LONDON CANTERBURY DOVER TRUNK ROAD A2 BRIDGE BYPASS . DEPARTMENT OF THE ENVIRONMENT * bo} P. A. Bays, G.M., F.I.C.E., M..Mun.E., M.R.T.P.I. A. D. W. Smith, B.Sc.(Eng.), F.I.C.E., F.l.Mun.£., F.lnst.H.£., M.1.S.W.M., Regional Controller (Roads and Transportation), County Surveyor, : ‘ Department of the Environment, Maidstone, a t ‘Guildford. Kent. " Section I 1). 2). 3). 4). 5). 6). The Section IT ld = 2) 3). “Section Tit Section IV Section Vv Section VI Section VII Section VIII APPENDICES II IIL CONTENTS Introduction Early History Existing Conditions Alternative Routes Planning Relationship of Bridge Bypass to Existing and Proposed Network Landscape Works Accident Record General Discription and Site Dimensions Interchanges and Accesses Outline Costs Design Considerations and Standards Ground Conditions and Geology Construction Details Public Utilities and Bodies Bridges Highway Services Main Contractor's Tender and Sub-Contractors Progress Photographs Major Accommodation Works Page WwW MY Pp eB nN 10 10 12 42 13 22 27 BE 36 AG No. wo On aw Fw 10 12 13 14 15 16 17 18 19 20 21 23 24 25 26 27 28 28 30 31 32 DIAGRAMS Title Alternative Routes At Preliminary Report Stages Relationship Between Bridge Bypass and the Existing and Proposed A.2 Network Landscape Re-Contouring Landscape Cross Section Diagram Landscape Cross Section Diagram Landscape Cross Section Diagram Landscape Cross Section Diagram Routes of Bridge Bypass Typical Earthworks Cross Section Bekesbourne Road Cut Typical Earthworks Cross Section - Bridge Down Cut Typical Earthworks Cross Section - @ldharbour Lane Embank- ’ ment Predicted Noise Contours Before Landscape Treatment Vehicles/Average 16 Hrs. Day in August 1970 Geological Long Section - Part : an Geological Long Section - Part II Geological Long Section - Part III Standard Detail for 7.9 metre Construction in Flexible or Composite Materials - In Cutting Standard Detail for 7.9 metre Corstruction in Flexible or Composite Materials - On Embankment Standard Detail for 7. Composite Materials Standard Detail for 7. Composite Materials Typical Ditch Detail metre Construction in Flexible or Detail A 1. metre Construction in Flexible or Detail B io Flexible and Composite Paving Alternative Designs Concrete Paving Alternative Designs Concrete Paving Alternative Designs Warping Joints Standard Details for 8.6 metre Concrete Construction - In Cutting Standard Detail for 8.6 metre Concrete Construction - Cn Embankment Bifron's Park Subway Bekesbourne Road Bridge Patrixbourne Road Bridge Coldharbour Lane Bridge Highland Court Accommodation Bridge y -] 3 Q woo wmWonwu | RPP oe Aw a9 20 23 24 25 30 30 31 a1 31 9 33 a oo 34 a7 38 40 4 ke Pagel SECTION L GENERAL INTRODUCTION 1e Early History The last three decades have seen a dramatic increase in the flow of traffic through Kent to Europe. Coupled with this, the North Kent coastal towns have expanded rapidly during the same periods. As a result, the two main trunk roads in the County of Kent and particularly the A.2, became overloaded. Recognising this, the then Ministry of Transport adopted a policy of progressive improvement of the London-Canterbury- Dover Trunk Road, starting with the construction of the Medway Towns Bypass, M.2, which was opened to traffic in 1961. Since that time, there have been a series of schemes. Bridge Bypass forms one of the later projects in this series along with bypasses for the villages of Boughton and Harbledown. In January, 1967, a meeting between representatives of the Divisional Road Engineer, Rural District Councils and the Kent County Council was held to discuss a policy for improving the London-Canterbury-Dover Trunk Road, A.2, from the eastern end of the Motorway M.2, at Brenley Corner, to the Borough of Dover. Following this meeting, the Divisional Road Engineer outlined a comprehensive plan for improving the A.2, which was to carry out a number of schemes to improve the existing road and to construct bypasses of villages where necessarys Included among the latter was a proposal to construct a bypass of Bridge by the mid-1970's. Ds Existing Conditions The village of Bridge (pepulation 1,225 as at 1971/72 census) lies on the existing A.2 between Canterbury and Dover. The built-up area of the village covers a length of approxi- mately 1.1 miles and the central 0.6 mile length has continuous frontage development on both sides of the road. This section has a 30 mph speed limit and has recently been made the subject of a conservation area. The average existing road width is 7.0 metres and the minimum width is 5.3 metres in the centre of the Viilage. The village lies at the bottom of a valley and the existing highway gradients 0.5 miles east and west of the central area are 7.5% and 526 5% respectively. The village acts as a shopping centre for surrounding smaller villages, giving a shopping population of approximately 2,800; there are twenty shops in the central area, including a supermarket and some congestion is caused by associated private and commercial vehicles. Trunk road traffic, especially heavy lorries, make the