VOLUME 7 PAVEMENT DESIGN AND MAINTENANCE SECTION 5 ...

February 1999

DESIGN MANUAL FOR ROADS AND BRIDGES

VOLUM E 7 PAVEMENT DESIGN ANDMAINTENANCE

SECTION 5 SURFACIN G ANDSURFACING M ATERIALS

PART 1

HD 36/99

SURFACING M ATERIALS FOR NEWAND MAINTENANCE CONSTRUCTION

SUMMA RY

This standard provides a summary of surfacing optionsavailable for use on both flexible and rigid pavementsand advises on current requirements for surfacing. Italso details requirements for aggregates previouslycovered in HD 28 (DMRB 7.3.1) and gives advice onsurface texture.

INSTRUCTIONS FOR USE

This is a new document to be inserted into the manual.

1. Insert HD 36/99 into Volume 7 Section 5 Part 1.

2. Archive this sheet as appropriate.

Note: A quarterly index with a full set of VolumeContents Pages is available separately from TheStationery Office Ltd.

HD 36/99

Surfacing Materials for New andMaintenance Construction

Summary: This standard provides a summary of surfacing options available for use onboth flexible and rigid pavements and advises on current requirements forsurfacing. It also details requirements for aggregates previously covered inHD 28 and gives advice on surface texture.

THE HIGH WAYS AGENCY

THE SCOTTISH OFFICE DEVELOPMENT DE PARTMENT

THE WELSH OFFICEY SWYDDFA GYMREIG

THE DEPARTMENT OF THE ENVIRONMENT FORNORTHERN IRELAND


Volume 7 Section 5Part 1 HD 36/99

February 1999

REGISTRATION OF AMENDMENTS

Amend Page No Signature & Date of Amend Page No Signature & Date ofNo incorporation of No incorporation of

amendments amendments

Registration of Amendments


February 1999

REGISTRATION OF AMENDMENTS

Amend Page No Signature & Date of Amend Page No Signature & Date ofNo incorporation of No incorporation of

amendments amendments

Registration of Amendments

VOLUM E 7 PAVEMENT DESIGN ANDMAINTENANCE

SECTION 5 SURFACIN G ANDSURFACING M ATERIALS

PART 1

HD 36/99

SURFACING M ATERIALS FOR NEWAND MAINTENANCE CONSTRUCTION

Contents

Chapter

1. Introduction

2. Surfacing Options

3. Texture and Aggregate Properties

4. Not currently used

5. Tyre/Road Surface Noise

6. References

7. Enquiries


February 1999


1. INTRODUCTION

Chapter 1Introduction

ea

e

onf

rr

n the

n

cts

ic

ct

1.1 This Part provides a summary of surfacingoptions available for use on both flexible and rigidpavements and advises on current requirements forsurfacings. The Part also details the requirements foaggregates to ensure that satisfactory skidding resisis provided on roads, this topic was previously coverin HD 28 (DMRB 7.3.1). This Part also includes detof surface texture and how this effects surface noise atthe tyre/road interface.

1.2 Brief descriptions of bituminous surfacingmaterials and surface treatments are given in HD 26(DMRB 7.2.3. and HD 31 (DMRB 7.4.1). Surfacetreatments for the maintenance of concrete roads argiven in HD 32 (DMRB 7.4.2).

1.3 Detailed information on bituminous materialtypes, and surfacing processes, together with adviceuse, is presented in HD 37 (DMRB 7.5.2). Details oconcrete surfacing and materials are given in HD 38(DMRB 7.5.3). Reference should be made to theSpecification (MCHW1) Series 700, 900 and 1000,together with the Notes for Guidance (MCHW2). Fosome materials there are British Standards and othepublished documentation and these are referenced iappropriate chapters.

Implementation

1.3 This Part shall be used forthwith on allschemes for the construction, improvement andmaintenance of trunk roads including motorways,currently being prepared provided that, in theopinion of the Overseeing Organisation this wouldnot result in significant additional expense or delay.Design organisations should confirm its applicatioto particular schemes with the OverseeingOrganisation.

Mutual Recognition

1.4 The construction and maintenance of highwaypavements will normally be carried out under contraincorporating the Overseeing Organisation'sSpecification for Highway Works (MCHW1). In such

February 1999

cases products conforming to equivalent standards a

rtancedils

specifications of other States of the European EconomArea and tests undertaken in the other States will beacceptable in accordance with the terms of the 104 and105 Series of Clauses of that Specification. Any contranot containing these Clauses must contain suitableclauses of mutual recognition having the same effectregarding which advice should be sought.

1/1

nd


Chapter 2Surfacing Options

2. Surfacing Options

2.1 The choice of surfacing materials/systems plays avital role in providing roads that meet the needs of theuser, that are safe and which give value for money. Formany years hot rolled asphalt with chippings rolled intothe surface has been the most widely used surfacing ontrunk roads, including motorways, for both newconstruction and major maintenance. Recent years havehowever, seen the development of new materials andtechniques, many of which are proprietary, that offersignificant advantages, not just to the road user but alsoto the environment. For example noise generation maybe reduced, delays at road works curtailed, ride qualityimproved and deformation resistance enhanced, all whilemaintaining existing safety levels. Furthermore newproducts such as energy efficient ‘cold-lay’ materials arein their development phase. This Chapter gives guidancon the range of surfacing options which are nowavailable for both new construction and maintenance.

Performance Specifications

2.2 To remove barriers to trade and to encourageinnovation, the Construction Products Directive (CPD)of the European Union requires the introduction ofperformance related specifications wherever possible.Specification clauses of this type have been included inthe Specification for Highway Works (MCHW1&2)covering surfacings such as surface dressings (Clause922), slurry and micro-surfacings (Clauses 918 & 927),high friction surfacing (Clause 924), porous asphalt(Clause 938), thin wearing course systems (Clause 942and hot rolled asphalt (Clause 943). Performance isassessed either by testing samples from the laid materiatesting the laid material in-situ or for proprietarysystems, by assessment and approval in advance undethe British Board of Agrément Highway AuthoritiesProduct Approval Scheme (BBA HAPAS). As BBAHAPAS becomes established it should be possible tosimplify specification requirements where covered by thecertification.

2.3 Where BBA HAPAS certification is specifiedbut certificates are not yet in place, or in EnglandHA Type Approval has not been given, theapproval of the Overseeing Organisation shall besought and a Departure agreed.

