DMRB VOLUME 6 SECTION 1 PART 1 - Standards …

1 February 2002 DESIGN MANUAL FOR ROADS AND BRIDGESVOLUME 6 ROAD GEOMETRYSECTION 1 LINKSPART 1TD 9/93 - AMENDMENT NO 1 HIGHWAY LINK DESIGNSUMMARYThe Standards sets out the elements of design andprinciples for their co-ordination, for geometric designof an existing carriageway or new build situation. TheStandards include a revised Chapter 5 and deletesAnnexes B and FOR USEThis amendment is to be incorporated in the existing contents page for VOLUME 6, andinsert new contents page for VOLUME 6, datedFebruary existing cover sheet for Highway LinkDesign and insert new cover existing TD 9/93 contents sheet andinsert new TD 9/93 Amdt No 1 contents existing Detailed contents of Chapters1-8 sheet and insert new sheet dated existing Chapter 0 Foreword pages0/1, 0/2 and 0/3 and insert pages 0/1 and 0/2dated February existing Chapter 5 (including Annexes Band C)

2 , and insert new Chapter the Amendment Sheet at the front of thedocument after the new cover details of Amendment No 1 on Registrationof Amendment sheet and sign and date toconfirm the amendment has been sheets 9/1 and 10/1 and insert newsheets dated February this sheet as : A quarterly index with a full set of VolumeContents Pages is available separately from TheStationery Office 9/93 IncorporatingAmdt No 1 datedFebruary 2002 Highway Link DesignSummary:The Standards sets out the elements of design and principles for theirco-ordination, for geometric design of an existing carriageway or new buildsituation. The Standards include a revised Chapter 5 and deletes Annexes Band MANUAL FOR ROADS AND BRIDGESTHE HIGHWAYS AGENCYSCOTTISH EXECUTIVE DEVELOPMENT DEPARTMENTTHE NATIONAL ASSEMBLY FOR WALESCYNULLIAD CENEDLAETHOL CYMRUTHE DEPARTMENT FOR REGIONAL DEVELOPMENTNORTHERN IRELANDV olume 6 SECTION 1 part 1 TD 9/93 Amendment No 1 February 2002 REGISTRATION OF AMENDMENTSA mendPage NoSignature & Date ofAmendPage NoSignature & Date ofNoincorporation ofNoincorporation ofamendmentsamendmentsRegistration of AmendmentsVolume 6 SECTION 1 part 1 TD 9/93 Amendment No 1 February 2002 REGISTRATION OF AMENDMENTSA mendPage NoSignature & Date ofAmendPage NoSignature & Date ofNoincorporation ofNoincorporation ofamendmentsamendmentsRegistration of AmendmentsVOLUME 6 ROAD GEOMETRYSECTION 1 LINKSPART 1TD 9/93.

3 AMENDMENT NO 1 HIGHWAY LINK to Coordinated Link 2 Lane Carriageway Carriageways and AHarmonic Mean VisibilityDESIGN MANUAL FOR ROADS AND BRIDGESF ebruary 2002 Detailed Contents of Chapters 1 to 8 ELEMENTS OF SpeedGeneral1/1 Factors Affecting Speed1/1 Selection of Design Speed1/2 Design Speed Related Parameters1/3 Changeover of Design Speed Standards1/4 Connection to Existing Roads1/4 Selection of Parameter Values1/4 Relaxations1/4 Departures1 DistanceStopping Sight Distance2/1 Full Overtaking Sight Distance2/1 Obstructions to Sight Distance2/1 Relaxations2 AlignmentRoad Camber3/1 Superelevation3/1 Desirable Minimum Radius3/2 Relaxations3/2 Appearance and Drainage3/2 Application of Superelevation3/2 Widening on Curves3/2 Lane Width Reductions at Pinch Points3/3 Transitions3/3 The Effect of Sight Distance at Horizontal Curves3 AlignmentGradients4/1 Vertical Curves4/1 Relaxations4 LanesIntroduction5/1 Scheme Appraisal5/1 Layout - Single Carriageways5/6 Layout - Dual Carriageways5/19 COORDINATED LINK to Coordinated Link DesignGeneral6/1 Rural Roads6/1 Urban Roads6 2 Lane Carriageway RoadsGeneral Principles7/1 Overtaking Sections7/1 Non-overtaking Sections7/5 Obstructions to Overtaking7/5 Non-overtaking Crests7/6 Overtaking Value7/7 Horizontal Curve Design7/9 Vertical Curve Design7/10 Junction Strategy7/10 Changes in Carriageway Width7/13 Road Markings7/14 Existing Single Carriageway Improvements7/14 Staged Construction7 Carriageways and MotorwaysGeneral Principles8/1 All Purpose Dual Carriageways8/1 Motorways8/2 DESIGN MANUAL FOR ROADS AND BRIDGESF ebruary

4 2002 VOLUME 6 SECTION 1 part 1 TD 9/93 Amendment No 1 February 20020/1 Chapter 0 Foreword0. Standard applies to both single and dualcarriageway roads in both urban and rural areas. It shallbe used to derive the Design Speed, and the appropriatevalues of geometric parameters for use in the design ofthe road alignment. It states the basic principles to beused for coordinating the various elements of the roaddesign, which together form the three dimensionaldesign of the Standard replaces completely the followingdocuments which are hereby withdrawn:TD 9/81 Highway Link DesignTD 9/81 Amendment No 1 dated January 1985TD 9/81 Amendment No 2 dated March 1991 Layout of Roads in Rural Areas (and metricsupplement)Roads in Urban Areas 1966 (and metric supplement)Motorway Design Memorandum (1962 et seq)TA 28/82 Layout of Roads in Rural AreasA guide to revisions 1982TA 32/82 Roads in Urban AreasRevisions subsequent to A guide to revisions 1979 TA 43/84 Highway Link DesignPrevious Chapter 5.

