh.

2.3.8 Access and egress to/from the west of Edinburgh is provided through Newbridge Roundabout, situated to the south of M9 Junction 1a. A number of key routes converge on this junction, the A8 providing access to the west of Edinburgh, the A89 providing access to West Lothian and the M8 providing access to Glasgow and the A720 Edinburgh City Bypass.

Design Standards

2.3.9 Given the recent upgrades to highways infrastructure south of the Forth Road Bridge, the design standard issues applicable to the route revolve around junction provision to the M9.

2.3.10 The existing M9 Junction 1a loop arrangement providing access to the M9 Spur from the M9 is operated with an advisory 30mph speed limit. Furthermore, the slip road arrangement connecting the M9 Spur to the M9 eastbound is in close proximity to the links associated with Newbridge Roundabout, an auxiliary lane being provided to improve provision for weaving movements.

Road Pavement

2.3.11 Following an initial review of available pavement information, the predominant pavement type on the trunk road network has been found to be of flexible composite construction, where a bituminous layer of material overlays a cementitious base.

2.3.12 The surface condition of the pavement has been found to be performing generally well, the lengths of carriageway requiring improvement coinciding with the areas that require strengthening through an overlay of bituminous material.

Structures

2.3.13 The structures associated with the existing A90/M90 route corridor are detailed in the following paragraphs. The location of each is presented in Figure 4.15 (Volume 2).

Structure 167-9

2.3.14 Structure 167-9 is a culvert carrying the Niddry Burn under the existing M9.

Structure 167-10

2.3.15 Structure 167-10 carries the M9 Spur over the M9. It is a three span structure with a maximum span length of 40 metres with an overall length of 85 metres at a skew of 10°. It is a steel/concrete composite structure founded on spread footings.

Structures 167-8 and 187-8

2.3.16 Structure 167-8 is a twin barrel culvert carrying the M9 Spur to M9 eastbound slip road over the Swine Burn. It is a single span structure with an overall length of 142 metres and headroom clearance of 4.3 metres.

2.3.17 Structure 187-8 is a culvert which carries the M9 Spur over the Dolphington Burn.

Structure 167-5

2.3.18 Structure 167-5 carries the M9 Spur over B9080. It is a single span bridge and has a span of 29 metres with no skew. It is an insitu slab structure founded on spread footings.

Structure 167-7

2.3.19 Structure 167-7 carries the M9 over an existing side road west of M9 Junction 1a. It is a two hinged portal single span structure with a span of 10 metres at a skew of 18°.

Structure 167-11

2.3.20 Structure 167-11, Humbie Railway Bridge, carries the M9 Spur over the Falkirk-Fife Railway Line. It is a single span bridge and has an approximate span of 17 metres at a skew of 40°. It is a prestressed beam and slab structure founded on piles.

Structure 239-11

2.3.21 Structure 239-11 carries the M9 Spur link road over the A90 westbound. This structure was provided as part of the M9 Spur Extension contract and to date no record information has been made available as to its form of construction.

Structure 239-3

2.3.22 Structure 239-3 carries the A8000 over the A90. It is a two span bridge with an overall length of 29.6 metres comprising a maximum span of 14.8 metres at a skew of 20°. It is an insitu slab structure supported on spread footings.

Structure 187-4

2.3.23 Structure 187-4 carries the Echline Junction over the A90. It is a single span structure with a span of 30 metres with no skew. It is an insitu concrete slab structure founded on spread footings.

Existing Traffic Patterns

2.3.24 The principle links south of the Firth of Forth are:

  • A90 between the north of Edinburgh and South Queensferry;
  • M9 Spur (including the recently constructed M9 Spur Extension) between M9 Junction 1a and Scotstoun Junction;
  • M9 Edinburgh – Stirling – Thurso Trunk Road;
  • M8/A8 Edinburgh – Greenock Trunk Road;
  • A8/A89 forming an east - west route between Edinburgh, West Lothian and beyond;
  • A8000 forming a north - south route between South Queensferry and Kirkliston
  • A720 Edinburgh City Bypass;
  • A904 forming an east - west route between Bo’ness and South Queensferry.

2.3.25 2006 Annual Average Daily Traffic (AADT) volumes were obtained from Transport Scotland for key road bridge connections south of the Firth of Forth. These are summarised in Figure 2.5 (Volume 2).

2.3.26 From the above, the following operational trends can be identified:

  • The most heavily trafficked roads directly linked to the Forth Road Bridge within the southern study area are the A90 to/from Edinburgh, and the M9 (south of M9 Junction 1a);
  • 14,400 vehicles per day use the A904 as a means of travelling to/from the west. Approximately double this number (27,000 vehicles) use the M9 to travel to/from the west.

2.3.27 The data presented above represents the 2006 network traffic flows, prior to the opening of the M9 Spur Extension between M9 Junction 1a and the A90 at Scotstoun Junction in 2007. The M9 Spur now provides an alternative to the A8000 for traffic travelling between these points. As shown in Tables 2.4 and 2.5 for the weekday morning and evening peaks respectively, the resulting additional traffic demand on the M9 Spur contributed to a reduction in traffic demand on the A90 between the Forth Road Bridge and Edinburgh. This also includes the effect of removing tolls on the Forth Road Bridge.