environment in the centre of the village unpleasant. The footway width varies, but is as nerrow as 1.2 metres in parts of the central shopping area. Pace 2 —s The figures for a traffic count at Bridge in September 1969 produced an August 16 hr. daily flow of 13,030 vehicles, or 16,430 peceu's. Three projected figures were considered for the design year 1990 and are as follows:- a) Assuming M.20 in use and Channel Tunnel in use, projected daily flow is 15,488 vehicles. b) Assuming no M.20 in use and no Channel Tunnel, projected daily flow is 23,828 vehicles. c) Assuming M20 in use and no Channel Tunnel, projected daily flow is 19,063 vehicles. The percentage of goods vchicles was found to be 162% of weekday traffic, 4% of weekend traffic and 134% of total traffic. The goods vehicle traffic, largely T.I.R.'s, is predominantly generated by the docks at Dover. 36 Alternative Routes Three lines were considered at preliminary report stage, shown on a diagram overleaf. Each route was designed so as to ultimately join the proposed Canterbury Bypass to the north- west and the proposed dual carriageway on the existing A.2 to the south-east as follows:- =a i) Route 'A' (north-east of Bridge) From the Canterbury end the route swung eastwards in cutting under the Bekesbourne Road, descending across Bifron's Park and the Nailbourne Valley and then rose, passing west of Highland Court to rejoin the existing A.2 at Coldharbour Lanee This route was adopted for the scheme. ii) Route 'B' was an improvement of the existing alignment through the village. iii) Route 'C' (south-west of Bridge) From the Canterbury end the route swung west close to Renville Farm and descended into the Nailbourne Valley via Great Pett Farm and then rose through Bourne Park, rejoining the A.2 at Frog Lane, Bishopsbourne. At a later date, other southern routes were investigated in outline detail, including the suggested use of the old Canterbury-Folkestone railway line. It was found that all the southern routes had disadvantages with respect to route planning and access. They were also considered by the Kent County Council Planning Department to be more damaging to the local environment than the proposed northern reute. The northern route was subsequentiy investigated in full detail and the proposals put to a Public Enquiry held in May 1973 and accepted. The Secretary of State for the Environment confirmed the orders in August, 1973. Page 3 A Planning Widening the existing A.2 (Route 'B') was considered the least desirable alternative for the following reasons:- (i) There would have been an unacceptable amount of demolition to private propérty compared with the other alternative routes. Between 30 and :0 private dwellings would have been affected, plus two Public Houses and about ten shops. Many of the private houses are of a high quality, some with preservation orders in force and the cost of acquiring all the necessary land and property would have been in the region of £300,000 at 1969 prices. (ii) Since the existing approach gradients to the village are 54% to the west and 74% to the east, the altera- tions to these gradients would have been impossible without causing further demolition of property along re-aligned side roads. (iii) A considerable number of at-grade junctions would have been perpetuated. Routes to the N.E. and S.W. (Routes 'A' the adopted route and 'C') were both lines which were designed to clear the envelope of existing development, but which remained as close as possible to the existing line. As the routes traversed similar strata there was no geological advantage in either route. The gradients and curvatures for both routes were similar. The route chosen however, allowed a better horizontal alignment approach to all the proposed routes of Canterbury Bypass than Route 'C' and there would have been a redundant length of carriageway if Route 'C' were adopted. . From planning considerations, the adopted route was preferred and was in fact the route shown on the County Development Plan. Route 'C* would have caused the more serious and far reaching damage to amenity and farming, including Renville Farm, Great Pett Farm and Bourne Park, the latter being a fine example of 18th Century landscape together with Bourne House, a Grade I listed building. The Kent River Authority had no preference for either scheme and were only concerned that the bridge crossing the Nailbourne Valley had sufficient flood relief capacity. The Ministry of Agriculture, Fisheries and Food preferred the northern route and requested that it be kept as close as possible to the village, so as to minimise the amount of orchard land taken at the Canterbury end and because through Bifron's Park the land to the south-west was poorer and the top loam soil thinner. “/j adsat:L aAvas oo 05000 4a z \ ENA ACRUELE aK, me a Page 4. SS9VLS LYOdSY AYVNIWITSYd LY SALNOY JALLWNYA LIV L WYYovId SSS SS SSS Om ESS \A290 A28 < BLEAN N q Lj DUNKIRK SS i ss, C To Sandwich HARBLEDOWNS BYPASS] SS —™ Under Construction CHARTHAM eo *s D ca CANTERBURY BYPASS ~ N BRIDGE BYPASS Proposed sO. *\ | Under