C

2inpO(Sa

•

•

•

•

•

2roathcss7swsju

2hae

•

•

•

2g

February 1999

e

)

l,

r

hoice of Surfacings

.4 Apart from the suitability of surfacing materials terms of safety and robustness, the permittedavement surfacing options have been determined by theverseeing Organisations, as indicated in Tables 2.2(E),), (NI) and (W), taking account of the variations

cross the UK of a number of factors:

the nature of the existing network

population density

traffic intensity

climatic conditions

availability of materials

.5 In locations where speeds are limited and tyre/ad generated noise is low, or where traffic intensity

nd therefore the overall noise level is not very great,en the full range of surfacings options should be

onsidered. For example, surface dressing systemshould always be the first option to be examined forimple restoration of skid resistance, see HD 37 (DMRB.5.2) and for major maintenance, the brushed concreteurfacing option should be included. The decision onhich options are to be included should be made on aite specific basis but none should be ruled out withoutstification.

.6 Where noise levels are high due to the intensity ofigh speed traffic, a range of surfacing options isvailable that can reduce tyre/road generated noisemission. These are:

hot paver-laid thin wearing course systems,Specification Clause 942 (MCHW 1),

exposed aggregate concrete surfacing, commonlyknown as ‘whisper concrete’, SpecificationClause 1044 (MCHW 1),

porous asphalt, Specification Clause 938(MCHW 1).

.7 Advice on the different types of surfacings isiven in HD 37 and 38 (DMRB 7.5.2 & 3), and a brief

summary description provided in Table 2.1.

2/1



2.8 The surfacing options permitted shall bethose shown in Tables 2.2E, 2.2S, 2.2NI and 2.2W,for England, Scotland, Northern Ireland and Walesrespectively. Where an option is permitted “for usewith restriction”, any restriction listed in therelevant HD shall apply and reference should bemade to the Overseeing Organisation.

2.9 In Table 2.2, high speed roads are defined as thosewith an 85th percentile traffic speed exceeding 90km/hr.The various construction types, eg. Flexible, FlexibleComposite, are defined in HD 23 (DMRB 7.1.1).

Material Summary Description

Brushed Concrete The traditional transverse brushed concrete surface.

Burlap Drag & The surface is finished using wet burlap (hessian) dragged behind the paving machine followed byTine Concrete transverse tining.Surface

Exposed Aggregate A quieter concrete surface with an exposed aggregate finish, commonly known as ‘whisper’ concrete.Concrete Surface(EACS)

Hot Rolled Asphalt A traditional surfacing material in the UK, formed by rolling pre-coated chippings into a stiff sand asphaltWearing Course (HRA) mat, to provide texture and skidding resistance.

Porous Asphalt (PA) A mix in which the aggregates form a skeletal structure with interconnecting voids in excess of 20%allowing water to drain away within its thickness. Usually used for its noise suppression properties in theUK, it also reduces spray in wet weather.

Thin Surfacings A range of materials, usually proprietary, that can restore skidding resistance and ride quality. Spray mayalso be reduced. Many have surfaces quieter than HRA. The range includes thin proprietary SMAs

Stone Mastic A mix in which the aggregates form a skeletal structure, with a high binder content. Unless very carefullyAsphalt (SMA) designed and controlled, mixes can be prone to loss of surface texture.

Bitumen Macadam A mix with a continuous aggregate grading, with moderate resistance to deformation and providing lowsurface texture.

Surface Dressing A system of one or more layers of sprayed binder and typically, single-sized chippings.

Slurry Surfacing and Bitumen emulsion binder and aggregate mixed just prior to laying. No systems have as yet demonstratedMicro-surfacing the ability to retain satisfactory surface texture under heavy traffic.

High Friction Surfacing Proprietary treatments using small sized high PSV aggregates for use in high-risk areas.

Table 2.1 Summary Description of Material Types

February 19992/2



This tab le is f or use

in England

onl y

✓✓✓✓✓ For use without restriction R For use with restriction x Not permitted

TABL E 2.2E (England): Permitted Pavement Surfacing Materials for New and Maintenance

Road Category High Speed Roads Low Speed Roads

HD No New Maintenance New MaintenanceConstruction Construction Construction Construction

FLEXIBLE

HRA HD37ch4 x R x R

Coated Macadam x x x x

Porous Asphalt HD37ch5 R R R R

Thin Surfacings HD37ch6 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓

SMA HD37ch7 x x x x

Surface Dressing HD37ch8 x R x R

Slurr y / Micro Surfacing HD37ch10 x x x R

FLEXIBLE COMPOSITE

HRA HD37ch4 x R x R


Porous Asphalt HD37ch5 x x x x


SMA HD37ch7 x x x x


Slurr y Seal / Micro Surfacing HD37ch10 x x x R

RIGID

Whisper Concrete HD38 Ch 3 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓

Brushed / Burlap Drag / Tined HD38 Ch 2 x R x R

HRA HD37ch4 x R x R

Porous Asphalt (CRCP only) HD37ch5 x R x R

Thin Surfacings HD37ch6 R ✓✓✓✓✓ R ✓✓✓✓✓

SMA HD37ch7 x x x x



RIGID COMPOSITE

HRA HD37ch4 x R x R



SMA HD37ch7 x x x x



February 1999 2/3

Construction




in Scotland

onl y



FLEXIBLE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓



Thin Surfacings (See Note 2) HD37ch6 R R R R

SMA HD37ch7 R R R R

Surface Dressing (See Note 1) HD37ch8 x R x R


FLEXIBLE COMPOSITE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓




SMA HD37ch7 R R R R



RIGID


Brushed / Burlap Drag / Tined HD38 Ch 2 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓

HRA (See Note 1) HD37ch4 x ✓✓✓✓✓ x ✓✓✓✓✓



SMA HD37ch7 x R x R



RIGID COMPOSITE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓



SMA HD37ch7 R R R R




Note 1: See Paragraphs 2.5 & 2.6 in relation to noise Note 2: See Paragraph 2.3 in relation to HAPAS

TABLE 2.2S (Scotland): Permitted Pavement Surfacing Materials for New and Maintenance Construction

February 19992/4




in Nor thern Ireland

onl y



FLEXIBLE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓

Coated Macadam x x ✓✓✓✓✓ ✓✓✓✓✓


Thin Surfacings (See Note 2) HD37ch6 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓

Generic SMA HD37ch7 x x R R

Surface Dressing (See Note 1) HD37ch8 x ✓✓✓✓✓ x ✓✓✓✓✓


FLEXIBLE COMPOSITE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓






RIGID


Brushed / Burlap Drag / Tined HD38 Ch 2 R R ✓✓✓✓✓ ✓✓✓✓✓

HRA (See Note 1) HD37ch4 x ✓✓✓✓✓ x ✓✓✓✓✓


Thin Surfacings (See Note 2) HD37ch6 x R x R

Generic SMA HD37ch7 x x x R



RIGID COMPOSITE

HRA (See Note 1) HD37ch4 ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓ ✓✓✓✓✓