Table 2.4: Effect of the M9 Spur Extension on A90 and M9 Spur Traffic Flows (Morning Peak)

Count Year

A90

M9 Spur

Westbound

Eastbound

Northbound

Southbound

2006

1500

1500

900

1200

2008

1300

1400

1400

1300

Total vehicle change

-200

-100

+500

+100

%age change

-13

-7

+56

+8

Note: Morning Peak, 0800-0900 hours. Units are total vehicles, to the nearest 100. Data derived from Transport Scotland Automatic Traffic Counters.

Table 2.5: Effect of the M9 Spur Extension on A90 and M9 Spur Traffic Flows (Evening Peak)

Count Year

A90

M9 Spur

Westbound

Eastbound

Northbound

Southbound

2006

2200

2200

900

1000

2008

1900

1300

1500

1400

Total vehicle change

-300

-900

+600

+400

%age change

-14

-41

+67

+40

Note: Evening Peak, 1700-1800 hours. Units are total vehicles, to the nearest 100. Data derived from Transport Scotland Automatic Traffic Counters.

2.3.28 Current peak hour traffic flows on other selected key links in the southern study area are shown in Table 2.6.

Table 2.6: Link Flows (2008) – Southern Study Area

Count Location

Direction

Time Period

AM (0800-0900)

PM (1700-1800)

M8 (west of Newbridge)

WB

2300

3250

EB

3450

2250

M8 (between Newbridge & Hermiston Gait)

WB

2550

3600

EB

3800

2050

A720 (south of Hermiston Gait)

NB

2400

2300

SB

2600

3050

A720 (between Hermiston Gait & Gogar)

NB

2050

800

SB

1150

2300

A8 (Glasgow Road)

WB

950

950

EB

1250

900

A8 (between Gogar & Edinburgh Airport)

WB

1700

2100

EB

3000

2150

A8 (between Edinburgh Airport & Newbridge)

WB

1500

1750

EB

3150

1550

Note Units are total vehicles, to the nearest 50.

2.3.29 Table 2.6 reveals a tidal pattern of commuting traffic travelling to and from Edinburgh along the M8. Connections between a variety of key destinations other than Edinburgh City Centre (e.g. Edinburgh Airport) via the A8 and A720 Edinburgh City Bypass result in a more complex distribution of traffic demand on these routes.

Congestion

2.3.30 Congestion is present in the form of northbound queues approaching the Forth Road Bridge, predominantly in the PM peak. These queues are largely as a result of 2 lanes from the A90 merging with 2 lanes from the M9 Spur, into 3 lanes and then into 2 lanes as the road passes under Echline Junction. At this point, traffic from Echline merges with the bridge traffic, further adding to the congestion effects. North of the Forth Road Bridge, there is less indication of congestion as traffic travels north.

2.3.31 In the AM period, southbound traffic queues on the M9 Spur. Completion of the M9 Spur has encouraged some southbound traffic to re-route to the M9, from the A90 (to Barnton). This increased traffic regularly forms a queue on the M9 Spur as it approaches M9 Junction 1a. The M9 Spur narrows from 2 lanes to 1 lane as it merges with the motorway and this narrowing of the carriageway contributes to queue formation at this location.

Road Accidents

2.3.32 The locations and severity of road accidents between 2000 and 2007 throughout the southern study area are presented in Figure 2.6 (Volume 2), based on reported accidents data supplied by the City of Edinburgh Council (CEC) and West Lothian Council (WLC). Figure 2.6 illustrates the density of accidents throughout the northern and southern study areas with accident clusters shown in and around a number of key junctions across the network. In the southern study area, these include:

  • M8 Extension/A720 Edinburgh City Bypass, near Hermiston Gait;
  • A8/A720 Edinburgh City Bypass Gogar Roundabout;
  • Maybury traffic signals on the A8;
  • Drum Brae Roundabout (A8, Corstorphine Road);
  • Edinburgh Airport dumb-bell access roundabouts (A8);
  • M9/A8/A89 Newbridge Roundabout;
  • Barnton traffic signals on the A90; and
  • A90/A904 at Echline Junction.

2.3.33 Table 2.7 presents the distribution of reported road accidents by injury severity across the southern study area, compared to the same distribution for Scotland as a whole. This shows that the southern study area has lower than expected fatal and severe injuries, but higher than expected slight injuries.

Table 2.7: Accidents by Severity (2000-2007), Southern Study Area

Severity

Southern Study Area

Scotland

No. of Accidents

Percentage

No. of Accidents

Percentage

Fatal

29

1.2%

2,227

2.0%

Severe

268

10.8%

19,837

17.9%

Slight

2181

88.0%

88,810

80.1%

Total

2478

100.0%

110,924

100.0%

Note: Scotland-wide data sourced from: ‘Key Road Accident Statistics 2007’ – ‘Table 1: Injury Road Accidents by Severity, 1970-2007’ (2008), The Scottish Government. This includes provisional 2007 data.

2.3.34 Southern study area accident statistics are presented by year in Table 2.8. This shows that total accidents declined between 2001 and 2007, although this includes some year-on-year rises in 2003 and 2006.

Table 2.8: Number of Accidents by Severity (2000-2007), Southern Study Area

Severity

Year

2001

2002

2003

2004

2005

2006

2007

Fatal

4

2

4

4

6

6

2

Severe

41

38

37

35

46

41

24

Slight

333

316

320

315

285

307

296

Total

378

356

361

354

337

354

322