Construction BRIDGE “*ea>\\ B 2068 . A DIAGRAM 2 ) A252 To Charing RELATIONSHIP BETWEEN BRIDGE BYPASS AND THE EXISTING AND PROPOSED A2 NETWORK A2 2nd CARRIAGEWAY To Dover Bishopsbourne Road to a. Black Robin Lane &. SCALE: 1 INCH TO 1 MILE a A28 BARHAM DUAL CARRIAGEWAY = To Ashford Completed \\ Page 6 De Relationship of Bridge Bypass to Existing and Proposed Networks Bridge Bypass is one of a series of bypasses between Faversham and Dover, which were designed to take long-distance and local inter-urban traffic. out of the villages. All traffic approaching Bridge from Canterbury is diverted on to the Bypass and traffic requiring’ to stop at Bridge departs via a slip road. Similarly, at the Dover end of the scheme, the A.2 traffic is channelled along the Bypass and local traffic uses a slip road to reach the village. The proposed Canterbury Bypass will link with Bridge Bypass at Renville Farm and the old A.2 road can be restored to become a local route from Canterbury to Bridge. the Barham end of Bridge Bypass connects with existing dual carriagewaye The map on the preceeding page shows the route continuity between Boughton and Dunkirk Bypass, Harbledown Bypass, Canterbury Bypass and Bridge Bypass. bs Landscape Works The County Planning Officer suggested at Preliminary Report Stage that due consideration be given to landscaping the route through the Nailbourne Valley. Following a Public Exhibition held in Bridge Village Hall in November 1972, a large number of local residents expressed the opinion that the embankment crossing the Nailbourne Valley would be unsightly and it was decided to lower the embankment so that the completed embankment line became compatible with the end of Conyngham Lane. As a result, the earthworks balance could no lenger be achieved and the surplus chalk and head material were re-deployed on extensive landscaping works to disguise the main embankment. Land was acquired under licences in order to carry out these landscaping works and in full consultation with the Department of the Environment's Landscape Architect the mecessary plans were evolved. The accompanying drawings describe these proposals. 7 Accident Record of Old A.2 In the three years from October 1969 to September 1972, there were 26 personal injury accidents along the section of old A.2 between Bonny Bush Hill (B.2065) and the Canterbury end of the Bypass in which 43 people were injured, one fatally. fay ewe ew ww eee ane ™— ( WDei1S |DUOSDeSs D) SNYNOSTIVN SHL agvod ANYNOEsS3sy39d “Wty JOUOJIDPD Pe}DIIPUI SDaID paudjdDH SYNOLNOD TVNIDIYO MOHS SSNI1 NANO SYNOLNOID QSHSINIS MOHS S3SNIG 71N4 PX ae O9SOL:1 2)D9S = ( $21}2W Ul 1D UMOYS saBDUIDYD pdDoOY ) € WVYOVIC OSNIYNOLNOO-3Y AdVOSQNV1 = zm ame THe FET SE SBF Se SF SE FE SE SE SE Fw = > Pace 8 LANDSCAPE CROSS SECTION DIAGRAMS 4&4 - 7 ———— ee A GN The following cross sections indicate the additional fill on the Bridge Village side of the Bypass. The cross sections indicating the landscape fill on the Patrixbourne side are similar. 2° Each section shown commences at the centre line of the road. Sections 1980 and 2000 indicates the method of falsifying the cut-fill line, whilst sections 2380 and 2420 indicate the method of disguising the embankment. Note that a nominal 1.0 - 1.5 metres of embankment is still evident above the landscape fill and that the landscape fill rounds off into the embankment slope and gently merges into original ground level. DIAGRAM 4 CUT- FILL LINE (before landscaping) i Additional fiil _ Original Ground 34M. A.0.D. — . Proposed Increase 40 34 3:0 24 1:6 1:2 08 O4 O02 0 ——— —+—_—_—-+} — t $+—. 1 Existing : 37-76 37-74 37-80 37-94 3799 3609 3823 3630 38% [ Distance to Z 15.20 25 230 35 «40 #45 50 55 60 CHAINAGE 1980-00M DIAGRAM 5 Structural Embankment False Cutting Additional fill ; Ve | Original Ground a i i ee aa 32 M A.O.D. Proposed Increase Existing Distance to _£ 50 46 40 32 22 16 10 O7 O4 35-46 3557 35-67 35:79 3587 35-99 36-04 35-97 3613 36:28 20.25 30 35 #40 45 50 55 60 65 12 CHAINAGE 2000:00M DIAGRAM 6 STRUCTURAL EMBANKMENT — Embankment | — False Embankment height varies Wie Additional fill (re-contouring) R Original Ground : MULT Pre Proposed Increase 0 12 34 54 60 58 54 50 44 40 $2 24 1.8 1:2 08 O-4 02 0 Existing 2647 26-45 26-65 bb 2-51 26-60 24-67 2673268 . Distance to ¢, 15.20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 CHAINAGE 2380-:00M DIAGRAM 7 STRUTURAL EMBANKMENT Structural Embankment eee False Embankment height varies Additional fill (re contouring) 20M AOD Proposed Increase 76 7-2 70 6°8 64 60 54 46 40 23°87 3-95 23-93 -2390 2392 23-97 35 40 «45 16 38 5.6 Existing 70 75 80 85 90 95 100 105 110 115 120 125 25 30 Distance to¢ CHAINAGE 2420-00™M "6 2604 Page 10 SECTION Ii GENERAL DESCRIPTION AND SITE 1. Dimensions (a) (b) (c) 9.80 m at chainage 1520, whilst that at Pridge Down it is 11.76 m at The total length of this scheme was 5.6 km which included 2.0 km of dualling to the previous A.2 single carriageway, between Bonny Bush Hill (B.2065) and Black Robin Lane at Barham. There were additional works to Bekesbourne Read and