2.1 General

This section of the report describes the existing A2 within the limits of Phase 1 of the Scheme. The extent of Phase 1 and the location of existing features are shown on Figure A1.2 in Appendix 1. This figure includes chainages at 500m intervals. The chainage value (CH) is a system for referencing specific points along the route and will be used throughout this report. Phase 1 starts at CH200 and ends at CH4300.

2.1 General

Between the junction with the M25/A282 and the junction with the M2, the A2 is predominantly a dual three lane all-purpose carriageway with hardshoulders. A 2.1km section of the coast bound carriageway between the Bean Junction coast bound entry slip road and Pepperhill Junction (CH1800 to CH3900) was widened to four lanes, in 1998, under a Section 278 Agreement (Highways Act) as part of the Bluewater development scheme.

At the western end of Phase 1, the Bean Junction connects the B255 to the A2. This junction serves the Bluewater development to the north and Bean village to the south. Access to the A2 in the coast bound direction from Bean junction is via the A296 which joins the A2 at the Swanscombe Footbridge where the coast bound carriageway becomes four lanes wide. At the eastern end of Phase 1, the Pepperhill Junction serves the B262 to the south and the A2260 to the north.

2.1 General

2.2 Mainline Layout

2.2.1 General

The existing layout and longitudinal section of the A2 between Bean Junction and Pepperhill Junction is shown on Figures A2.1 to A2.3 in Appendix 2.

At Bean Junction the A2 passes under Bean Road overbridge and heads in an easterly direction towards the coast, climbing gently to a high point at Swanscombe Footbridge. Between this high point (73m above sea level) and the low point at the River Ebbsfleet (11m above sea level), there is a relatively steep grade (maximum 4.2%). Near the bottom of this grade the A2 passes over Park Corner Road. To the east of this point there is a sharp horizontal curve which takes the A2 in a south easterly direction as it climbs again and passes under the Pepperhill overbridge.

2.2.2 Coast Bound Carriageway

At the west end of the Scheme, the coast bound 3 lane carriageway has a shallow downhill grade on the approach to Bean junction where there is an exit slip road. Bean Junction is located on a long vertical sag curve and a right hand horizontal curve. The low point of the sag curve is located where the carriageway passes under the Bean Road overbridge. The hardshoulder has been discontinued through the overbridge for a distance of 230m in order to accommodate a concrete barrier which protects the bridge piers.

Beyond Bean Junction the alignment turns through a large left hand curve and heads up a shallow grade (1.35%) towards Swanscombe Footbridge where there is a tight crest curve. At this point the A296 merges with the A2 (Swanscombe merge). This is the coast bound entry slip road from Bean Junction. The merge has two lanes, one of which merges with the mainline just before the footbridge and the other continues as a lane gain to form the fourth lane. Through the Swanscombe Footbridge there are reduced width lanes and a discontinuous hardshoulder for a distance of 120m; these having been introduced when the fourth lane was added in 1998.

The alignment continues as a 4 lane carriageway with a 2.5km long straight which starts just before the Swanscombe merge and heads downhill with a grade that starts at 3.8% and steepens to 4.2%. At the end of this straight there is a tight right hand curve (840m radius) which starts just after Park Corner underbridge. There are reduced width lanes and a discontinuous hardshoulder across the bridge, which were introduced to accommodate the fourth lane in 1998. On the east side of the bridge there is an exit slip road which serves a petrol filling station, the Springfield Nursery and private residential properties and connects to the Pepperhill Junction via a narrow link road. Beyond the exit the hardshoulder begins again but after a distance of only 150m it is hatched out. At this point the fourth lane is marked as a lane drop for traffic exiting at Pepperhill.

The Pepperhill exit slip road starts with a single lane but the link road from the filling station joins it to form a second lane. Both lanes continue to the signalised junction with the A2260 which crosses the Pepperhill overbridge. Beyond the Pepperhill exit slip road, the mainline has three lanes plus a hardshoulder, which continue gently up hill with a straight alignment through Pepperhill Junction where Phase 1 ends.

2.2.3 London Bound Carriageway

At the eastern end of Phase 1, there is a single lane entry slip road which passes through the Pepperhill overbridge together with the 3 lane main carriageway. The alignment then turns sharply through a left hand curve (840m radius) and starts ascending the 1.5km grade up to Swanscombe Footbridge. This grade starts at 4.2% and slackens off to 3.8% before reaching the tight crest curve at the footbridge. Beneath the Swanscombe Footbridge the hardshoulder is discontinued for a distance of 120m.

Beyond the crest at the Swanscombe Footbridge the alignment has a gentle right hand curve and a shallow downhill grade of 1.35%. At Bean Junction there is a 2 lane exit slip road where the mainline alignment curves to the left and there is a vertical sag curve as it passes under Bean Road overbridge. The hardshoulder has been discontinued through the bridge in order to accommodate a concrete barrier which protects the bridge piers. Beyond the bridge the alignment gently rises as it continues on the left hand curve and there is a two lane entry slip road with a ghost island arrangement.