Note 1: See Paragraphs 2.5 & 2.6 in relation to noise Note 2: See Paragraph 2.3 in relation to HAPAS

TABL E 2.2NI (Northern I reland): Permitted Pavement Surfacing Materials for New and MaintenanceConstruction

February 1999 2/5




in Wales

onl y


TABL E 2.2W (Wales): Permitted Pavement Surfacing Materials for New and MaintenanceConstruction



FLEXIBLE

HRA HD37ch4 R R R R




SMA HD37ch7 x x x x



FLEXIBLE COMPOSITE

HRA HD37ch4 R R R R




SMA HD37ch7 x x x x



RIGID


Brushed / Burlap Drag / Tined HD38 Ch 2 R R R R

HRA HD37ch4 x R x R


Thin Surfacings HD37ch6 R ✓✓✓✓✓ R ✓✓✓✓✓

SMA HD37ch7 x x x x



RIGID COMPOSITE

HRA HD37ch4 R R R R



SMA HD37ch7 x x x x



February 19992/6


3. TEXTURE AND AGGRREGATE PROPERTIES

Chapter 3Texture and Aggregate Properties

3.1 Friction between the tyre and road surfaceconsists of two main components, both of which arerelated to speed.

a) Sliding resistance between tyre and road surfacewith its magnitude determined by the nature of thematerials in contact.

b) Loss of energy caused by deformation (hysteresisof the tyre.

Therefore during a single braking operation the frictionavailable to the vehicle is not constant.

3.2 In dry conditions all clean, surfaced roads have ahigh skidding resistance. The fine scale microtexture(see Figure 3.1) of the surface aggregate is the maincontributor to sliding resistance and is the dominantfactor in determining wet skidding resistance at lowerspeeds. Coarse macrotexture which provides rapiddrainage routes between tyre and road surface, and tyrresilience as well as the fine scale microtexture areimportant factors in determining wet skidding resistanceat high speeds. Megatexture relates to the roughness ofthe road and has no effect on skidding resistance buteffects noise, (see Chapter 5 of this Part for details).

FIGURE 3.1 Surface Texture

3.3 The skidding resistance of wet roads is reduced bthe lubricating action of the film of water on the wetroad surface. Drainage channels provided by the largescale texture (macrotexture) and/or the pattern on thetyre, assist in getting rid of the bulk of the water and areof increasing importance the higher the speed.Penetration of the remaining water film can be achievedonly if there are sufficient fine scale sharp edges

(b‘

3ttaawtie

3beaaorsb

M

3sa

M

Macro

Micro

February 1999

)

e

y

microtexture) on the road surface on which the tyre canuild up high contact pressures to establish areas of

dry’ contact between the road and the tyre.

.4 Aquaplaning is the condition where the vehicleyres are completely supported by a layer of water andhere is no contact with the road surface. High speednd a thick film of water on the road surface encourage vehicle to aquaplane, but a relatively thin layer ofater could cause a problem if combined with low

exture depth and ‘smooth’ tyres. Although aquaplaningtself is not regularly identified, conditions may oftenxist where a high proportion of tyre/road contact is lost.

.5 Because of the effects of weight transfer whenraking and/or cornering some wheels are likely to skidarlier than the skidding resistance of the road surfacelone indicates. In addition, if brakes are out ofdjustment and hence the distribution of braking effortn the wheels is uneven, the minimum skiddingesistance required to avoid skidding will be increasedtill further, as more of the retarding force will have toe taken by the wheels of the functioning brakes.

ICRO-TEXTURE

.6 The micro-texture characteristics of a particulartone depend on its polishing susceptibility under thection of tyre forces.

easurement

3.7 The accelerated polishing machine (Figure3.2) is used on aggregates to simulate the polishingaction of traffic. The Polished Stone Value (PSV)test, which is specified in BS812, requires 6 hoursof polishing designed to produce a state similar tothat which the aggregate would be subjected tounder actual traffic when equilibrium conditions arereached.

3/1


3


F

F

te

leed

.

le

IGURE 3.2 Accelerated Polishing Machine

3.8 The portable skid-resistance tester (Figure3.3) is used to determine the skid resistance valueof the aggregate after polishing. This is termedthe Polished Stone Value (PSV).

IGURE 3.3 Portable Skid Resistance Tester

/2

3.9 Aggregate durability is measured by theAggregate Abrasion Value (AAV) test as definedin BS812. The AAV is a measure of thedurability or resistance to abrasion of anaggregate under the action of traffic.

Aggregate Selection

3.10 To determine the correct PSV and AAV for aparticular site the designer should have regard to theextent and scale of the work. When specifying a PSV itis undesirable to have too frequent changes of aggregaand the aim should be to specify and provide the mosteconomical aggregate available over the longest possiblengths. The highest PSV aggregates should be restrictto those locations where they are required such as onbends and gradients, and at intersections and junctions

3.11 The minimum PSVs to be applied todifferent categories of site and related to trafficflow are given in Table 3.1. The appropriateAAVs are given in Table 3.2. Tables 3.1 and 3.2refer to both new works and maintenance andvalues of PSV and AAV shall be inserted into theappropriate part of Appendix 7/1 of theSpecification (MCHW1). The minimum values ofPSV given in Table 3.1 are the values to be usedif no other information is available. On anexisting site, if the life that has been achieved bythe aggregates, the skid resistance and theskidding accident rate have all been satisfactory,then the continued use of the same aggregatesource, albeit with a lower PSV than that givenin Table 3.1 may be considered. If however, themeasured skid resistance of the site when relatedto the life achieved and the skidding accidentrate are below expectations for an aggregatefrom a particular source, then a higher PSV thanthat given in Table 3.1 may be specified.

3.12 Although some lengths of motorway are carryingtraffic volumes in excess of 6000 commercial vehiclesper lane per day, PSVs in excess of those shown in Tab3.1 should not be specified. Where blank spaces havebeen left in Table 3.1 it is considered that such trafficflows in these locations will not be achieved.