Coldharbour Lane, together with junction works at Renville Farm, Bridge Hill, Bonny Bush Hill and Poorstart Lane. Re-routed farm access roads comprised Hlode Farm Access, Bifron's Park Access, Highland Court Hospital Access, Highland Court Farm Access and Ileden Farm Road. The scheme included five bridges which were:- (i) Bekesbourne Road Overbridge. (ii) Bifron's Park Subway - provides access between fields for agricultural vehicles and has two footpaths and one bridlepath diverted through it. {iii} Patrixbourne Road Underbridge - carries : the bypass over both Patrixbourne Road and the Nailbourne stream. (iv) Wighland Court Accommodation Bridge - carries a private access road over the bypass. (v) Coldharbour Lane Underbridge The principal dimensions of these bridges are given on the table opposite. The Bypass has dual 7.3 m carriageways, with 0.3 m edge-strips and a 0.3 m drainage channel on the low side. The dualling to the existing carriageway which traverses flatter ground has a 1.0 metre hardened strip on the low side and no drainage channel. There is a central reserve 4.5 m wide between road markings, of which the central 3.9 m is grassed and dished off-centre. The verge width is 3.5 m measured from the road edge markings, is dished in cutting and falis away from the road on embankment. The maximum depth of the cut at Bekesbourne Road is chainage 3320. ‘The maximum height above original ground level of the structural embankment in the valley is 10.01 m at chainage 2420 and is 700 metres in length. - Ti AlOudpueacdcn TT Z/GSL PUD 1/69, Sx f= 7 BITE ee TY ET) Rata on Pen iid bee Racer: —~ ei eee —_— { 6S1 MST TRY Utes e doa | 7St LSL o 2V Scldl I LuVd NOT ASS ONS 7L WVYOVIC |. NOILISS ONO] 1V91907039 Page 24. 0082 Gt Wvy¥9oVId ee jer = ke ho Ne “2 = RO ae) = o on x © iS = 8 a 8 2 8 3 S és = , | wibuo saddy athe t | —— | Du Patesip.ues | ~~ _ ee, i Luyvd NOILISS ONO} TVOI901 lO39 LaJ i: Page 2s: os S & a is e rs a rs) 3B wn = 2 2 = 3 S 3 : 3 3 2 3OVNIVHO 7 { yl i a a7 MDG _swddn| 4“ | re aoa | a Ay cy e a | Dy ge un pazDpanzoK9 | odd ' oa qu OID INO (NZ p8398[01g)Siv [| >> — = OLE ELV CIESE PUD L/ESE III Luvd 9! WVHOVIC NOILISS ONOT 1V91901039 Page 26 3e The Geole-w :- The solid fors:tion uncerlvin- the entire route is Upper Chalk. Tne formation is overlain by varying thick- messes of the suverricial deposits rrevriously listed. *Recent Alluviws’ is confined to the flood plain of the Xailbournc, 2 strean which sredocinanily flows throuch the *Walley Gravel" and only shuws itself alonz the river bed when the water level is sufficiently high. The Head Drick- earth is confined to to cistinct areszs, one at the northern end as a capping to the isn cround and ten, as a denrosit in the waller. The Head Material, sense strictu, unmerlies the Head BGrickeczrth at the northern end amd is fovnd aszin on the hich srocnd at Bridse corn. Ancther type of head, nanely the soliflucted chalk, lies om the vallev floor beneath the erarel. Smail izresaler denosits of illwash overlie the area known as ‘Side 'hil'*, which is the north fecing slope of the valley. The upper chalk can be cescrited «as medium hard to hard white fissured chalk containing occasional bards of flints. Archzectozical Remains Numerous Saxon craves were investizated by the Canterbury Archaeolosical Scciety, together wath various ot&er phenomena of interest historically. The fandingss were in the rain, concentrated at the Sarhan end of the scheme. SECTION Vv CONSTRUCTION DETAILS The scheme costs are summarised helow between Bishopsbourne Road and Black Robin Lane. Page 27 and are divided into Bypass costs and those for the dualling of the A.2 The estimates are based upon the tender received from Mears Construction Limited on ‘ith June, 1974. 1. ROADWORKS General, items, Site Clearance, etc. Accommodation Works and Fencing Drainage Earthworks Carriageway Construction and Surfacing Signs, Crash Barriers Pedestrian Subways/ Cattle Creep 2. BRIDGEWORKS 32 CONTRACT TOTALS BR _to BRL &£ 25,728 Sy 750 46,091 6,898 441,415 12,1245 238,035 Bridge re ow 203,576 98,840 225,40 5173943 9594952 13,377 67.75 1,686,873 624,719 2,341,592 Die eee 1055 has been added to each item to include for contingencics.e Total —_— a 229,304 104,598 271,531 524,641 701,357 25,522 67,745 1,924,908 . 624,719 2,549,627 The tonder received was for a variable price contract related to the Baxter Formulae, in line with the recommendations of the Economic Development Committee for Civil “nrineering (May 1971). Page 28 Earthworks : The major earthworks quantities are as follows:- Total excavation of suitable material 2. sss ese eee 478,000 m " " " unsuitable " 448 «om wee exe FOG,000 mr Total Fill required for structural embankment ... ... 