2.2 Mainline Layout

2.3 Junctions

2.3.1 Bean Junction

Bean Junction was re-modelled in 1998 as part of the Bluewater development. The improvements included the addition of the two roundabouts and realignment of the slip roads. The arrangement of the exit slip roads comply with current highway standards as does the London bound entry slip. The coast bound entry onto the A2 from Bean junction is located at Swanscombe Footbridge and is accessed via the A296. This slip road has a sub-standard arrangement. The merge has standard lengths for the nosing, ghost island and tapers but the taper of the nosing is very sharp (1 in 6.5), this is a departure from the standard taper of 1:30. This large entry angle means that drivers in the right hand merging lane of the slip road are unable to see the mainline traffic until they reach the end of the nosing. The problem is exacerbated by the curvature of the ghost island which causes the merge taper to narrow sooner than with a standard taper.

2.3.2 Park Corner Road/Southfleet Road

There is a minor exit from the London bound carriageway which provides access to Park Corner Road although it is signed "access only" and there are no direction signs. This slip road has a sub-standard arrangement.

To the east of Southfleet Road there is a Petrol Filling Station (PFS) for which there is a direct access from the A2. Traffic exiting the PFS uses a single lane road which connects with the Pepperhill Junction coast bound exit slip road, the traffic then proceeds to Pepperhill Junction in order to rejoin the A2. This route is also used by traffic wishing to join the A2 (coast bound) from Southfleet Road.

Immediately to the west of Southfleet Road there is an access road from the A2 coast bound carriageway serving the Northfleet West Grid Sub Station. However, this access is not usable by A2 traffic because it has been blocked off with safety fencing.

2.3.3 Pepperhill Junction

On the coast bound carriageway there is a lane drop at the Pepperhill single lane exit slip road beyond which there are three lanes that continue through the junction. The coast bound entry slip is a single lane with a standard parallel merge. These slip roads connect to the A2260 Hall Road via a signalised junction.

The layout of the London bound exit and entry slip roads do not comply with current standards as detailed in Section 5.1.1. These slip roads connect to the local roads via a roundabout.

2.3 Junctions

2.4 Traffic Flows

Traffic surveys were undertaken in March /April 2000 to obtain actual observed traffic information on the A2 and the surrounding network, which consisted of the following:

Traffic information was also collected using Automatic Traffic Counts on the M25, M20, M2, A2 and the Dartford Crossing.

The area road network is a combination of urban, inter-urban and rural while the A2 itself is inter-urban in character. The A2 network in the area operates at or close to its capacity during peak traffic periods. Journey time surveys indicate that during peak periods there can be substantial variations in journey times as a result of traffic congestion. The traffic information collected shows that there is a distinct tidal movement of traffic towards London in the morning peak period and away from London in the evening peak period.

Two-way existing traffic volumes on the A2 between Bean Junction and Pepperhill amount to around 117,000 Annual Average Daily Traffic (AADT). Approximately 12% of the flow consisted of heavy goods vehicles. The two-way morning and evening peak hour flows along the same section were approximately 9,100 vehicles per hour and 8,900 vehicles per hour respectively. This is illustrated in Figure A5.1 in Appendix 5.

From the traffic surveys analysis it is clear that queuing regularly occurs at key junctions, such as Bean Junction and M25 Junction 2 during the AM and PM peaks. Queuing gets worse when incidents occur on the road network.

On the London bound carriageway there is an uphill gradient of approximately 4%. The effect of this is to exacerbate congestion because of the slow moving heavy goods vehicles restricting carriageway capacity.

2.4 Traffic Flows

2.5 Engineering Standards

The A2 was originally constructed as a three lane dual carriageway in the mid 1960's. In the subsequent decades various improvements have been made, including the addition of hardshoulders. The standard of the existing carriageway and junctions is generally in accordance with current highway design standards contained in the Design Manual for Roads and Bridges (DMRB). However, there are features such as restricted stopping sight distance (SSD), narrow lanes and sub-standard slip road arrangements which, in some locations, are considered to be departures from current standards. Most of these departures would be retained within the proposed scheme and are described in Section 5.1.1.

2.5 Engineering Standards

2.6 Highway Features

2.6.1 Safety Fencing and Barriers

The existing central reserve has safety fencing throughout the length of Phase 1. There is also safety fencing located in the verges in most locations which protects drivers from hazards such as high embankments, lighting columns and signs.

At Bean Road overbridge and Swanscombe Footbridge there are concrete safety barriers which prevent collision with these structures.

