Technical
Report No 2
BBA/HAPAS Approved High-Friction Surfaces
Issue 1, 19-08-02
A study of the visual condition of BBA HAPAS
High-Friction Surfacing (HFS) Sites
Date of issue: December 2015
British Board of Agrément
Bucknalls Lane, Watford, Hertfordshire WD25 9BA
[email protected] T 01923 665300
www.bbacerts.co.uk © 2015
Page 1 of 13
Preface
The BBA HAPAS scheme for High-Friction Surfacing
(HFS) specifies strict on-site and laboratory
performance requirements for HFS and states that
the expected service life of BBA HAPAS approved
systems is between 5 and 10 years. This statement of
anticipated service life has led to an increase in
confidence in the capabilities of these products and
an increase in their use as an anti-skid measure on
roads at high-risk sites throughout the UK.
Despite the success of HFS there has been debate
on whether the visual appearance of different
generic types, particularly thermosetting and
thermoplastic, is a reflection of their service life. In
order to begin the process of addressing these
concerns, the BBA undertook a study of the visual
condition of installed BBA HAPAS Certified HFS
systems. The study had four main objectives:
● to include and inspect only those HFS sites which
are traceable to BBA HAPAS approved installers
and the BBA HAPAS approved systems
● a
ward a rating to each based on a visual
assessment of surface condition
● to use the information from each visual
assessment to provide supporting data for the
estimated service life
● to analyse the data obtained to determine
whether or not there are significant differences
between the service lives of the different generic
types of HFS.
This report provides details of the study and
summarises findings based on our visual condition
inspections completed over a two year period from
2013 to 2014.
Key Findings
● U
sing a base line visual condition rating of
‘Acceptable’ a service life of greater than five
years is reasonable irrespective of generic type
● O
f a total of 304 inspections covering 272 sites,
87% achieved this ‘Acceptable’ mark or better;
only 14 sites less than five years old were rated
below this, and nine of these had defects which
were not attributable to the system itself
● S ubstrate type, condition and preparation at time
of installation has the greatest impact on the mark
awarded and eventual service life of the
surfacing
● W
inter installations (Oct-Mar) resulted in a greater
incidence of sites marked as ‘Moderate’ as
opposed to ‘Good’ for summer installations
(Apr-Sept)
● B
BA-witnessed site installation marked slightly
higher than sites which were not witnessed
● T hermoplastic systems were generally marked as
moderate to good, whereas Thermosetting
systems tended to be marked as good to
excellent
● In order to provide definitive indications of service
life, monitoring of sites should be continued to
include
– more sites which are older than five years
– m
easurement of surface texture depth and
skid resistance, particularly to determine
whether the difference in visual condition is a
reflection of an adverse effect on these aspects
– m
onitoring of sites to the end of their life to
determine their actual in-service life.
Page 2 of 13
Introduction
The British Board of Agrément (BBA) has operated
the Highway Authorities Product Approval Scheme
(HAPAS) for HFS since 1996. During that time, the BBA
has issued 20 Certificates covering four main
generic types of high friction material:
● Thermoplastic types 1-3
● Epoxy types 1-3
● Polyurethane types 1-3
● MMA types 1-3.
All have been assessed and approved using end
performance criteria from the BBA HAPAS Guideline
for the Assessment and Certification of High Friction
Surfacing for Highways. This was developed with
input from a specialist technical group (SG1)
consisting of a broad representation of industry
bodies including:
● t he Association of Directors of Environment,
Economy, Planning and Transport (ADEPT)
(previously known as the County Surveyors
Society)
● the British Board of Agrément (BBA)
● the Highways Agency (HA)
● t he Road Safety Markings Association (RSMA)
(incorporating the Road Safety Surfacing
Association)
● t he Road Surface Treatments Association (RSTA)
(previously represented by the High Friction
Surfacing Association (HFSA))
The BBA study and its scope
The study consisted of an assessment of the visual
condition of installed surfaces only. The inclusion of
any physical testing or assessment was not possible
within the resource allocated. The sites selected
were collated from BBA-led inspections completed
as part of the BBA’s routine five-year performance
reviews and sites identified from our database of HFS
installer inspections. The total of 304 inspections
covered 272 different locations throughout the UK.