305,000 m° 3 " " " a landscaping eon ere cre ece 279,000 m Landscape requirements were to some degree relatively flexible and an earthworks balance was achieved. No fill material was imported, and free draining material for use under the embankments was obtained from the valley gravel. The landscape area was stripped firstly to a depth of 150 mm (called the top soil strip) and secondly, to a further depth of 350 mm (called the sub-soil strip), where possible. The material thus accrued was stored for replacement over the landscape fill. The cut ‘slopes at Bekesbourne Road give a rounded appearance. The strata order is Head, Cryoturbated Chalk, and Upper Chalk for which cut slopes of 1 upon 24, 1 upon 14 and 1 upon 1 were used. The cut slopes at Bridge Down were based upon two layers of material, Cryoturbated Upper Chalk and Firm Upper Chalk, for which cut slopes of 1 upon 14 and 14 upon 1 were used. A 3 metre wide berm separates these two cut slopes and acts as an arresting platform for possible falling scree. For the excavation of chalk the standard Department of the Environment specification was modified by Kent County Council's method specification. This proved highly successful beacuse chalk earthworks progressed in adverse wet conditions. Briefly the specification requires the use of face shovels and trucks for the excavation and transportation of chalk, so that the chalk structure is disturbed as little as possible. The rocky chalk fill layer is placed 500 mm thick and compacted by three passes of a dead weight roller (2.6 - 5.2 kN/100 mm width of roll). (Finer chalk is placed as per standard specification). From previous experience it has been found that scraper and vibratory compaction equipment can apply too much work to the chalk structure, resulting in break down of chalk structure and increased putification Sections of these cuttings have been given in Diagrams 7 and 8. Drainage : The dished central reservation is drained by a french drain, as are the dished verges in cutting. On the main embankment, run off from the verges is allowed to pass over the embankment and is collected at the toe either in a french drain or a ditch, as appropriate. Run off from the metalled carriageway is collected in a positive drainage: system, consisting of a continuous dished channel with gullies. On the high ground where the carriageway gradients are Slacker, there is no positive drainage and 1 metre hardened strip is constructed on the low side. Page 29 As mentioned before, use was made of the ICL 1900 drainage program and the system is designed against a one year storm. The cost of constructing soakaways of differing sizes was compared with the mounting cost of consecutively larger diameter drainage pipes, discharging into each soakaway, in order to optimise the spacing of soakaways. Thirteen soakaways were meeded, each approximately 8 metres deep. In addition, the central area of the Bypass discharges into the Nailbourne. At the request of the Kent River Authority, oil-traps were built at all soakaways and the Nailbourne, to avoid pollution of the water-bearing strata. The drainage was designed for uPVC pipes and again for concrete pipes. These two alternatives were billed separately and the choice of construction was offered to the tenderers. The uPVC design was marginally cheaper and therefore adopted for the construction of the drainage systems. Carriageway Construction : Flexible, rigid and composite pavements were designed so that a total of six different pavement designs were optional in the bill. These are summarised on the diagram overleaf. The construction utilising a lean mix base was adopted as it was the cheapest solution. Flexible or composite pavement designs only were considered for side road construction. Machine laid concrete pavement was not considered on groundsof economy and discontinuity of construction. The existing side roads are flexible and are thus compatible with this decision. Again lean mix base carriageways were chosen for economy. For the concrete/flexible/composite alternatives, the areaof carriageway was 47,000 m°. Unavoidable main road flexible/composite construction amounted to 34,000 mj. Side Road flexible/composite construction amounted to 13,000 m°. Construction Programme :; The key areas for early activity were near Bekesbourne Bridge and Highland Court Bridge, for which diversions were needed. The ensuing earthworks then released bridgeworks activity and a further diversion over the Doverbound carriageway at the Canterbury end of the scheme allowed early advancement of remaining earthworks at ‘Bekesbourne Bridge. The Construction of Patrixbourne Bridge became closely associated in programme with the Highland Court Bridge due to the fact that the final earthworks activity,dependant on finishing Highland Court Bridge was used to complete the earthworks around Patrixbourne Bridge. There were very few minor alterations to design detail during construction and drainage, formation, sub-base, lean mix and surfacing -activities followed each other with very little delay. STANDARD DETAIL FOR 7-9 METRE CONSTRUCTION IN FLEXIBLE OR COMPOSITE MATERIALS {8.6 Metre construction is similar except one 300 mm marginal strip is widened to 1000 m)as shown for concrete construction) ‘Oe 2BDY 4500 Central reserve 3500 Standard verge 7300 Carriageway 300 Marginal strip DIAGRAM 17. 