February 1999



24

al

IL Default Site Traffic (cv/lane/day) at design lifeBand IL Categories

Site 0- 251- 501- 751- 1001- 2001- 3001- 4001- 5001- OverDefinitions 250 500 750 1000 2000 3000 4000 5000 6000 6000

I 0.35 A,B Motorway (mainline), 50 50 50 50 50 55 60 60 65 65Dual carriageways(non-event)

Ia 0.35 A1 Motorway mainline, 50 50 50 55 55 60 60 65 65 65300 m approaches tooff-slip roads

II 0.40 C,D Single carriageways 50 50 50 55 60 65 65 65 65 68+(non-event), dualcarriagewaysapproaches to minorjunctions

III 0.45 E, F, Single carriageways 55 60 60 65 65 68+ 68+ 68+ 68+ 70+G1, H1 minor junctions,

approaches to andacross major junctions,gradients 5-10%>50m(dual, downhill only),bends <250m radius>40mph

IV 0.50 G2 Gradients >50m long 60 68+ 68+ 70+ 70+ 70+ 70+ 70+ 70+ 70+>10%

V 0.55 J,K Approaches to 68+ 68+ 68+ 70+ 70+ 70+ 70+ 70+ 70+ 70+roundabouts, trafficsignals, pedestriancrossings, railwaylevel crossings andsimilar

VI 0.55 (20 L Roundabouts 50- 55- 60- 60- 60- 65- 65-km/h) 70+ 70+ 70+ 70+ 70+ 70+ 70+

VII 0.60 (20 H2 Bends < 100m 55- 60- 60- 65- 65- 65- 65-km/h) 70+ 70+ 70+ 70+ 70+ 70+ 70+

Notes: 1. Where ‘68+’ material is listed in this Table, none of the three most recent results from consecutive tests relating to theaggregate to be supplied shall fall below 68. See Paragraph 3.21.

2. Throughout this Table ’70+’ means that specialised high-skidding resistance surfacings complying with MCHW1 Clause 9will be required.

3. For site categories L and H2, a range is given and the PSV should be chosen on the basis of local experience of materiperformance. In the absence of other information, the highest values should be used.

4. Investigatory Level (IL) is defined in Chapter 3 of HD 28 (DMRB 7.3.1).

Table 3.1 Minimum PSV of Chippings, or Coarse Aggregate in unchipped surfaces, for new wearing courses

February 1999 3/3



Traffic (cv/lane/day) <250 251- 1001- 1751- 2501- >3250at design life (see 3.15) 1000 1750* 2500 3250

Max AAV for chippings 14 12 12 10 10 10for hot rolled asphalt andsurface dressing, and foraggregate in slurry andmicrosurfacing systems

Max AAV for aggregate 16 16 14 14 12 12in thin wearing coursesystems, exposedaggregate concretesurfacing and coatedmacadam wearing course

Note 1: For roads carrying less than 1750 cv/lane/day, aggregate of higher AAV may be used where experience hasshown that satisfactory performance is achieved by an aggregate from a particular source.

Note 2: The maximum AAV requirement for porous asphalt is specified in Clause 938 of the Specification (MCHW 1).

gregates in unchipped surfaces, for new

han

TABLE 3.2 Maximum AAV of chippings, or coarse agwearing courses

3.13 The PSVs in Table 3.1 are related to theinvestigatory levels (IL) for different traffic flows set outin Chapter 3 of HD 28 (DMRB 7.3.1). A margin ofsafety has been added for each of the followingreasons:-

a) To allow for variability of aggregates, theprecision of the PSV test and variations inestimating traffic flows;

b) To allow for turning movements and traction/braking forces at major junctions and ongradients;

c) Where possible, to ensure that the skiddingresistance achieved on trunk roads does not fabelow the requirements within the lifetime of thesurfacing. This avoids frequent maintenance onhigh speed and other trunk roads with consequtraffic delays.

NOTE: Investigatory levels for bends (H2) androundabouts (L) are higher than for thecorresponding sections of the same road systembecause MSSC readings at 20kph are higher tthose measured at the standard 50kph for thesame type of surface.

3/4

ll

ent

3.14 Using the appropriate PSV for a particular siteand traffic loading should result in a surfacing givingsatisfactory performance before reaching theinvestigatory level of Mean Summer SCRIMCoefficient. See Chapter 3 of HD 28 (DMRB 7.3.1)..

3.15 The traffic flow used to determine theappropriate PSV and AAV for a particularsurfacing shall be the maximum volume of trafficmeasured as commercial vehicles per lane perday (cv/lane/day) based on the Average AnnualDaily Flow (AADF) calculated to be using thelane at the end of the anticipated life of thesurfacing - see HD 24 (DMRB 7.2.1). Estimatesof traffic growth rates and life of the surfacingmay be based on local experience.

February 1999



3.16 The same levels of PSV and AAV shall beused on different traffic lanes across thecarriageway and in the hardshoulder except that,where aggregates are used for demarcation, amaximum difference of 5 PSV points may beallowed.

3.17 The PSVs given in Table 3.1 apply toroads constructed within current designstandards, and will provide satisfactory skiddingresistance on sites of average difficulty within thegeneral site category for the life of the surfacing.There may be instances where, because of specialdifficulties or departures from standard layoutdesigns, it will be necessary to increase the ‘riskrating’ of a site in accordance with the methodgiven in paragraphs 3.42 to 3.53 of HD 28(DMRB 7.3.3) and hence utilise an aggregate ofhigher PSV.

3.18 For site categories L and H2 ranges of PSV areset out in Table 3.1. The PSV to be specified should beselected on the basis of local experience of materialperformance. For maintenance resurfacing, the currentskid resistance in relation to the life achieved and theskidding accident rate should be considered. Ifsatisfactory, the PSV and AAV of the new surfacingaggregate should be the same as the aggregates usedpreviously. If considered unsatisfactory, the PSV shouldbe increased within the range given for the appropriatetraffic level. For new construction, existing sites withsimilar traffic flows, site geometry and visibility shouldbe used to assist in determining the initial values of PSVand AAV to be specified. In the absence of any suchsuitable information, the highest value in the rangeshould be specified.

February 1999

3.19 The actual PSVs, AAVs and texture depthsbuilt into schemes of new construction and theassumptions on which the minimum values wereselected shall be recorded and maintained in areadily available form, (eg. the schememaintenance manual). Standards to be adoptedin subsequent renewal work may then bedetermined in the light of the skidding resistanceperformance set against those initial recordedvalues.