2.6.2 Drainage

The existing drainage for the A2 consists of gullies connected to a piped system that drains to four discharge points which are shown on Figure A6.1 in Appendix 6. Discharge points are a highway drainage pond located at Bean Junction, soakaways at Sandy Lane subway and Swanscombe slip road and an outfall into the River Ebbsfleet.

Pollution prevention measures, such as interceptors or spillage containment devices, are not installed at the discharge points.

2.6.3 Signing

The directional signing on the A2 consists mostly of map type signs located in the verge. However, the coast bound carriageway between Swanscombe Footbridge and Pepperhill Junction has three gantry mounted direction signs that were installed when this section was widened to four lanes in 1998.

2.6.4 Communications

Emergency telephones are currently provided on both carriageways of the A2 between Bean and Pepperhill at intervals of 1 - 1.5 km. These telephones allow motorists to communicate with staff in a police control office at Maidstone.

There is one existing enhanced message sign (EMS) mounted on a cantilever structure located in the verge on the London bound carriageway.

Vehicle detector loops are installed in the existing carriageways in the vicinity of Bean Junction. Data from these loops is relayed to the police control office at Maidstone. This data is used by a wide area traffic monitoring and control system covering main roads in the North Kent area.

2.6.5 Lighting

The A2 is currently lit throughout the area of the Phase 1 works by way of 400 Watt, high pressure sodium lanterns mounted on 15 metre lighting columns. These are generally located along each verge at the rear of the hard shoulder, although at Bean Junction the lighting is located in the central reserve. The spacing between lighting columns ranges from 46m to 50m. Existing lanterns are fitted with flat glass covers, but at some locations, the column bracket arms are inclined by up to 15 to direct the lamp output towards the central reservation. This can lead to some light being emitted above the horizontal, which is wasteful and a source of light pollution.

All existing lighting is controlled by photocells which switch lights on at dusk and off at dawn. The photocells also switch the lighting during the day if the level of daylight is low.

Lighting equipment currently installed in the Sandy Lane subway is in a poor condition.

2.6 Highway Features

2.7 Structures

Since the original construction of the structures on this section of the A2 the design standards have changed but all the structures have been assessed for current assessment loading standards under the Highways Agency 15-year rehabilitation programme. The 15 year programme was announced in 1987 and includes works to enable all structures to carry lorries up to the EC limits of 40 tonnes (gross) and 11.5 tonne drive axles. The programme also includes works relating to safety and durability of the structures.

All the structures on this section of the A2 are maintained by WS Atkins on behalf of the Highways Agency. They are subject to regular inspections and routine maintenance as required by the Highways Agency's Trunk Road Maintenance Manual (Vol 2 part 2).

Hyder Consulting have carried out an inspection of all the structures. Previous assessments have been reviewed and additional assessments have been carried out as required to verify the load capacity of the structures in accordance with current design standards.

2.7.1 Bean Road Overbridge (CH600 - Figure A2.1)

Bean Road Overbridge is a 3 span continuous overbridge that carries the B255 Bean Lane over the existing A2. The deck is an insitu voided post-tensioned concrete slab deck supported on bank seats and concrete columns, the latter being located in the verge and protected from vehicle impact by vertical concrete barriers.

A ground anchored retaining wall was constructed at the southern abutment to accommodate the realignment of the slip road through the side span in 1998.

2.7.2 Sandy Lane Subway (CH1340 - Figure A2.1)

Sandy Lane Subway is a single span rectangular box structure that carries the existing A2 (dual three-lane carriageway with hardshoulders) over Sandy Lane at approximately 26 degrees of skew. The structural form of the subway comprises a simply supported, solid reinforced concrete deck slab supported on mass concrete walls that are pinned at foundation level. Parallel rectangular wingwalls form the vertical legs to discrete reinforced concrete portal frames at both ends of the subway.

2.7.3 Swanscombe Footbridge (CH1830 - Figure A2.2)

Swanscombe Footbridge has a Grade II listed status, having been listed in 1997. The structure comprises a three pinned post-tensioned parabolic arch with post-tensioned cantilevered side spans. Abutments are buried in the cutting slopes and support the arch via concrete hinges buried just beneath the cutting slope. The abutments also support the ends of the cantilevers on rubber bearings. Vertical concrete barriers protect the piers from vehicle collision loading.

2.7.4 Northfleet Retaining Wall (CH2500)

This retaining wall has been amended from its original form to accommodate the addition of the fourth coast bound lane in 1998. The wall measures nearly 150metres long and was constructed using 600mm diameter contiguous bored concrete piles with the pile capping approximately level with the top of the carriageway, and approximately 1m above the adjacent footpath level. However, from site inspections the pile capping is now no longer visible either having been demolished down to a level beneath the widened carriageway or buried by the amended soil slopes.