300 Marginal strip Slope varies 150mm topsoil Wearing course Base course Road base > Combined filter pipe french drain and carrier pipe French drainand filter pipe. Sub base IN CUTTING DIAGRAM. 18. 3500 Standard Acceleration 7300 Carriageway 4500 Central reserve normall Deceleration lane , widening varies Marginal strip Marginal strip Marginal strip | (300 300 : sn (IIS 1 sone) N\ sto Slope varies Baw we Wearing course DETAIL B| | . Base course 150mm t | Ay isla mae Road-base . o Sub-base = Combined filter pipe french ON EMBANKMENT rain caries pine — gu a me es ee oe oo ee eee | STANDARD DETAIL FOR:7 9 METRE CONSTRUCTION IN FLEXIBLE OR COMPOSITE MATERIALS (86 Metre constructionis similar except one 300mm marginal strip is widened to 1000 m)as shown for concrete construction DIAGRAM 19 Filling of suitabte excavated material DIAGRAM 20 Wearing: course Base course Road-base - Sub-base No chippings in marginal strips except at channel [Carriageway fall Topsoi| Wearing course Base course DETAIL A Varies Carriageway fall |] Sub base continued __to filter drain , int 400 X 150 Precast concrete eas oer ot channel block bedded on 10mm cement mortar. DETAIL B 300 DIAGRAM 21 Fall 300 TYPICAL DITCH DETAIL 600 Combined filter pip french drain and carrier pipe. ‘Le 26pyg FLEXIBLE AND COMPOSITE PAVING ALTERNATIVE DESIGNS DIAGRAM 22 ee EE (Note for this scheme the Lean Concrete Road Base Design was adopted ) CONSTRYCTION THICKNESS TYPES OF ROADBASE FLEXIBLE PAVEMENT oes Fn } «6CCMPGSITE PAVEMENT | Tabie 85. GreuaP ) M3 VACADAM WEARING COURSE {ynote 210, Group W) BASE COURSE [Tabte 21¢,Group W) ROADZASE . iAs ‘ndiceted) SU5-BASE [Chalk C5" 339] [Teb'e T5.Grevp Ll) (Stande-d thickness] ADDITIONAL SUB 8452 [Head} [Teble TS Group Subcrade CBR2:2% ALTERNATIVE TO SODITIONAL SUB-BASE TOTAL CONSTRUCTION TRICXNESS CN CHALK TOTAL CONSTRUCTION THICKNESS QN HEAD OR WITR ALTERNAT VE ie METRE IF CHALK OVERLAY IS USEO. NOTE. Rolled Asshalt Weorng Course shatl be as described in Table 21A ane Clause 907S ond in addition shal! conform to “arte 7,Schodue + using rock types 1 to 7, or Taple$ Schedule 9 of B.S.594 (1962). ; ‘Ze @Bp nm mm ee eee Ee Se SS Se SS SSS SS CONCRETE PAVING ATTERNATIVE DESIGN ( Not ado ted } DIAGRAM 23. CONCRETE SLAB CONSTRUCTION LONGITUDINAL JOINTS Att concrete slablreinforced or unreinforced) UNREINFORCED SLABS TRANSVERSE JOINT SPACING Expansion joints at 60m max.(72m if limestone aggregate is used throughout.) Intermediate contraction joints at 5m.{6m if limestone aggregate is used throughout.) Warping joints may replace not more than 3 contraction Joints in succession except where dowel bar placers used. REINFORCED SLAB REINFORCEMENT -Mesh: min 3.9 kg/m’. Bar :min 450 mm/m. Cover :60mm from top of slab. TRANSVERSE JOINTS Every 3%joint to be an expansion joint remainder to be contraction joints. RELATION OF REINFOREMENT WEIGHT AND JOINT SPACING Spacing of joints (m) 3 4 5 6 Weight of reinforcément { kg/m?) [ Extract from Road Note 29. 3%Edition figure 13] DIAGRAM 24. CONSTRUCTION THICKNESS 80 CONCRETE SLAB REINFORCED OR UNREINFORCED SUB BASE (Table 7S Group N) 0 STANDARD THICKNESS ADDITIONAL SUB BASE CHALK (Table 7S Group N) 230 130 (Frost susceptible subgrade) TOTAL CONSTRUCTION THICKNESS (Frost susceptible subgrade) 450 DIAGRAM 25. - WARPING JOINTS Sealant depth: hot poured 15 20mm cold poured12 15mm L 12mm dowels at 270mm cé& for 220mmslab. 240mm c% for 240 mm slab. "€€ eBDY a Q STANDARD DETAIL FOR 8-6 METRE CONCRETE CONSTRUCTION (not adopted) rs (7,9 metre construction is similar as shown for flexible / composite construction, Diagrams 17. & 18) ta DIAGRAM 26. ‘ Standard verge 4200 7300 Carriagewa Central reserve | 1009 wrt strip 300 Marginal strip 300 oS 150mm topsoil, 1in40 slope Slope | 1in 20 ts a Sr = : i as ————— 2 aT — | | [so io 150 mm topsoil . , Su b-base the t Concrete sla 150 mm topsoil Lo French drain P and filter pipe Water proof membrane underlay Combined filterpipe french drain and carrier pipe DIAGRAM 27. IN CUTTING DOVER BOUND CARRIAGEWAY | Standard verge 4200 7300 Carriageway Central reserve varies 1000 | Marginal strip 300 Marginal strip | ins Slope ! 300 a Concrete slab 7 0 Ha = oo membrane underlay — 300 a 150 mm topsail ft = 150mm topscil Formation drain Type A Filter pipe and 4 back fill (Clause 505) french drain. 300 75 mmperforated pipe. ON EMBANKMENT DOVER BOUND CARRIAGEWAY mee we SF SS DD DS SS fe SS SS Ee SS BS fe fS a SECTION Page35 Vi PUBLIC UTILITIES AND BODIES' Enquiries were sent out to the following public bodies and services for their observations and no objections were received:- (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) The The The The The The The South Eastern Gas Board South Eastern Electricity Board Thanet Water Board ) Now Combined as ) Southern Water Authority Kent River Authority ) , Post Office Telephones | Central Electricity Generating Board Ministry of Agriculture, Pisheries & Food Bridge Blean District Council (now Canterbury District Council) Kent County Constabulary Kent County Council, Planning ‘Department The cost of modifying the Statutory Undertakers plant was £90,000 approximately, made up of £68,000 for the Bypass section