5 Climbing Lanes has been revisedand Annexes B and C of the Advice Note TA 43/84, HighwayLink Design, are superseded by the changes to thisStandard itemised in Paragraph of the Advice Note is hereby withdrawn pending a reviewof this of Chapter 6 and Table 4 were supersededby TD 20/85 Traffic Flows and Carriageway WidthAssessment ( dmrb ). The superseded text hasbeen removed from Chapter 6 and Table format has been changed to that required forthe Design Manual for Roads and Bridges ( dmrb ).The Paragraphs have therefore been as noted in Paragraphs and 07, the Standardis material has been added to this edition ofthe standard updating the approach to be taken whenconsidering the application of alignment parametervalues less than Desirable Minimum. The followingParagraphs have been amended or added to reflect thisand the changes identified in Paragraph to to to to inclusiveTable parameters are now based upon DesirableMinimum values, except for Sag Curves which have notpreviously had Desirable Minimum values.

6 Valuesbelow that are expressed in terms of numbers of DesignSpeed steps below Desirable Minimum. References toAbsolute Minimum for other than Sag Curves havebeen deleted. Where existing Standards refer toAbsolute Minimum values contained in this Standard,these shall be taken as one Design Speed step belowDesirable Minimum editorial changes have been introduced toassist in the application of the Standards , but withoutchanging the Standard should be used forthwith for thedesign of all schemes for the construction and/orimprovement of trunk roads currently being preparedprovided that in the opinion of the OverseeingDepartment, this would not result in any significantexpense or delay progress. Design Organisations shouldconfirm its application to particular schemes with theOverseeing A major objective of this Standard is to ensurethat designs achieve value for money without anysignificant effect on safety.

7 The design systems thatVolume 6 SECTION 1 part 1 TD 9/93 Amendment No 1 February 2002 Chapter 0 Foreword0/2have been developed in relation to both Design Speedand the related geometric parameters will result in amuch greater flexibility to achieve economic design indifficult circumstances. In addition, detailed attention isgiven to the design of single carriageway roads, wherethe previous recommendations have been considerablyextended to allow greater flexibility for design, withparticular emphasis upon the coordination of designelements to improve safety and overtaking , the greater flexibility for design introduced bythis Standard will enable more economic design,reducing both the construction costs and the impact ofnew roads and road improvements on the Throughout this Standard, there is a continualreference to the use of the cost/benefit programmeCOBA (Scotland - NESA)

8 , which shall be used at allstages to test the economic performance of alternativescheme The Standards contained in this documentrepresent the various criteria and maximum/minimumlevels of provision whose incorporation in the roaddesign would achieve a desirable level of performancein average conditions in terms of traffic safety,operation, economic and environmental effects. In mostcases, with care, designs can be achieved which do notutilise the lowest levels of design parameters given. Atsome locations on new roads or major improvements,however, it may not be possible to justify even thelowest levels of design parameters in economic orenvironmental terms, due to high costs, low trafficlevels, and environmental damage etc. In such cases,sufficient advantages might justify either a Relaxationwithin the Standards , or in more constrained locations aDeparture from the Standards .

9 The various parametersquoted in this Standard are not, therefore to be regardedas sacrosanct in all circumstances. Relaxations andDepartures should be assessed in terms of their effectson the economic worth of the scheme, the environment,and the safety of the road user. Further details on theuse of Relaxations are given in Chapters 1 to Designers should always have regard to the costeffectiveness of the design provision. In some cases,such as gradients, dmrb VOLUME provides amethod of quantifying the economic trade-offsassociated with Relaxations. In others, the implications,particularly in relation to safety may not be quantifiableand the Designer must apply the judgement ofexperience in proposing a Relaxation or When issued in 1981, this Standard introducedthe concept of a hierarchy of permitted values forgeometric layout parameters (visibility, horizontalcurvature & vertical curvature).

10 This hierarchy wasbased upon Desirable Minimum Standards , with lowervalues being known progressively as Relaxations andDepartures. Values equal to or higher than DesirableMinimum give consistently safe alignments andminimise journey times. Research had shown that inmany situations safety was no worse with values lowerthan the rigid requirements of the previous hierarchy of values enabled a flexible approach tobe applied where the strict application of DesirableMinimum requirements would lead todisproportionately high construction costs or severeenvironmental impact upon people, properties andlandscapes. Successive levels in the hierarchy invokedmore stringent consideration in line with the need tocarefully consider During the years since 1981 there have beenmany advances in road layout design.