performance specified thermoplastic road markings and white lines with glass beads to the various new bs en european specifications for road marking materials

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The Idiots' Guide to Highways Maintenance
Copyright © 2000/08, C.J.Summers

BS EN 1871 : 2000 : Road marking materials - Physical properties

This standard covers paint, cold plastics and thermoplastics.

But, because we deal almost exclusively with thermoplastics I will refer only to this type of material.
Tests included in this specification for thermoplastics are :-

1) Test method for determining the alkali resistance of materials
2) Test method for determining the chromaticity co-ordinates and luminance factor
3) Test method for determining the softening point
4) Test method for determining the heat stability
5) Test method for determining the cold impact resistance
6) Test method for determining the indentation value
7) Test method for determining the Tröger wear

Note
All these tests are performance tests, there are no longer any tests on the composition requirements of the thermoplastic, i.e. percentage of binder or glass beads.
But there are requirements for the quality of the glass beads, that will be mentioned later in the text.

BS EN 1436 : 1998 : Road marking materials - Road marking performance for road users

This standard specifies the various levels of performance that can be stated in a contract document which will govern the required quality of the road marking.
It also describes the methods of measuring the various performance characteristics.

This is one of the fundamental differences between the new BS EN standards and the superseded BS 3262.
Using BS 3262, coupled with the authority contract document there was just one level of quality specified for all road situations.
With the new BS EN standards there are a number of levels of quality specified for several road marking characteristics.

The road marking characteristics being :-

1) Reflection in daylight or under road lighting, 3 classes of performance

2) Retroreflection under vehicle headlamp illumination
Classes for dry road markings, 4 classes of performance
Classes for road markings in conditions of wetness, 4 classes of performance
Classes for road markings in conditions of rain, 4 classes of performance

3) Colour
Luminance, 5 classes of performance
Chromaticity, co-ordinates to fall within a defined square on the
chromaticity diagram

4) Skid Resistance
Classes of skid resistance, 6 classes of performance

The option is open to us when preparing the contract document for the authority to specify a minimum level of performance for each of the road marking characteristics for all road marking situations.

It is interesting to note that in articles I have read in magazines supported by the road marking industry the authors do not refer to the failure of a road marking but they refer to it complying with a lower level of performance.

BS EN 1824 : 1998 : Road marking materials - Road trials

This standard gives guidance for conducting road trials for road marking materials intended for use in both permanent and temporary road marking.
Recommendations are given for test sites, for the application of road marking materials on the test sites, for the parameters to be measured, the frequency of the measurements, the method of measurement, and for the presentation of the results in the form of a test report.

The nature of the road layout, weather conditions, traffic and road surface conditions necessary for the trial are all described in this standard.

There are diagrams detailing the pattern of markings needed to ensure a fair comparison of different products tested.

There are detailed "notes" included in the standard that are extremely relevant to the application of road markings, and I will quote one example.

Clause 6 : Application of road marking materials

6.3 Technical specification for application

Prior to commencement of the road trials, the participating parties should agree upon a technical specification for the application of the road marking material.
NOTE 1 The technical specification for application can include preparation methods (such as how to melt a thermoplastic material), what type of application to use (e.g. extrusion of a thermoplastic material), any particular road marking equipment required, the pattern of application (e.g. plain or a certain type of profile), the rate of application to be applied (in grams per square metre), what drop on materials to add, what rate of application and the method of use.

I hope you will note there is a lot of sound advice given in this note, but who is in charge of arranging and supervising all this, it seems to me it must be the client.

Have we got the time, I think not, but we may have to make time if we want decent road markings under the new specification.
I have been suggesting for some time that a submitted line or lines laid by the contractor at the beginning of a contract is a good idea, the new specification appears to support this idea.

It would seem to me that a trial is necessary to establish a procedure from the contractor to achieve the levels of performance you specify from BS EN 1436.

This would seem to me that what we are establishing is a Method Specification for laying road markings based on performance testing.
The method you establish will be correct while the materials (thermoplastic and glass beads) you use remain the same.
This means that even if you are sure the method remains constant you will still need a regime of performance testing to ensure that the road markings laid conform to the specification in the contract document.

Performance testing procedures included in BS EN 1824 include :-

A) Measurement of the number of wheel passages and the percentage
of HGV's
B) Measurement of texture depth by the sand-patch method
C) Determination of rate of application (thermoplastic and glass beads)
D) Determination of drying time
E) Meteorological determinations
F) Determination of wear index

BS EN 1423 : 1998 : Road marking materials - Glass beads, antiskid aggregates and mixtures of the two

This standard specifies the requirements for laboratory testing and qualification procedures for drop on materials, these materials being glass beads and, if required, antiskid aggregates.

Glass beads will need to comply with the requirements of the specification, after testing, for :-

Granulometry (grading)
Refractive index of the glass
Chemical resistance
Glass bead quality (imperfections of bead shape and gas inclusions)
Surface treatments of the beads, (moisture proof coatings, floatation coatings, adhesion coatings)

Anti-skid aggregates will need to comply with the requirements of the specification, after testing, for:-

Granulometry,
chemical characteristics
friability ( strangely there does not appear to be a polished stone value requirement ) and colour.

