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Transportation Research Procedia 14 ( 2016 ) 869 – 875
2352-1465 © 2016 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of Road and Bridge Research Institute (IBDiM)
doi: 10.1016/j.trpro.2016.05.035
Available online at www.sciencedirect.com
ScienceDirect
6th Transport Research Arena April 18-21, 2016
Sustainability assessment of road marking systems
Marisa Cruz a,
*
, Alexander Klein a, Viviana Steiner a
aEvonik Resource Efficiency GmbH, Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang
Abstract
Environmental issues are becoming increasingly important in the domestic, business and public sectors. Due to population
growth and growing number of megacities, Green Public Procurements concepts is also becoming an increasing trend in the road
infrastructure sector.
This study assessed the environmental impacts of road markings considering the whole life cycle from manufacturing to disposal.
For the correctness of the study, an external expert panel reviewed the assessment. By using the LCA-Methodology based on
DIN ISO 14040 and 14044, an objective comparison of the following line markings was performed: Solvent-borne paint; Water-
-based paint; Thermoplastic and Thermo Spray Plastic; Cold Plastic and Cold Spray Plastic. Typical material formulations in
characteristic application scenarios have been modelled using the data of corresponding official approval test certificates held by
a major local manufacturer of all evaluated technologies. Empirical data was used to determine a typical service life of the
various road marking systems at a typical average daily traffic of 10,000–15,000 vehicles per day.
The life cycle assessment results, i.e. considering the whole life cycle from manufacturing to disposal, showed that a global
warming potential reduction of more than 50% can be achieved by a more durable road marking system.
The study concluded that in order to access the actual environmental impact of road markings, a lifetime evaluation including, for
instance, production, application, transport, service life, and disposal must be taken into consideration.
© 2016The Authors. Published by Elsevier B.V..
Peer-review under responsibility of Road and Bridge Research Institute (IBDiM).
Keywords: Life Cycle Costs; road marking; cradle to grave; cold plastics; durability
* Corresponding author. Tel.: +49 6181 59-5104; fax: +49 6181 59-75104.
E-mail address: marisa.cruz@evonik.com
© 2016 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of Road and Bridge Research Institute (IBDiM)
870 Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
1. Introduction
Environmental issues are becoming increasingly important in the domestic, business and public sectors.
Politicians worldwide are therefore, developing Greenhouse gas emissions reduction targets (EU Action 2015). GPP
guidelines implemented by the European Union, for example, are calling for the consideration of environmental
aspects based on solid scientific evidence when deciding various product alternatives.
Green Public Procurement (GPP) guidelines recommend that public purchasers consider environmental aspects
based on solid scientific evidence when deciding on various product alternatives (GPP 2015). Due to population
growth and growing number of megacities, GPP concepts are also becoming an increasing trend in the road
infrastructure sector.
For instance, horizontal road markings are widely accepted as the only road safety device in the road
infrastructure sector that accompanies drivers throughout their entire journey. Every day millions of road users
worldwide benefit from the efficient and indispensable ability of road markings to provide them with guidance and
protection.
The selection of materials for road markings is traditionally based on technical requirements, climatic and
topographic conditions, traffic density and cost considerations. Environmental aspects might not be considered
properly because of the lack of comprehensive environmental impact data for all major road marking systems.
According to ISO 14040, the Life-cycle assessment (LCA), also known as ecological balance, is a scientific tool
used to assess the environmental impacts of a product throughout its entire life cycle, from cradle to grave. It aids in
process improvement, and supports policies in creating a sound basis for well-founded decisions that involve
environmental considerations.
However, lowering environmental impacts ultimately depends on efforts and decisive actions of governments,
industries and consumers. The aim of this study is to assess the environmental impacts of the major binder-based
road marking systems on the market, in typical formulations and characteristic application scenarios over the entire
life cycle. Main focus of the study will be a comparison of spray road marking, and agglomerate road markings
application scenarios, attention paid to refreshment of expired road markings.
This assessment takes into consideration all contributions from raw materials, production, application, usage, and
disposal or recycling, to all necessary transport, auxiliary and packaging materials.
2. Methodology and scope
The study was conducted in accordance with DIN ISO 14040 and 14044 and reviewed by a panel of external
experts. It was geared toward marking practices in Germany as one of the largest national markings market in
Europe, where all materials technologies are used in significant amounts. The pavement surface of a typical German
federal road bears a moderate average daily traffic of about 10,000–15,000 vehicles and requires renewal
approximately every 10 years. Consequently, in this study, the lifecycle of the marking was evaluated for a period of
10 years.