3.20 The requirements of Tables 3.1 and 3.2cover:-

a) Chippings for surface dressing.

b) The coarse aggregate in thin wearingcourse systems, porous asphalt, bitumenmacadam wearing courses and wearingcourses of rolled asphalt and dense tarsurfacing without coated chippings appliedto the surface;

c) Coated chippings applied to the surface ofrolled asphalt, to mastic asphalt and to finegraded macadam;

d) Coarse aggregate in slurry surfacing andmicrosurfacing systems;

e) The coarse aggregate in non-surfacedressed basecourses of bitumen macadamor stone mastic asphalt and roadbases ofbitumen macadam or rolled asphalt usedas temporary surfaces by general trafficfor prolonged periods and not subject tospeed restrictions or without warningsigns;

3/5



ond to

tgvily

e with

he

sse aceo

eite.

herent are

id

al

gate

3.21 Samples of the chippings representative ofthose to be incorporated into the works shouldbe tested in accordance with BS812 forcompliance with the specified PSV and AAVproperties. Alternatively, except where a PSV of68+ is specified, the aggregate shall be deemed tocomply if the mean of the 3 most recent resultsfrom consecutive tests, relating to the material tobe supplied, is greater than or equal to thespecified PSV and less than the specified AAV.Where a PSV of 68+ is specified, none of thethree most recent results from consecutive testsshall be less than 68. Tests must have beencarried out in the previous 6 months by alaboratory accredited by NAMAS for these testsor by a laboratory in a member state of theEuropean Community (other than the UK) whichcan demonstrate suitable and satisfactoryevidence of technical and professionalcompetence and independence for such tests. Thelatter requirement shall be satisfied if thelaboratory is accredited in a member state of theEuropean Communities in accordance with therelevant par ts of EN45000 series of standardsfor the tests carried out.

3.22 It is essential that the chippings supplied tosite shall be the same in all respects to the samplesubmitted for acceptance. If it is considered thatthere is a change in the material delivered to site,fresh tests shall be ordered.

3.23 There are few quarries which can supplychippings whose PSV is consistently over 68 togetherwith a maximum AAV of 10. In order to achieve valuesin excess of this, it is necessary to specify a resin-basehigh friction surface treatment as described in Clause924 of the Specification (MCHW1). Although highlyskid resistant, material complying with Clause 924 isunable to meet the requirement of a texture depth of1.5mm (measured by the sand patch test), therefore ohigh speed roads this type of material should only beused where strictly necessary eg. for braking sectionsand tight curves. When such materials are to be used high speed roads, attention should be given to the needrain water off the surface by profiling or by othermeans.

3/6

d

n

3.24 The PSV of 70+ is considered to be the highespractical level that can be consistently achieved usinartificial aggregate such as calcined bauxite. For heastressed sites the use of a small size, hard aggregata PSV of 70+ effectively increases the initial skiddingresistance provided and thereby extends its ‘life’, ie. tperiod before the investigatory level is reached. Thiseffective increase in skidding resistance also increasethe stress on the chippings, hence the necessity to ubinder modified with an epoxy or a similar resin. Adviis given in Chapter 9 of HD 37 (DMRB 7.5.2) and alsin Series 900 of the Notes for Guidance to theSpecification (MCHW2).

3.25 To decide whether a high PSV stone should beused for renewing a surface, consideration should begiven to the PSV and AAV of the existing aggregate inrelation to the life achieved, the current skid resistancof the surface and the skidding accident rate of the sIf all are satisfactory, the use of stone from the samesource and of the same PSV may be appropriate. Wrecords of PSV and AAV are not available, identificatioof the source of an aggregate may enable values thasufficiently accurate for assessment purposes to beestimated.

MACRO-TEXTURE

3.26 Adequate macro-texture is required for the rapdrainage of surface water from the tyre and roadpavement interface thereby reducing the chance ofaquaplaning. The texture depth is a measure of themacro-texture and is an important factor influencingskidding in wet conditions on high speed (>90km/h)roads.

3.27 Surface texture takes two forms:-

a) ‘positive’ texture: a cluster of angular peaks orseries of ridges above a datum level, typical ofsurface dressings, rolled asphalt, slurry andmicrosurfacings and brushed concrete;

b) ‘negative’ texture: a network of depressions orseries of grooves below the general level, typicof thin wearing course systems, macadamsurfacings, porous asphalt and exposed aggreconcrete surfacing.

February 1999



e

3.28 Ideally, choice of an appropriate texture depthwould be made on the basis of values related to accidenoccurrence which could then become part of amaintenance policy. However, until research results areavailable, the approach is to specify minimum levels oftexture depth for new high-speed roads to apply atconstruction or major maintenance. This is given inSeries 900 and 1000 of the Specification (MCHW1).

3.29 For speeds in excess of 90km/h the texture depthof the surface should be that required by theSpecification (MCHW1). This will ensure that the skidresistance is maintained and facilitate the rapid drainagof water from the road surface. At lower speeds, texturedepth is less important and compliance with the moregeneral specification requirements or with specified rateof spread of chippings should be sufficient. With lowerspeed roads, micro texture is the major factor inmaintaining skid resistance, although texture is stillimportant. In bituminous and exposed aggregateconcrete roads, micro texture is provided by the use of surface aggregate with a specified resistance to polishingiven by the Polished Stone Value (PSV).

Measurement

3.30 For many years texture depth has been measuredby the ‘sand patch’ method in which a known volume ofsand is spread into a circular patch. The diameter of thepatch is measured and the average depth under the peain the surface calculated. This is the specified referencemethod and advice on the measurement of surfacetexture is contained in the Notes for Guidance to theSpecification (MCHW2).

3.31 More recently laser-based techniques havebecome available which determine the texture depthalbeit by a different methodology.

Mini- Texture Meter (MTM)

3.32 The MTM (Figure 3.4) consists of a laser sensormounted in a special two-wheeled hand propelled trolley,with a micro-computer and printer mounted in thehandle. The machine is operated at walking pace by onperson, can be operated on hot, newly laid surfacingsand is an ideal tool for obtaining results within hours ofcompletion. A special sensitivity mat is required tocalibrate the unit before use on new surfacings. Themachine should also be calibrated against the reference‘sand patch’ method for any particular surface inquestion. The equipment is not suitable for long distanchigh speed surveys and was developed to monitor

clf

T

3liTMdE(aSo

M

H

3wfTacgcEhi

S

3avtssw(

February 1999

t

e

s

ag

ks

e

ompliance with texture depth requirements for newlyaid surfacing. Further details are contained in the Notesor Guidance (MCHW2).

he measurement of texture at high speed

.33 It is possible to measure texture indirectly usingasers at speeds up to 100km/h. This method has beenncorporated in a number of devices; the High Speedexture Meter (Figure 3.5), the High Speed Roadonitor (HRM) and the SCRIMTEX. The HRM isescribed more fully in HD29 (DMRB 7.3.2) Inngland, the Highways Agency research tool HARRIS

Highways Agency Road Research Information System)nd the planned replacement for the HRM, Trafficpeed Condition Surveys (TRACS) use a similar systemf reflected light to determine texture depth.