The site ages ranged from 12 months to 14 years.
The visual inspections recorded information on
surface condition and installation, such as:
● installer details
● details of Certificate holder
● age of installation
● site location
● site category
● substrate type
● substrate condition
● substrate colour
● generic substrate type
● details of defects
● miscellaneous observations
● mark awarded
● whether the surface has been overlaid/replaced
● the Transport Research Laboratory (TRL).
● w
eather conditions during installation and
inspection.
A BBA Certificate of approval for HFS (examples of
which can be found on the BBA website at www.
bbacerts.co.uk) is awarded upon satisfactory
completion of a six stage process which includes:
Based on these observations, a mark was awarded
in accordance with Appendix F of the BBA HAPAS
Guideline, which grades surfaces on the following
scale:
1) assessment of Applicant’s data
2) assessment of factory production control
3) laboratory testing (and optional tests)
4) a system installation trial
5) a system performance trial (if applicable)
6) certification.
The HFS is given a level of approval (1, 2 or 3) based
upon traffic levels (commercial vehicles per lane per
day, expressed as cv/l/d) and site categories as
1) Excellent
2) Good
3) Moderate
4) Acceptable
5) Suspect
6) Poor
7) Bad.
defined in the Design Manual for Roads and Bridges
(HD 28/04).
Page 3 of 13
Figure 1 Examples of sites inspected and ratings*
A51 Tamworth — Good
C42 St Helens — Excellent
A628 Barnsley — Moderate
Grainger Drive — Suspect
A615 Wessington — Acceptable
Vicarage Rd Catterick — Poor
A4 Reading — Bad
Analysis of site data
Chart 1 identifies the proportion of sites examined per generic type. Thermosetting represents 47% and Thermoplastic 54%
of the total sites inspected and marked. The high percentage of Thermo Type 1 is considered typical of this type’s market
share and is reflective of our own records related to sampling frequency.
Chart 1 Proportion of inspections per generic type
60%
50%
40%
30%
20%
10%
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Page 4 of 13
Chart 2 shows the percentage of marks awarded per category for all sites inspected. Some 87% of sites inspected were
considered better than or equal to ‘Acceptable’ in terms of their visual condition.
Chart 2 Marks awarded for all types
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
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Charts 3a and 3b show that the thermosetting had a higher percentage of ‘Excellent’ and ‘Good’ markings compared
with thermoplastic which marked slightly more towards ‘Good’ and ‘Moderate’. Both generic types clearly show that the
majority of sites were ‘Acceptable’ or above in terms of their visual condition.
Chart 3a Marks awarded — Thermosetting
Chart 3b Marks awarded — Thermoplastic
60%
60%
50%
50%
40%
40%
30%
30%
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Page 5 of 13
Charts 4a and 4b show the marks awarded for winter and summer installations across all generic types. There is a
noticeably higher incidence of ‘Good’ marks awarded to sites installed in the summer.
Chart 4a Winter (Oct-Mar) installations — all types
Chart 4b Summer (Apr-Sep) installations — all types
60%
60%
50%
50%
40%
40%
30%
30%
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20%
10%
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Charts 4c and 4d show marks awarded for thermosetting and thermoplastic sites installed in the winter. The majority of
thermosetting sites received a ‘Good’ rating whereas the majority of thermoplastic sites were marked as ‘Moderate’.
Chart 4c Winter installed thermosetting
Chart 4d Winter installed thermoplastic
60%
60%
50%
50%
40%
40%
30%
30%
20%
20%
10%
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Charts 4e and 4f show the marks awarded for thermosetting and thermoplastic sites installed in the summer. In both cases
the majority of sites received a ‘Good’ rating.