2.7.5 Park Corner Underbridge (CH3200 - Figure A2.3)

Park Corner Underbridge is a single span, twin deck concrete bridge carrying four coast bound lanes and three London bound lanes (plus a hardshoulder) over the B259 at a skew angle of approximately 17 degrees. Deck construction comprises longitudinal precast concrete I beams and transverse insitu diaphragms acting compositely with an insitu concrete deck slab. Beams and diaphragms are post- tensioned and are supported on piled counterfort type abutments.

2.7.6 CEGB Tunnels (CH4100 - Figure A2.2)

The original horizontal twin service tunnels were constructed at an approximate depth of six metres below the carriageway level of the A2 and had vertical access shafts at each end sited outside the highway boundary. Their depth however was not sufficient to pass beneath the new CTRL construction to be built adjacent to the A2 at this point and they were replaced in 1998 by two new service tunnels constructed and commissioned alongside the original ones. These will pass beneath the new CTRL cut and cover tunnel construction at an approximate depth of 15m below carriageway level. The original tunnels were abandoned and filled in with foamed concrete.

2.7.7 Pepperhill Overbridge (CH4200 - Figure A2.3)

Pepperhill Lane Overbridge, is a four span bridge carrying the A2260 Hall Road and adjacent footpaths over the A2. Each of the spans are simply supported and comprise precast post-tensioned concrete beams with transverse post-tensioned diaphragms and an insitu concrete deck slab. The substructure comprises reinforced concrete spill-through abutments and with three-span frame piers hinged at the top and bottom. The piers are located in the verges and the central reserve. The footpaths across the bridge are protected from accidental wheel loading by temporary bollards at the kerb.

2.7 Structures

2.8 Ground Conditions

2.8.1 Geology and Earthworks

Published geological maps and memoirs and site investigation records indicate the section of the A2 under consideration to be underlain by the sequence of materials shown in Table 2.1. A brief description of the geology of the site is given in Volume 1 of the Environmental Statement.

Table 2.1 Geological Sequence

Table 2.1 Geological Sequence

The earthworks slopes along the A2 have been modified several times since the original construction to facilitate widening that has taken place since then. Cut slopes along the Phase 1 section have been formed in London Clay, Lambeth Group deposits and Thanet Sand. The slopes are generally formed at a grade of 1 vertical to 2 horizontal and appear reasonably stable. Embankment slopes similarly have been formed at 1 vertical to 2 horizontal and appear reasonably stable. Persistent instabilities of the embankment slope adjacent to the Northfleet Substation occurred during the 1970s and 1980s. However the north-facing slope was widened and stabilised during the 1990s.

2.8.2 Surface Water

Surface water features include a highway drainage pond adjacent to the coast bound carriageway at CH700 near Bean Junction and a further pond approximately 400m south of Bean Junction. A surface drain flows northwards towards the south side of the carriageway at CH1550. There are also lakes around Swanscombe, located several hundred metres to the north of the A2.

The only watercourse in the study area is the River Ebbsfleet. It arises from a spring approximately 50m north of the A2 carriageway at Springhead. From here the river flows northwards and discharges into the River Thames at Northfleet.

There are no surface water abstraction points for public water or any other use within 1km of Phase 1.

2.8.3 Groundwater

The Environment Agency (EA) has a duty to monitor and protect the quality of groundwater and to conserve its use for water resources as set out in their Policy and Practice for the Protection of Groundwater (1998). This document uses a series of vulnerability and source protection zone maps.

Groundwater vulnerability depends upon the presence, depth and nature of the overlying soil, drift and strata and is defined in terms of the aquifer and soils. The London Clay is a non-aquifer; the Thanet Sands are a minor aquifer and the Chalk is a major aquifer. Soils ranging from high to intermediate leaching potential are present along the route.

The A2 route between Bean Junction and Pepperhill Junction is underlain in parts by Chalk deposits, the principal aquifer in south-east England. The water table in this aquifer is generally tens of metres below the level of the western section of Phase1. The distance between road level and water table becomes a minimum of approximately 10m at CH4000 near the River Ebbsfleet.

Eight groundwater abstraction licences exist within 1km of Phase 1 and include a public water supply at Southfleet and industrial or agricultural supplies. The EA policy protects abstractions by defining Protection Zones. The road passes across Zone 1 (inner), Zone 2 (outer) and Zone 3 (catchment) Protection Zones as shown on Figure A6.1 in Appendix 6.

There are existing discharges to soakaways in Source Protection Zone 1 (Bean Junction Soakaway), Zone 2 (Sandy Lane) and Zone 3 (Swanscombe Slip Road). It should be noted however that the thickness of the unsaturated zone between the base of the soakaway and the existing level of the groundwater is more than 50m, providing some protection to the groundwater.

Groundwater protection and mitigation measures are covered in more detail in the Environmental Statement.

2.8 Ground Conditions