ATERIAL CHARACTERISTICS

ot Rolled Asphalt

.34 This material has historically been the mostidely used surfacing on trunk roads. The texture is

ormed by rolling coated chippings into the asphalt mat.his technique requires good site control procedures tochieve the correct combination of rate of spread ofhippings and compaction. If the spread rate is too high,ood initial texture is obtained but rapid loss ofhippings can occur when the road opens to traffic.mbedment of chippings may occur if the material is tooot when rolled or rolling is poorly controlled resulting

n low texture depth.

urface Dressing

.35 This technique is widely used throughout the UKnd is a cost effective maintenance treatment. It providesery high initial textures reducing gradually as theraffic causes embedment of the chippings into theurface. This reduction in texture should notignificantly affect the skidding resistance values of aell designed system and textures in excess of 1.5mm

sand patch method) should normally be maintained.

3/7



FIGURE 3.4 Mini-Texture Meter (MTM)

FIGURE 3.5 High Speed Texture Meter (HSTM)

February 19993/8



e

t

d

ell

,

d

Thin Wearing Course Systems

3.36 Thin wearing course systems or thin surfacings asthey are more commonly known, are proprietarysurfacing systems and are coming into widespread use.They are fast to lay and quieter than either hot rolledasphalt, conventional surface dressing or brushedconcrete surfaces. Hot, paver laid thin surfacingscomprising specifically graded aggregates mixed withbitumen binder, customarily modified with polymer orfibre, to generally achieve, after compaction, significantnegative texture. The aggregates form a skeletalstructure providing good resistance to deformation, buttheir grading has to be carefully controlled to avoid theclosing up of voids and consequent loss of texture. Asthin surfacings are proprietary products requiring BBAHAPAS certification, a two year warranty includingtexture retention in the wheeltracks is required.

Macadams

3.37 Most coated macadam mixes are a combination odifferent size aggregate particles mixed with binder andformed into a mat to give a new running surface. Thesurface texture is provided by the small intersticesbetween adjacent aggregate particles and tends to below. Macadams are therefore rarely used for the surfaceof high speed roads.

Porous Asphalt

3.38 Porous Asphalt has been developed with theobjective of reducing spray and has the added advantagof reducing running noise. It is designed to providedrainage through the body of the material therebyreducing the amount of surface water and hence spray.Porous Asphalt consists largely of a single-sizeaggregate held together by binder with interconnectingvoids (giving high texture depth) through which watercan pass. It acts like a sponge until it is almost saturateand then, providing the cross-falls have been designedappropriately, as a lateral drain. It is laid as the wearingcourse of the pavement structure with an impermeablebasecourse layer below it in order to protect the lowerlayers of the pavement from ingress of water.

B

3daaa

3pothasto

3lopwosdarotrthlostogaapSlibs

3bmbeTs

February 1999

f

f

s

e

d

rushed Concrete Surfacing

.39 The skid resistance of a brushed concrete roadepends upon the type and depth of the surface texturend the resistance of the aggregates, particularly the finggregate, in the surface of the slab to polishing andbrasion.

.40 Natural sands having a high silica contentroduce concrete with a higher skid resistance than dother fine aggregates. In particular it has been found thae amount of acid-soluble material in the fine aggregate

ffects the skid resistance of the concrete road, high aciolubility associated with low resistance being attributed the presence of limestone in the fine aggregate.

.41 The reduction of skid resistance to undesirablyw values results from the loss of surface texture andolishing caused by the action of traffic. The rate athich this occurs is largely proportional to the amountf traffic using the road. The skid resistance of wornurfaces can be improved by the application of a surfacressing or a suitable thin wearing course system. Smareas can be treated by grooving or mechanicallyughening the deficient areas. When selecting aeatment, due consideration should be given to the coste effect on traffic while work is in progress and theng term effectiveness of the treatment. Groovedurface textures are long lasting and durable. In addition providing good high speed skidding resistance,rooves sawn at right angles to the direction of travelssist in the effective drainage of surface water, preventquaplaning and considerably reduce spray. A suitableattern of groove spacing is given in Series 1000 of thepecification (MCHW1). Care must be taken in order tomit the volume of noise from such a surface. It haseen found that irregular spacing helps reduce tyre/urface noise.

.42 Improved skidding resistance can also be achievey roughening the worn surface by use of scabbling,illing or abrasive blasting equipment. Abrasivelasting is effective in restoring microtexture andquipment is available for treating large and small areas.he effectiveness of the surface texture produced bycabbling and milling will be influenced by the

properties and characteristics of the coarse aggregate inthe concrete which is exposed. Advice on theeffectiveness of these treatments is given in Chapter 4 oHD 38/99 (DMRB 7.5.3).

3/9



Burlap Drag and Tined Concrete

3.43 An alternative to brushing a concrete surface toachieve transverse texture is a technique called burlapdrag and tine. This has been widely used in America andcan now be used in the UK. The burlap (wet hessian) isdragged over the surface after it has been regulated togive it microtexture. The tined texture is produced usinga head carrying steel tines which is drawn transverselyacross the surface.

Exposed Aggregate Concrete surfacing

3.44 Concrete roads with exposed aggregate surfacesare coming into use for new construction or majormaintenance as they are quieter than conventionalbrushed concrete or hot rolled asphalt surfacings. Thetexture is provided by retarding the hydration of thecement paste in the surface of the road immediatelyfollowing compaction and final smoothing. The retardedsurface layer of cement and fine aggregate is thenremoved by mechanically brushing after the underlyingconcrete has set, to partially expose the surface layer ofcarefully graded coarse aggregate, thus providing therequisite texture.

February 19993/10


Chapter 5Tyre/Road Surface Noise

5. TYRE/ROAD SURFACE NOISE

to

s

e

e

add

GENERAL

5.1 Noise from road traffic has become, over the lasfew years, a very contentious environmental issue.Where traffic speeds are lower than 50 km/hr, trafficnoise is mainly attributable to engine, transmission aexhaust noise, especially from lorries. Where speedshigher, the major component of traffic noise comes fromthe tyre/road interface. This noise comes from, amonother things, vibration of the tyre wall, compression oair within the contact area of the tyre, and the snappout of the tread blocks as they leave the road surfaceThe quality of the road surface, tyre design and vehicspeeds all have an effect on tyre noise.

5.2 Details of the available low noise surfacings anwhere there may be used is given in Chapter 2 of thiPart.

5.3 For many years it has been the UK practice toensure that there are interconnecting drainage pathswithin the surface over which the tyre runs to helpdisperse water and improve skidding resistance,particularly at high speeds. It was also recognised ththe coarseness of the surface contributes to traffic noise.This coarseness has traditionally been measured bysand patch test which gives the average depth of teover an area similar to the contact patch of a tyre.