Chart 4e Summer installed thermosetting
Chart 4f Summer installed thermoplastic
60%
60%
50%
50%
40%
40%
30%
30%
20%
20%
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Page 6 of 13
Charts 5a and 5b show the marks awarded across all generic types for sites where BBA Inspectors were and were not
present at the time of installation. Whilst the majority of sites were marked ‘Acceptable’ or above (regardless of BBA
presence) there was a higher incidence of sites marked ‘Good’ when the BBA was present.
Chart 5a Sites witnessed by BBA Inspection
Chart 5b Sites not witnessed by BBA Inspection
60%
60%
50%
50%
40%
40%
30%
30%
20%
20%
10%
10%
0%
nt
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Charts 5c and 5d show the marks awarded for thermosetting systems for sites where BBA Inspectors were and were not
present. The ‘Good’ marking was noticeably higher in installations witnessed by the BBA.
Chart 5c Thermosetting sites witnessed by BBA
Chart 5d Thermosetting sites not witnessed by BBA
60%
60%
50%
50%
40%
40%
30%
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Page 7 of 13
Charts 5e and 5f show the marks awarded for thermoplastic systems for sites where BBA Inspectors were and were not
present. As in the case of thermosetting systems, the ‘Good’ marking was noticeably higher in installations witnessed by
the BBA.
Chart 5e Thermoplastic sites witnessed by BBA
Chart 5f Thermoplastic sites not witnessed by BBA
60%
60%
50%
50%
40%
40%
30%
30%
20%
20%
10%
10%
0%
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Charts 6a and 6b show the percentages of marks awarded for each category for the two main colours widely used.
Differences between individual markings across the two colours are minor, with buff and grey having similar ratings.
Chart 6a Performance of grey colour surface
Chart 6b Performance of buff colour surface
60%
60%
50%
50%
40%
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30%
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Charts 6c and 6d show the percentages of marks awarded for each category for each of the colours widely used when
applied just to thermoplastic systems. Differences between individual markings across the two colours are more
noticeable with the grey colour marking significantly higher than the buff colour in the ‘Excellent’ and ‘Good’ markings.
Chart 6c Performance of grey thermoplastic
Chart 6d Performance of buff thermoplastic
60%
60%
50%
50%
40%
40%
30%
30%
20%
20%
10%
10%
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Page 8 of 13
Charts 6e and 6f show the percentages of marks awarded for each category for each of the colours widely used when
applied just to thermosetting systems. Differences between individual markings across the two colours are, again, more
significant than the overall performances but this time, and conversely with thermoplastic systems, the buff colour marks
higher than the grey colour in the ‘Excellent’ and ‘Good’ markings.
Chart 6e Performance of grey thermosetting
Chart 6f Performance of buff thermosetting
60%
60%
50%
50%
40%
40%
30%
30%
20%
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Site observations
Chart 7 summarises additional comments (irrespective of the mark awarded) made by BBA Inspectors during witnessed
installations and subsequent inspections. The observations give a strong indication as to the causes of defects identified or
their potential impact on the visual condition of the surface.
Chart 7 Site observations
Observations
installation temp (high)
over heating
Thermoplastic
Thermosetting
premature cure
substrate
screed line cracking and delamination
0
10
20
30
40
50
60
70
80
90
100
‘Substrate’ on Chart 7 includes observations of defects or the onset of defects as a result of:
● overlays to existing HFS, microasphalt and surface dressing
● post-installation work such as road widening, signal loops and utility reinstatements
Page 9 of 13
● cracks associated with structural or lower layer failure such as crazing or reflective joint cracks
● high texture or open substrates causing drainage of thermosetting binders.
The chart indicates that over 75% of imperfections which led to or will lead to defects are related to the substrate or
post-installation work. The key observation which differentiates between thermosetting and thermoplastic is the visually
apparent cracking and delamination at the screed line on thermoplastic which does not occur on thermosetting
installations.