and £22,000 for the dualling scheme. No extraordinary or difficult works were undertaken under this heading. Page 36 SECTION Vil BRIDGES Bekesbourne Road Overbridge is a single span bridge with a cast in situ post=-tensioned concrete deck of constant cross- section. The reinforced concrete abutments and wing walls are on spread foundations. The deck is simply supported and free to move longitudinally one end, but is restrained transversely by side restraint bearings, whereas at the other end it is restrained from movement both longitudinally and transversely by mortice and tenon joints between the underside of the deck and the top of the abutment beam seat. The deck is free to rotate at both abutments, The concrete face on the abutments is. "as struck" without featuring - whereas wing walls have a feature formed by implanting rectangular shapes of 20 mm plywood on the formwork. Lach abutment is inclined towards the deck both to improve the visibility around the Bypass curve and to achieve a better structural balance between the abutments and wing walls. The other solutions considered were firstly, a four span bridge with a reinforced concrete’ simply supported deck on leaf columns and end bank seats with spread foundations to the sub-structure and secondly, a three span “continuous post-tensioned deck on similar sub-structure. Both solutions reduce the visibility on the Bypass and the latter has a more complicated deck articulation leading toa more costly design. Bifron's Park Subway is a single span bridge with a cast in situ reinforced’ concrete deck on mass concrete abutments. The abutments and wing walls are on piled foundations. The abutments are designed as propped cantilevers with the deck providing the prop reaction, thus backfilling of the abutments cannot take place until the deck has been cast and the concrete has attained the required strength. The foundations are niled because of the low bearing capacity of the sub-soil. Reinforced concrete cast in situ ground beams are used as struts between the abutment foundations to prevent a rotational failure of the abutments. Vertical groove featuring is employed on the faces of the abutments and wing walls. The headroom clearance of 3.2 m was agreed with both the landowner and the tenant farmer for whom the subway is being provided. The other solutions considered were firstly, an Armco subway and secondly, a simply supported reinforced concrete deck on combined reinforced concrete abutments and base slab. The first was eliminated because of the small construction depth available and the second considered to be marginally more costly. ‘ Page 37. SS INSWLNEVY 1SV3 NO NOILWAS13 00% | NOILVASTS NOILO3S | ‘8 WVYOVIG AVIAGNS AdVd S,NOYNSIG . Page 38. ]@Ad) B64aA Jo yg Lisgligh yaddivg | Day _——\ LNAWLNGV LSV3 40 NOILVASI3 SS ; J ogsz [e) ‘ , SZO0Z| ADMabDiss0D | Gggy oO} CFIy S81 JD/ 009 SalIDA NOILVAS13 IVNOILDSS 0062 Cog) 0062 -*6C WVYSVIG A9GIue QVOY SNYNOgS3Sysa Page Patrixbourne Road Underbridge is a three span bridge in which each deck span is simply supported and consists of precast, .pretensioned concrete 'M' beams and in situ slab. The deck Spans are supported on piled reinforced conerete lintels and columns and on piled cantilever abutments. The deck is restrained from movement both longitudinally and transversely at the column lintels and at the north abutment by dowel bars through the bearings. At the south abutment PTFE sliding bearings allow longitudinal movement but transverse moveinent is prevented by side restraint bearings. Rotation is allowed at all joints. The intermediate supports including the lintel beams are designed to resist all forces resulting from restraint to thermal movement and flexure of the columns. Piled foundations are used to avoid the high settlements which would result with spread foundations. The concrete finish to the abutment walls and columns is "as struck" and vertical groove featuring is used on the wing walls. The alternative solution of an in situ reinforced concrete deck with all spans simply supported on similar sub-structure was considered to be more costly and the chosen solution was selected both on the basis of economy and case of construction over a river. Hichland Court Accommodation Bridge is a three span bridge with a continuous cast in situ post-tensioned deck on reinforced concrete abutments and picrs with spread foundations. © The deck is restrained from movement both longitudinally and transversely at one end by a reinforced concrete mortice and tenon joint between the underside of the deck and the abutment beam seat. At the other end a side restraint bearing allows longitudinal movement only. Sliding bearings on the colunns allow both longitudinal and transverse movement. The deck is free to rotate at all supports. The columns are free standing, encastre with their foundations. A plain "as struck" finish is used for all conerete faces. Fer accommodation reasons the height of the parapet railing is increased to 1.8 m by modifying the standard P2 posts and the parapet posts and connections are designed