Definitions of Texture Depths

5.4 It is now recognised that there are a number offactors within the road surface texture that playsignificantly different roles in improving skiddingresistance and generating noise. It is helpful todistinguish different scales of texture by defining theroles of the texture ranges as follows:-

i) The fine scale microtexture of the surfaceaggregate is the main contributor toskidding resistance and is the dominant factor indetermining skidding resistance at lower speeds.

February 1999

t

nd are

gstfing.le

ds

at

thexture

ii) Macrotexture provides rapid drainage routesbetween the tyre and the road surface and contributes the wet skidding resistance at higher speeds. It alsoallows air trapped beneath the tyre to escape.

iii) Megatexture at a scale comparable with the tyrecontact patch is mainly associated with tyre noise.Surfaces with high mega-texture include HRA with gapbetween groups of chippings and the old-style cobbledsurfacings.

iv) Unevenness in the longer ranges cause large tyreand suspension movements that affect the handling ofvehicles.

5.4 Fig 5.1 shows the difference between micro-,macro-, and mega-texture lengths and depths.

5.5 The texture depth is the average deviation of aroad surface from a true planar surface within anycategory of texture. It is represented at the road surfacas:-

i) Microtexture

The roughness of the surface aggregate, which isassociated with the crystalline structure of the coarseaggregate and the sand particles in the surface laitancof a brushed concrete surface.

ii) Macrotexture

Represents the height above a road surface of theaggregate chipping (eg for HRA, surface dressing &brushed concrete), or the depth of texture below the rosurface (eg for porous asphalt, thin surfacings, tined anexposed aggregate concrete surfaces, (EACS)).

ii) Megatexture

Represents the degree of smoothness of the surface.

5/1


Chapter 5References

iv) Unevenness

Describes amplitudes of longer wavelengths which affectvehicle suspensions.

Mega-texture length

Macro-texture length

Mega-texturedepth

Macro-texture depthMicro-texture

Chipping

Micro-texturedepth

Micro-texture length

Figure 5.1 Details of texture length and depths

he

n

5.6 The effect of texture on noise and skidding isgiven in Table 5.1.

5.7 With recently developed laser based equipment tdepth of the texture can be measured separately withineach texture range. The objective of modern surfacingtechniques is to reduce the depth of texture in themegatexture range as much as possible, while retaininan adequate depth of macrotexture to provide high speskidding performance. Low speed skidding performancis mainly controlled by the microtexture. The inter-relationship of the effects of different types of texture onskidding resistance and noise generation are shown inFig 5.2.

5/2

he

gede

Positive and Negative Texture Depths

5.8 An important difference between surfaces, whichhas a strong effect on noise generation, is the degree towhich the surface aggregate particles protrude above tplane of the tyre contact patch. Surfaces which areformed by rolling aggregate chippings into the softsurface of an underlying matrix during construction aredescribed as positive texture. Those in which theaggregate chippings are embedded at the surface withithe matrix,

February 1999



Range Texture length Texture depth/ Skidding(mm) noise properties resistance

Microtexture < 0.5 Littl e noise Low speedcontribution

Macrotexture 0.5-10 Deep texture = High speedlow noise

10-50 Low texture = High speedlow noise

Megatexture 50-500 Low texture = High speedlow noise

Uneveness > 500 Suspension noise Ride quality/handling

Table 5.1 Contribution of Texture Depth to Noise and Skidding

a,

is

se

easent

adsre

es

e.

leaving voids which are generally below the plane of thecontact patch, are described as having a negativetexture. For the same texture depth the latter generatemuch less tyre noise. Brushing concrete road surfacesalso produces a positive texture but this process may,unless care is taken, build up unwanted megatexturedepths (see paragraph 5.20 for further details).

5.9 Positive and negative texture types are shown inFig 5.3. Hot rolled asphalt, surface dressing and brushconcrete surfaces are generally considered to bepositively textured whereas porous asphalt, thinsurfacing and exposed aggregate concrete surfaces argenerally considered to be negatively textured.

Aggregate Shape

5.10 The shape of the aggregate particles that areprovided at the surface to provide for skidding resistancalso can have an effect on noise. Particles of a morecubical nature with a lower flakiness index pack betterinto the surface to provide a flatter area on which thetyre can run. At a detailed level it can be seen that thetyre contact is spread more evenly over the contact arewhich in itself reduces the apparent contact patch.Conversely a rougher surface increases the contactpatch, which exacerbates tyre/road noise as the noise relative to the length of the escape path for the trappedair.

February 1999

ed

e

e

5.11 Road surfaces with negative textures, providedthere is sufficient interconnection between the voidsbelow the running surface, reduce the amount of noigenerated by reducing the air pressures within thecontact area. At high speed the compression and relof air trapped under the tyre is a significant componeof tyre noise.

5.12 These observations can be translated intopractical advice for the design and construction of rowith lower noise surfaces. Advice for controlling texturanges is given in paragraphs 5.13 to 5.21.

Microtextu re

5.13 The amplitudes of microtexture for bituminoussurfaces and EACS come from the roughness of thesurface of the coarse surfaces the microtexture comfrom the fine aggregate (sand). High amplitudes ofmicrotexture have a minimal, if any, effect on the tyre/road noise, but provide low speed skidding resistanc

5/3


Chapter 5References

MICRO-TEXTURE MACRO-TEXTURE MEGA-TEXTURE UNEVENNESS

0.0mm 0.5mm 10mm 50mm 500mm

No contribution

High speedLow speed

Low textureLow textureDeep texture

Length

Requirements

Requirements for

Texture

for low noise

Skid Resistance

Smoothroad

Figure 5.2 Effects of texture depths on skidding and noise

POSITIVE TEXTURE

NEGATIVE TEXTURE

Figure 5.3 Details of surface with positive or negative texture

February 19995/4



Macrotexture

5.14 Macrotexture amplitudes on surface dressed andHRA roads come from the space between individualstones. This is a factor of the size and the evenness ofthe stones on the surface of the road. With PA, thinsurfacing and EACS the macrotexture depths aredependant on the shape of the aggregate at the surfacand the voids between adjacent stones. The voidsbetween the stones allow the air and water beneath thetyre to dissipate rather than be trapped. The cubic natuof stone with a low flakiness index enables a flattersurface of stone to be presented at the road surface wthe benefits outlined in para 5.10. Water trappedbetween the tyre and the road causes aquaplaning at hspeed and trapped air causes noise when the pressurereleased. At larger lengths of macrotexture vibrations ina tyre wall, which are a significant cause of tyre noise,are excited. The ideal is to produce a macrotexture withigh depths in the 0.5 to 10mm lengths and low depthsthe 10 to 50mm lengths.