The four major binder-based marking systems assessed were Solvent-borne (SB) paint; Water-based (WB) paint;
Thermoplastic (TP) and Thermo Spray Plastic (TSP); MMA (Methyl Methacrylate) Cold Plastic (CP) and MMA
(Methyl Methacrylate) Cold Spray Plastic (CSP) also referred to as MMA (Methyl Methacrylate). The road marking
systems consisted of marking material and drop-on material. The following environmental impact categories were
analyzed considering a one-kilometer marked road, using the CML method [CML 2001] of the Institute of
Environmental Sciences (CML) of Leiden University with the updated characterization factors from November
2009:
x Global warming potential (GWP100) [kg CO2-equiv.]
x Acidification potential (AP) [kg SO2-equiv.]
x Eutrophication potential (EP) [kg phosphate-equiv.]
x Photochemical ozone creation potential (POCP) [kg ethene-equiv.]
x Human toxicity potential (HTP) [kg DCB-equiv.]
x Terrestric ecotoxicity potential (TETP) [kg DCB-equiv.]
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Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
x Freshwater aquatic ecotoxicity potential (FAETP) [kg DCB-equiv.]
x Primary energy demand as an additional criterion
For all the systems, the production, including the so-called ecological rucksacks of raw materials and energies up
to the formulator's factory gate (“cradle to gate”), was first analyzed, and the analysis was then extended to the
entire life cycle, considering multiple application of marking on the road, including disposal (“cradle to grave”). The
system comparison was based on typical product formulations in various representative application scenarios
corresponding to the specifications for road markings and the relevant suitability tests for marking systems of the
Bundesanstalt für Straßenwesen (BASt, German Federal Highway Research Institute). In principle, the conclusions
of this study can be carried over to other countries or regions, provided that the performance conditions apply
similarly.
The complete LCI model set up in GaBi 4 with all upstream chains comprises more than 1100 processes, used in
more than 190 plans and subplans.
2.1. Type II marking systems
Type II road markings are distinguished from type I in that they are designed to have especially noticeable
retroreflectivity properties at night and in wet conditions. Agglomerate or Structure markings are known for
providing higher visibility in wet night conditions (Fig. 1). Rainwater drains off freely from the top of the stable 3-D
structure and the glass beads embedded in the marking material are clear to reflect the incoming light of the vehicle.
Fig. 1. Graphic representation of agglomerate marking under wet surface conditions.
2.2. Minimum requirements of night visibility
The performance of a marking is assured if 90% of the marked surface is intact and the minimum values for
traffic-engineering characteristics defined on the European Norm EN 1436:2009-01 are met:
x Dry marking surface, R ≥ 150 mcd /m-2 /lx-1
x Wet marking surface, RW ≥ 35 mcd /m-2 /lx-1
2.3. Functional Unit (FU)
Ecological impact parameters have been evaluated per kilometer of road section marked with two full edge lines
and one broken middle line of 12 cm (4 in) width, amounting to a total marked area of 280 m2 (Fig. 2).
872 Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
Fig. 2. Representation of a federal road section with marking as functional unit (FU).
2.4. Selected reference scenarios based on actual road use situations
2.4.1 Scenario 1: spray applied thin-layer marking, type II
In scenario 1, various type II thin-layer marking systems are compared (Table 1). For the marking types under
consideration, the thin-layer marking systems can be renewed by overmarking with a new spray layer after
expiration of their service life.
Table 1. Main parameters for scenario 1, based on actual road use (specified in ZaTV M 02, DIN EN 13197 and EN 1436).
Material type
CSP type II
TSP type II
WB type II
SB type II
Layer thickness, mm
0.6
1.2
0.6
0.6
Usage of drop-on material, kg/m²
0.60
0.60
0.60
0.45
Lifetime, years
2.5
2.0
1.0
1.0
No. of markings
4
5
10
10
2.4.2 Scenario 2: agglomerate markings (structure markings), including spray refreshment
In scenario 2, Cold Plastic and Thermoplastic type II agglomerate markings are compared. For Cold Plastic,
refreshing of the marking with Cold-Spray Plastic (0.3 mm) is possible because Cold Plastics suffer hardly any
wear. In this scenario, both of the possibilities for Cold Plastic, with and without refreshing are considered. For
Thermoplastics the option of refreshing with a thin spray layer of the same material, is not given because
Thermoplastics are liable to wear. Table 2 summarizes the most important assumptions:
Table 2. Main parameters for scenario 2, based on actual road use (specified in ZTV M 02, DIN EN 13197 and EN 1436).
Material type
Cold Plastic Agglomerate
(Structure)
Cold Plastic Agglomerate
(Structure) + refreshment with
Cold Spray Plastic
Thermoplastic Agglomerate
Application
Stochastic
Stochastic
Regular
Refreshing/renewal with
None
Cold Spray Plastic (0.3 mm)
None
Layer thickness, mm
No indication possible
No indication possible
No indication possible
Material usage, kg/m²
2.8
CP: 2.8 / CSP: 0.47
3.7
Drop-on material, kg/m²
0.40
CP: 0.40 / CSP: 0.30
0.37
Lifetime, years
4.0
4.0 + 3 x 2.0
3.0
No. of markings
3
1x CP + 3x CSP
4
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Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
2.5. Transport routes scenario assumptions
The transportation of the marking substances from the producer to the customer, from the applicator to the
application site, and on the application site itself, and the resources consumed for such transport, were appropriately
considered.