Estimate of Service Life
For this report the BBA considered any site which was five years of age or older and which achieved a mark of
‘Acceptable’ as indicative of it being able to meet the five year durability as stated in the approvals. In order to provide
some indication to industry, Charts 8a and 8b show the distribution of visual condition for each age of the thermoplastic
and thermosetting generic groups. Chart 8a shows the linear trends of distribution with all the data available and Chart
8b shows the effect of removing sites where non-system related issues have been observed that may affect the service life
of the system.
Chart 8a Distribution of visual condition for each age of sites
7.00
Condition (4 = acceptable)
6.00
All
5.00
Thermoplastic
4.00
Thermosetting
R2 = 0.6331
3.00
Linear (all)
2.00
Linear
R2 = 0.5906
(Thermoplastic)
Linear
R2 = 0.6487
(Thermosetting)
1.00
0.00
0
2
4
6
8
10
12
Years
Page 10 of 13
Chart 8b Distribution of visual condition for each age of site excluding those with observed defects/
potential failures
Condition (4 = acceptable)
7.00
6.00
All
5.00
Thermoplastic
4.00
Thermosetting
3.00
Linear (all)
2.00
R2 = 0.304
Linear
R2 = 0.5309
(Thermoplastic)
Linear
R2 = 0.2758
(Thermosetting)
1.00
0.00
0
2
6
4
8
10
12
Years
Chart 8a shows that the sites are achieving an overall visual condition of ‘Acceptable’ (4.0 on the vertical axis) or higher
up to five years in service. It also shows that, overall and on average, thermoplastic sites dropped below the ‘Acceptable’
level after 8 years of service, whereas thermosetting sites took 12 years to reach this point.
Chart 8b removes sites where observations have noted that other factors such as substrate or pre-post installation are likely
to affect the service life of the system. This removes a significant amount of sites from the chart and moves the trend lines
for all systems inspected above the 10 year acceptable level.
Extreme cases
A total of 14 sites were marked as ‘Suspect’ or below
before reaching five years in service. The analysis of
reasons for their failures revealed the following attributable
factors:
Installer-related
● overheating of the binder during installation.
Substrate or site-related
● complete structural failure of the existing roadway
● a
pplication to surface dressing at high ambient
temperature during installation
● installation overlaid onto existing failed HFS
● p
ost-installation work (e.g. road widening/signal loops/
reinstatements).
If the time of year (winter or summer) is taken into account
then it is noted that nine out of the 14 sites were installed
during the winter season.
If we apply factors relating to time of year (winter/summer)
and colour (grey/buff) then all 14 of the extreme sites were
found to have one or more of the contributing factors
associated with a visual condition mark of suspect or less
at five years.
Page 11 of 13
Recommendations and future work
As indicated under ‘Key Findings’ above, the lack of more
comprehensive inspection data means that it has been
necessary to make certain assumptions in order to
complete our analysis. The BBA recognises this deficiency
and will be recommending to SG1 further analysis of
existing sites and adding to the number of sites visited in
order to improve the reliability of future output and
recommendations. Key assumptions which were
necessary in respect of the current analysis were:
● s kid resistance properties remain acceptable,
irrespective of the age of the installation.
● e
ach site was visually classified as Type 1as defined in
the HFS Guideline. However it was noted that the
commercial vehicles per lane per day (cv/l/d) is
variable. Unfortunately there was insufficient resource to
identify this information via traffic surveys or through
contact with the Road Authorities.
British Board of Agrément
The British Board of Agrément (BBA) is the UK’s major
authority offering approval and inspection services to
manufacturers and installers supplying the construction
industry. Originally set up in 1966 by Government, but now
an independent non-profit distributing organisation, the
BBA’s certification and inspection services are recognised
by building control, local authorities, industry insurers and
key trade associations in the construction industry. The BBA
is increasingly engaging in testing and research beyond
Agrément Certification. The work covered by this report is
an example of these activities, but there are others such as
the use of full fill cavity wall insulation in masonry walls at
very severe exposures and the assessment of walls with
partial fill insulation where cavity wall insulation is
subsequently added. Thermal simulation tools are widely
used in further research, with all activities taking place on
the same site and under BBA control.