to resist the higher wind forces generated by the additional wind resistance. The other solutions considered were firstly, a single 40 m span, post-tensioned deck of varying section and secondly a four span continuous deck in reinforced concrete. The'first was found to be too costly, the second was considered to be about the same cost as the chosen solution, but was rejected in favour of the three span solution which was felt to be safer. Coldharbour Lane Underbridge is a single span bridge with a reinforced concrete deck of constant cross-section on reinforced concrete abutments. The abutments and wing walls are on spread foundations. At one end the simply supported deck is free to move longitudinally, but prevented from transverse movement by side restraint bearings. At the other end the deck is restrained from movement both longitudinally and transversely by mortice and tenon joints between the underside of the deck and the top of the beam seat. Rotation is permitted at both ends. ° The abutment face has a plain concrete "as struck" finish whereas the wing walls have a feature formed by implanting a pattern of rectangular shapes of 20 mm plywood on the formwork. The alternative solution considered was a three span bridge with a simply supported reinforced conerete deck on leaf columns with: end bank seats, but this was considered to be more costly. Page 40. NOILISS SSOuYD l jaddsdg |DJaW OO0LsSz TT nn en NOILVAS13 IVNOILOSS Q, . \ \ \ —_ , eer | OSz6L ‘O€ WVHOVIC 3901 GVO SNYNOEXiulvd | = = ee i i i i i | i Go COLDHARBOUR LANE BRIDGE , DIAGRAM 31. _ 13200 13130 13200 Se . — a AAAI | GE pS \‘K AX AN WE Soe UNI 2560) 7311 2560 SECTIONAL ELEVATION ~ —— NETTIE LEU f LETTE TV) im |_| | |_| |_| |_| |_| |_| a a a |_| ELEVATION OF WEST ABUTMENT woke oo Vy abby HIGHLAND COURT ACCOMODATION BRIDGE DIAGRAM 32. 7900 900} 7900 | SECTIONAL ELEVATION 3500 1} —-— Pedestrian. vehicular barrier modified for extra height. Void Formers 9200 TYPICAL CROSS SECTION z4 26vnq Materials Used Driven, cast in situ piling In situ concrete Steel reinforcement Prestressing steel (stressed in situ) Precast concrete pretensioned beams _ Rubber bearing pads Vehicle parapet railing (aluminium) 2563 5320 600 28 72 84 531 Page 3 lin.m. cu.eme tonne tonne No. No. lin.em. Page ah SECTION VIdIt HIGHWAY SERVICES No special highway services are incorporated into the scheme. The majority of signs are reflective, the remainder, in particular locations being lit. APPENDICES Main Contractor a) b) c) d) e) f) ‘Mears Construction Ltd., Sydenham, London Contract start date : 27th August, 1974. Contract completion date : 26th August, 1976. Length 3.8 km of dual carriageway 1.8 km of single carriageway (dualling alongside existing A.2) Variable Price tender SUM secececceee £2, 325,028 (concrete alternative escccccccecccece £2,478,068) Tender Date : 4th June, 1974. Principal Sub-Contractors a) b) c) d) e) Blackwell's (Rkarthmovers), Earls Colne, Essex Frankipile Ltd. Anglian Building Products Ltd. P.S.C. Equipment Ltd. E.J.Ellis & Co. Ltd. (Paving) It Progress Photographs These were taken at six weekly intervals at key positions throughout the site. Sbeta ey Ss Wee AS x . <2 ¥ ++ we b~ -2 - . ee est Qi or ; oa Neg, eer ceca —~ Sai Sette | Bifro ! n 's ‘s ubway Con . EN DS Rabe eae Vs alge aa os ar tier tae ae wie Lee oe Mey, hepa orion Bypass route looking towards Canterbury Bypass Route looking towards Canterbury fy tay, aie e eee aS Sad 3 oe O54 Chainage 2600/2700 26/Sept/197"4 Piling Rigs and Batching Plant at Patrixbourne - looking towards : Canterbury ee suliey Ls Ao i “f : . Siete Sy, cen ae jeore Maret 1 ee = ite oe. _y a ; a if UH ety it i eh: B ‘ill eererer Titi: iAH i ill 27 ¥2 b mart Wd tte ' eva 47 eM atric i eee , t ty! ow 24/April/75 Patrixbourne Bridge Construction AMD re Ge > med ET tee id Wn PH, i cea ty at hag BO: el uoT}ONAZSUOD 8dpT14g G2Z/eunc/S auUIMogxXt43eg Chainage 2990 Bypass Route looking towards Canterbury 16. oct. 1IG7H Chainage 2400 Bypass Route looking towards Canterbury D | AY . 26/Sept/1974 Side Hill Wood Shows access road to Highland Court RM AJENUDL EU Chainage 3400 Bypass Route looking towards Canterbury i ipe teeta? : wos Le nee wee oe ee ee a ee GZ6l ‘aaqueydas eSptag uotzepoumossy MoD pueTYys ty = ee i Pepe ne Fy net a Aad | —- sa are oF ree me & a.¥ ee : ~, 2 MNS EN ae = face ed — Plant Scenes ‘ G = = = ~- — “ og > 5 “ay ee rater es Coldharbour Bridge Construction = EE f= ul a = he GU ee Lie. ty) ee i wo | RAasS INiyy Bh bateeh 979 a | 1 3 aa | cy TH ACOA Ce said bet obey Fy 5/June/75 Coldharbour Bridge Construction Coldharbour Lane Construction 6/Feb/1975 Bypass route looking towards Canterbury Bypass Route looking towards Canterbury al =. ui = a | al t PHOTOGRAPHS ILLUSTRATING THE COMPLETED SCHEME * > eI UN lS 9LEL AP OT = yen — a Tas ¢ oping a f vay!) ets 5 tS pe ge ee . 2 as ey Rs ay SE = yt! nS pte pinta Oe eae Rae Oe ae ws Tee a ad a) ee 7 ci ¥ y Ligait’, be fps AE Ra &% GA et Ange 1 Ng wwe ¥ vs oy , Jy ( iy ’ po ed WO bis 2 { fa iA ge JaA0g sptesoz SuTHooT M4. 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