5.15 The texture of traditional concrete roads is formeby transverse brushing the surface of the concrete whilit is still plastic. The aim is to produce an even texturewithout occasional transverse ridges. The bristles formthe macrotexture during the transverse brushingoperation. Too deep a texture depth can be formed bybrushing when the concrete surface is either too wet, thbrush pressure is incorrect or the bristles are of aninappropriate stiffness. A mix that has lost itsworkability or brushes that are clogged with mortar canproduce a shallow texture.

5.16 With EACS, porous asphalt and thin surfacingsthe macrotexture is a function of the packing and size othe surface aggregate. A low flakiness index is specifieto obtain more cubic aggregate which packs closelytogether to produce small voids. In the UK a 10 to 6mmcoarse aggregate with a 1.5mm texture depth has beenselected to provide adequate skidding resistance. InAustria an 8mm maximum sized aggregate was used treduce the macrotexture in the texture range >10mm,and achieve good noise reducing properties. An 8 to4mm sized aggregate with a 1.0mm texture depth isrecommended for lower speed roads ( 90km/hr) wherethe risk of aquaplaning is less than for high speed road

February 1999

e

re

ith

igh is

h in

de

e

fd

o

s.

5.17 Porous asphalt and some thin surfacings havevoids that interconnect with the surface. The voidspermit water to drain to below the running surface of theroad thereby giving these surfaces their spray reducingqualities. Noise entering these voids is to some extenttrapped within the voids. The untrapped noise tends tobe in the lower frequencies which gives these surfacestheir more distinct lower tonal qualities. These surfacestend to reduce both tyre/surface noise and engine/transmission noise.

5.18 With voided surfaces the sand patch test does notgive a true indication of the surface texture, or itspotential lower noise properties, due to the sand partlyentering the voids. The texture is better assessed byusing close proximity laser based systems to determinethe profile at the tyre contact surface. It has been foundthat the noise increases as the hydraulic conductivityreduces, indicating that the less porous surfaces givehigher noise levels. The test for hydraulic conductivitygives an indication of the noise reducing properties ofporous surfaces.

Megatexture

5.19 It has been found that high megatexture depthscause a tyre wall to deflect and vibrate under load. Thisis a major cause of tyre/road noise. Megatexture onHRA surfaces comes from gaps between the groups ofchippings. This can be caused by the way the chipperspreads the chippings. The chipper dispenses chippingsas a series of transverse bands, with the possibility ofgaps between those bands. These gaps are often in thehigh macrotexture to megatexture ranges (> 10mm). IfHRA surfaces are allowed to cool excessively, such thatthe chipping are not properly embedded, high depths ofmacrotexture and megatexture can result.

5.20 Concrete surfaces laid with a slipform or fixedform paver may have megatexture undulations causedby the paver. These arise from the natural irregularitiesof the paver method of working. There are slight verticalmovements in the surfacing whenever the paver stopsand starts, or the machine compensates for levelchanges. The vertical movements of the transversefinishing screed combined with the forward movement ofthe paver can cause regular depressions in themegatexture range. These can be reduced by thelongitudinal oscillating float (super smoother) whichgives the surface a final smoothing.

5/5


Chapter 5References

Conclusion

5.21 When examining the causes of tyre/road noise it isimportant to be aware of the various interacting factors.The aggregate at the surface makes a significantcontribution to both the skidding and noise performanceof the road. The construction techniques, that are underthe control of the contractor, also provide a majorcontribution to the safety and the tyre/noise generated bythe surface.

February 19995/6


6. REFERENCES AND BIBLIOGRAPHY

Chapter 6References and Bibliography

References

Design Manual for Road and Bridges (DMRB):Stationery Office Ltd

HD 24 Traffic Assessment (DMRB 7.2.1)

HD 28 Skidding Resistance (DMRB 7.3.1)

HD29 Structural Assessment Methods (DMRB 7.3.2).

HD32 Maintenance of Concrete Roads (DMRB 7.4.2)

HD 37 Bituminous Surfacing Materials and Techniques(DMRB 7.5.2)

HD 38 Concrete Surfacing and Materials (DMRB 7.5.

Manual of Contract Documents for Highway Works(MCHW) : Stationery Office Ltd.

Volume 1: Specification for Highway Works (MCHW1)Volume 2: Notes for Guidance on the Specification for Highway Works (MCHW2)

1989

BS812: Part 114; “Methods for determination of thePolished Stone Value (PSV)”, BSI.

1990

BS812: Part 113: “Methods for determination ofAggregate Abrasion Value (AAV)”, BSI.

February 1999

.

3)

Bibliography

1970

Road Note 27; “Instructions for using the Portable SkidResistance Tester”, HMSO.

1972

Szatkowski W. S. and Hosking J. R., “The Effect ofTraffic and Aggregate on the Skidding Resistance ofBituminous Surfacings”, LR504, TRRL.

1976

Hosking J. R. and Woodford G. C., “Measurement ofSkidding Resistance: Part II, Factors Affecting theSlipperiness of a Road Surface”, LR739, TRRL.

1998

Roe, P.G. and Hartshorne, S.A., “The Polished StoneValue of Aggregates and In-service SkiddingResistance”, TRL Report 322.

Roe, P.G., Parry, A.R. and Viner, H.E., “High and LowSpeed Skidding Resistance: the Influence of TextureDepth”, TRL Report 367.

1991

Roe, P. G., Webster, D. C. and West, G., “The RelationBetween the Surface Texture of Roads and Accidents”,RR296, TRRL.

1992

Roe, P. G., “Measurement of the Macrotexture ofRoads: Part 3 Development of the Highspeed TextureMeter”, RR297, TRRL.


February 1999 7/1

Chapter 7Enquiries

7. ENQUIRIES

Approval of this document for publication is given by the undersigned:

Quality Services DirectorThe Highways AgencySt Christopher HouseSouthwark Street J KermanLondon SE1 0TE Quality Services Director

The Deputy Chief EngineerThe Scottish Office Development DepartmentNational Roads DirectorateVictoria Quay N B MACKENZIEEdinburgh EH6 6QQ Deputy Chief Engineer

The Director of HighwaysWelsh OfficeHighways DirectorateCathays Park K J THOMASCardiff CF1 3NQ Director of Highways

The Technical DirectorDepartment of the Environment forNorthern IrelandRoads ServiceClarence Court10-18 Adelaide Street V CrawfordBelfast BT2 8GB Technical Director

All technical enquiries or comments on this document should be sent in writing as appropriate to the above.