What do we do?
The BBA provides reassurance to the industry that the
products, systems and procedures are ‘fit for purpose’, as
they have undergone a rigorous and thorough assessment
process. It is continuously investing in its people and test
equipment to further extend its capabilities, and provide a
better service to its customers.
Product Approval and Certification
● Agrément Certificates: The BBA’s premium award,
recognised by key stakeholders in the construction
industry as a robust, impartial and rigorous assessment
of a product’s ‘fitness for purpose’.
● H
APAS Certificates: Nationally recognised approvals for
new products and systems developed especially for
highway use.
● M
icrogeneration Certification Scheme (MCS): A third
party scheme developed by Government to
independently assess manufacturers and installers of
small-scale renewable technologies to documented
standards. The BBA is a notified body under this scheme,
offering MCS certification for products covered by it.
● E
nvironmental Profile Certification: A statement of
characterised data and eco-points per functional unit
of a building element assessed using the BRE
methodology. Additional information such as recycled
content and reference to responsible sourcing can also
be included.
● C
ertificates of Competency: This scheme has been
devised in association with TIMSA (Thermal Insulation
Manufacturers and Suppliers Association) and is used for
assessing and monitoring U-Value and condensation risk
calculation competency. Competent persons are
awarded a unique identification number which they
can use to identify their calculations.
Page 12 of 13
Installer and Inspection Services
The BBA has over 40 years’ experience in providing
independent and unbiased information on products and
their installation. Our inspection teams cover various
activities, ranging from monitoring of BBA Approved
Installers operating under client managed schemes to
surveillance visits carried out on behalf of the Government
endorsed Competent Person and TrustMark schemes. Our
inspection teams cover the whole of the UK including the
Isle of Man, the Channel Islands and Northern Ireland as
well as Eire. They also operate in the USA and China.
Test Services
The BBA’s Test department has supported the Agrément
process by providing test facilities for manufacturers
wishing to gain Agrément approval. Its experience
extends to over 200 different product areas across the
entire spectrum of building products, backed by a wide
range of UKAS accreditations. The department in
increasingly involved in bespoke activities, undertaking
tests against European Standards and new product
development, by using state of the art thermal and
durability testing equipment.
Management systems
The BBA provides registration to BS EN ISO 9001 and
BS EN ISO 14001 either in support of an Agrément
Certificate application or as a stand alone approval for
companies wishing to demonstrate that they have robust
practices and procedures in place.
Recent Developments
● C
E Marking: With the Construction Products Regulation
(CPR) coming into force in July 2013, the BBA has been
involved in the preparation of a Guidance Note on
CPR, to be published by the Construction Products
Association, which explains the implications of this
legislation to the industry.
via the requirements of the Green Deal Installer Installation
Standard (PAS 2030). In collaboration with the BRE it works
to give reassurance to providers that installations will be
carried out in accordance with the Green Deal standards.
● G
reen Deal: This is a Government-backed initiative and
the BBA has been accredited by UKAS to assess installers
Glossary of terms
BBA: British Board of Agrément
HAPAS: Highway Authorities Product Approval Scheme
HFS: High Friction Surfacing
Thermosetting HFS: Cold-applied or broadcast systems
(including mma, polyurethane, epoxy bitumen or resin
extended)
Thermoplastic HFS: Hot-applied systems
Type 1 applies to roads carrying a maximum of 3500
vehicles per lane per day (cv/l/d), type 2 applies to roads
carrying a maximum of 1000 cv/l/d and type 3 applies to
roads carrying a maximum of 250 cv/l/d.
Service life: The period of time during which the
performance of the works will be maintained at a level
compatible with the fulfilment of the essential
performance characteristics.
Type 1-3: Road categorisation according to traffic density,
Type 1 being the highest category and Type 3 the lowest.
British Board of Agrément
Bucknalls Lane, Watford, Hertfordshire WD25 9BA
[email protected] T 01923 665300
www.bbacerts.co.uk © 2015
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