The standard describes the methods of test for determining the above properties of glass beads and antiskid aggregate, and mixtures of both.
The method of sampling is also covered in this standard.

BS EN 1424 : 1998 : Road marking materials - Premix glass beads

This standard specifies the requirements for laboratory testing and qualification procedures for the premixed glass beads used in road markings.
The requirements taken into consideration in this standard are :-

Granulometry (grading)
Refractive index of the glass
Chemical resistance
Quality (imperfections of bead shape and gas inclusions)
Surface treatments

Some of the requirements of BS EN 1424 are similar to those of BS EN 1423 and there is common ground between the two specifications, however there is a notable difference between the two specifications with regard to the grading of the beads.
There is a difference between the grading requirements for drop-on glass beads and the grading requirement for premix glass beads.

Note

The issue of glass beads is further complicated by the fact that it states,
"For a period of 5 years after the date of publication of the European Standard existing national standards granulometries can be used."
In this country that means glass beads to the grading requirements of,

BS 6088 : Solid glass beads for use with road marking compounds and other industrial uses

This usually equates to Class A and Class B beads being used for road markings and Class C beads being used for industrial processes.

Class B beads normally being used as the drop on bead.
Class A beads (incorporated in the thermoplastic) are a "bolder" (larger) bead than the medium graded bead of BS EN 1423 ( there is no large graded bead category ), and it is my opinion is likely to give a higher retroreflectivity to a road marking.

However it would be argued that this observation was irrelevant in the new way of doing things as with a performance specification a minimum retroreflectivity would be stated in the contract and it would be up to the contractor to achieve this.
But then, some would argue why do we have a specification for glass beads at all, there must be a reason.
It is quite simple to take a sample of glass beads and have them tested.

Drafts for Development, for Road Marking

The following drafts are not to be regarded as British Standards.

The drafts are meant to be used on a provisional basis so that information and experience of its practical application may be obtained.
They may eventually, after feedback has taken place, become European Standards.

DD ENV 13459-1 : 1999 : Road marking materials Quality control Part 1 : Sampling from storage and testing

This part specifies methods to obtain representative samples of road marking materials for testing and gives the appropriate test methods, i.e. it does not include the test methods themselves but gives reference to the BS EN standard that contains the relevant test method.

DD ENV 13459-2 : 1999 : Road marking materials Quality control Part 2 : Guidelines for preparing quality plans for materials application

Performance of road markings depends not only on the quality of the road markings used, but also on the quality of the application process.
Achieving an appropriate quality for the application process requires the preparation of a quality plan.
This European Pre-standard provides guidance for the preparation of quality plans for the application of road markings.
I do not like accepting Q.A. procedures as proof that a process or material will be of the required quality, because the Q.A. procedure is rarely adhered to in practice.
However this pre-standard does contain a wealth of common sense procedures for ensuring a quality product if only they were actually put into practice by the contractor.

This pre-standard is well worth a browse.

It might also be appropriate to require a Quality Plan to be submitted from the road marking contractors as part of the contract document, at least we would know how the contractor was supposed to be working, and could be monitored.

This requirement could be part of a Best Value submission.

DD ENV 13459-3 : 1999 : Road marking materials Quality control Part 3 : Performance in use

This European Standard describes methods for the quality control of road marking performance for road users, and for the geometry of road markings.
The pre-standard suggests statistical methods of obtaining a representative assessment of the quality of the road markings.
The statistical methods in this document seem unduly complex, and I feel most highways maintenance staff would have to spend some time studying the procedures before they were understood, and that includes me.

TRL REPORT 121 - Laboratory testing of road-marking materials

This is a report on procedures being developed for the laboratory testing of road marking materials to replace the on site trials.
The performance tests described in this report ensure each product being subject to exactly the same testing regime, and without the vagaries of site layout, laying conditions and weather affecting the results.

The testing regime is being developed to include laboratory tests on :-

Erosion (Wear Index),
Rate of spreading of laid line,
Skid Resistance Value,
Luminance Factor,
Retro-Reflectivity,

The report contains very useful information on the above characteristics, and is recommended reading.

National Highways Sector Schemes for Quality Management in Highway Works No.7, Application of Road Marking Materials and Road Studs to Road Surfaces

Published by the United Kingdom Accreditation Service on behalf of the Sector Scheme Advisory Committee for Application of Road Marking Materials and Road Studs to Road Surfaces

UKAS, 21 - 47 High Street, Feltham, Middlesex, TW13 4UN
Tel. 020 8917 8418 : Fax. 020 8917 8400 : Website www.ukas.com

Those participating in the development of the sector scheme are :-

BM TRADA Ltd., - BSI Quality Assurance, - CSS, - DETR-Central Transport Group (CTG), DETR-Highways Agency (HA), - Lloyd's Register Quality Assurance Ltd., - Local Government Management Board (LGMB), - NQA Ltd., - Premier Assements Ltd., - Road Safety Markings Association (RSMA), - SGS Yarsley ICS Ltd., - Society of Chief Officers of Transportation in Scotland (SCOTS)

Reference to all Sector Scheme Documents for Highway Works can be found on the following website, and can be purchased from the site.

UKAS, United Kingdom Accreditation Service --------> www.ukas.com

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