Fig. 3. Transport routes scenario of precursors and marking systems from cradle to grave.
3. Results
The system comparison was based on typical product formulations in various representative application scenarios
corresponding to the specifications for road markings and the relevant suitability tests for marking systems of the
Bundesanstalt für Straßenwesen (BASt – German Federal Highway Research Institute).
The impact indicators results for scenario 1 spray applied thin-layer marking of type II shows a considerable
reduction of environmental impacts provided by Cold Spray Plastics on 7 out of 8 indicators (Fig. 4). This favorable
environment results is highly influenced by the higher durability of Cold Spray Plastics in comparison to Solvent
and Water Based paint. Cold Plastics in general, owes its inherent durability to its duroplastic characteristics. MMA
CP are chemically cured upon addition of a hardener (second component) to form a highly resistant duroplastic Cold
Plastic road marking.
Considerable reduction of photochemical ozone creation potential (POCP) is achieved by TSP, followed by CSP,
and WB systems in accordance with previous report (Ökopol 2011). This is largely a result of the low emission of
volatile organic compounds associated with these technologies. On the other hand, Thermoplastics are solid
materials that must be melted at temperatures of 200 °C to 220 °C (392 °F to 428 °F), which highly determines
energy consumption, and consequently higher primary energy consumption in comparison to CSP. Possible
contributions to POCP, or toxicological impacts of evaporation or volatile decomposition products originated during
the heating process of Thermoplastic have been ignored in this study due to the absence of reliable data.
The impact Indicators for Scenario 2: Thick-layer agglomerate markings, including refreshing confirms the
common sense that the service life of the MMA Cold Plastics can be further prolonged thanks to its inherent
durability. The available agglomerate (structure) pattern can be refreshed by a simple Cold Spray Plastic layer and
broadcasting of new glass beads. This common practice brings back the lost retroreflectivity caused by tire wear
over time, therefore reducing the overall environmental impact of this road marking.
The combination of agglomerate MMA Cold Plastics (structure markings) and refreshment with a thin layer of
MMA Cold Spray Plastics contributes with an outstanding reduction in the overall global warming potential (Fig. 5).
For instance, in a country like Germany, with 645,000 km paved roads, a yearly potential reduction of 297,000 [tons
CO2equivalents] can be achieved in comparison to thermoplastic agglomerates. This corresponds to the greenhouse
gas emissions from 63,000 passenger vehicles per year (Greenhouse 2015).
formulator
raw
materials
energy
waste
applicator
new application
overmarking
/
refreshing
removal
+
new application
material usage
energy
waste
useful life of the asphalt layer
10
years
truck
300
km
area per km
(
(
280
m
²
)
useful life of the marking system dependent
truck
300
km
trailer truck
2
x
150
km
truck
150
km
street cleaner
2
x
150
km
874 Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
Fig. 4. Relative environmental impacts of cold spray plastic (CSP) type II thin-layer markings, sprayable thermoplastic (TSP), solvent-based (SB)
paints and water-based (WB) paints.
Fig. 5. Relative environmental impacts of agglomerate markings including cold plastic (CP), cold plastic refreshed three times with 0.3 mm cold-
-spray plastic (CSP) and thermoplastic (TP) – all values with reference to marking with cold plastic (CP).
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Marisa Cruz et al. / Transportation Research Procedia 14 ( 2016 ) 869 – 875
4. Conclusion
The life cycle assessment results, i.e. considering the whole life cycle from manufacturing to disposal, show that
more than 50% global warming potential reduction can be achieved with a more durable road marking system.
Meaning, global warming potential reduction is possible by adopting an educated choice of material and application
technology considering a whole life cycle perspective.
MMA Cold Plastics in agglomerate form (also known as structure marking, “3D” marking) provide an
environmentally friendly road marking solution. Lower environmental impact is achieved thanks to its inherent
durability and possibility of prolonging service live through refreshment with a thin layer application. Cold Plastic
emerges as a particularly attractive material option as it considerably reduces VOC emissions in comparison to
solvent-borne paints, thus reducing photochemical ozone creation at the ground level.
LCA studies on road markings should always consider the whole life cycle, since the service life of the products
on the road are decisive for the environmental impacts. The comparison of different technologies must consider
typical application scenarios and should be reviewed by a panel of experts to ensure the credibility of results and
fairness towards all products and solutions.
References
EU Action on climate (2015). Available from: http://ec.europa.eu/clima/policies/brief/eu/. Accessed on 24.06.2015.
Green Public Procurement (2015): Available from: http://ec.europa.eu/environment/gpp/index_en.htm. Accessed on 20.06.2015I.
Greenhouse Gas Equivalencies Calculator. Available from: www.epa.gov/cleanenergy/energy-resources/calculator. Accessed on 04.03.2015.
Ökopol GmbH, IER Universität Stuttgart. 2011 “European directive limiting the VOC content in certain product – Report on potential extensions
of the directive covering road markings”. Review of Directive 2004/42/EC.
