EUROPEAN PAVING ASSOCIATION PAVE Concrete safety barriers: a safe and sustainable choice

EUROPEAN CONCRETE PAVING ASSOCIATION

Photo: Gomaco CONTENTS 1. INTRODUCTION

1. Introduction 3 One of the top ten goals set by the White Paper on Transport (2011) is to reduce fatalities in transport. The increase of the safety of the road infrastructure had been one of the seven 2. Benefits of concrete safety barriers 4 main aims of the policy orientations made by the European Commission (EC) regarding to road 3. History of concrete safety barriers in Europe 5 safety for 2011-2020.

4. The European standards: EN 1317 8 From 2010 to 2016, the number of road fatalities in the EU decreased from 31.500 – the equiva- lent of a medium town- to 25.500. This represents a 19% reduction over the last six years. 5. Performance and test methods for vehicle restraint systems 9 However, despite of the fact that the EU has the safest in the world, 70 people are still 6. Terminals, transitions and removable barrier sections 15 dying and 370 got serious injuries every day. These figures are insufficient if the EU wants to 7. CE marking of concrete safety barriers 16 meet its target of halving road fatalities between 2010 and 2020 (only 40 people by 2020). The European Commission also settled as a long-term goal to move close to zero road fatalities 8. Protection of motorcyclists 17 by 2050.

9. Road restraint systems and noise barriers 19 Car occupants account for the largest share of victims (46%). Motorcyclists, who are less 10. Sustainability of concrete safety barriers 20 protected during a crash, account for 14% of road fatalities. Put together, vulnerable road users, including pedestrians, cyclists and motorcyclists account for the same proportion and are 11. Design and construction 25 particularly exposed in urban areas.

12. Conclusions 29 One of the ways to achieve this goal, amongst others such as intelligent vehicles and better enforcement, is safer road infrastructure. The use of passive safety systems and, more 13. References 30 specifically, road restraint systems undoubtedly contributes to higher safety. There will also be more focus on vulnerable road users, motorcyclists in particular. [Ref. 8]

Photo: M. Van Kerckhoven

Photo: Deltabloc

Concrete safety barriers: a safe and sustainable choice 3 2. BENEFITS OF CONCRETE SAFETY BARRIERS 3. HISTORY OF CONCRETE SAFETY BARRIERS IN EUROPE

Another concern of the EC is the use of sus- below lists the benefits of concrete safety Since the 1970s, the central reserves of high- Figure 1 Versions of the old tainable solutions, fitting in the concept of barriers in the three domains of sustainable ways and motorways in Europe have been New Green Public Procurement. Concrete safety construction: environment, economy and protected with (steel) guardrail structures. barriers give answers to both the issues of society. These statements will further be The necessary maintenance on the road road safety and sustainability. The figure discussed in this publication. due to damages from accidents led to con- gestion, especially at narrow road sections. This raised the question of how to develop other types of roadside safety structures. > ENVIRONMENT > SOCIETY

NEW JERSEY PROFILE • 80% less embodied CO2 • Increasing safety for road user than steel systems and worker The need for durable construction with mini- One-sided version that was used in wider central • Minimum material usage • No break-through of mal maintenance and without unacceptable reserves and roadsides and waste collision vehicle reduction in safety soon arose. The concrete • Non polluting in service • Low maintenance increases safety barrier with what is known as a New • 100% recyclable road availability and reduces Jersey profile fitted these requirements. • Virtually maintenance-free over congestion This type of barrier was originally designed their 50-year design life • Safe solution for motorcyclists in America by General Motors in 1955 and • Reduce traffic congestion and first used in New Jersey. The first applica- associated emissions tions in Europe were found in Belgium and France from the 1970s onwards. [Ref. 4]

The New Jersey profile in Europe was more or less standardised in two versions:

bearable Double-sided version, for (very narrow) central reserves ENVIRONMENT SOCIETY planet people CONCRETE STEP BARRIER (CSB) SUSTAINABLE Rijkswaterstaat, the Dutch Road Administra- viable euitable tion, explored other barrier profiles. In the 1990s they developed in the Netherlands the “embedded step” profile, based upon the English “single-slope” barrier. [Ref. 4] ECONOMY prosperity New Jersey barrier in the central reserve of a motorway

Photo: W. Kramer

> ECONOMIC FACTORS

• Very long design life • Minimum space required • Almost maintenance-free • Remain functional even after severe collisions • High daily production of 400 to 800 m possible • Temporary systems available for road works

4 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 5 One of the first applications IN SITU CAST AND PRECAST Surface mounted CSB of the concrete step barrier CONCRETE SAFETYBARRIER installation on motorway E429 in Belgium (1999) Photo: BAM Wegen A concrete barrier can either be cast in situ Photo: P. Van Audenhove or be precast in a production unit.

The in situ installation is done by means of a slipform paver using ready mixed concrete. This kind of installation allows very high daily production rates and consequently com- petitive prices. The barrier can be tied to the substructure (a cement treated or asphalt base layer) or can be surface mounted with- out any anchoring.

Prefabricated elements are manufactured in an indoor environment and assembled on the worksite, making their installation less dependent on climatic conditions. Since they can easily be displaced, they are very 0,05 often used for protection of the work site DEVELOPMENT OF NEW TYPES OF during road construction. 0,085 IN SITU CAST CONCRETE SAFETY Figure 2 Standard geometry of BARRIERS the concrete step barrier 9,0 gon For a long time, mainly between 2000 and 2010, the step barrier was the most used type of in situ cast concrete safety barrier in Europe. After 2010, following the revised

0,90 0,60 version of the European standards EN1317- Photo: L. Rens 1 and -2, new types have been developed, mostly improved versions of the new jersey Precast barriers in a permanent and a temporary installation 0,05 profile.

Photo: Omnibeton – Deltabloc

9,0 gon 0,25

0,542

Photos: left:Givasa right: Deltabloc International

6 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 7 5. PERFORMANCE AND TEST METHODS FOR VEHICLE 4. THE EUROPEAN STANDARDS: EN 1317 RESTRAINT SYSTEMS

In the beginning of the 1990s, CEN, the standardised rules for different types of PERFORMANCE CLASSES – European Committee for Standardisation, road restraint systems. The initial and revised CONTAINMENT LEVELS set up a Technical Committee on road versions, including amendments, of the equipment (CEN/TC 226) and a working European standards of the EN 1317 series The first version of the European standard The low angle containment levels are in- group (WG 1), dedicated to the drafting of are the following (status February 2018): EN 1317-2 was published in 1998. A revised tended to be used only for temporary safety version was published in 2010. The original barriers. However, temporary safety barri- version defined 10 performance classes. ers can also be tested for higher levels of EN 1317-1:1998 Terminology and general criteria for test methods The higher the performance level, the containment. EN 1317-1:2010 (revision) stronger the construction needs to be in

EN 1317-2:1998 + A1:2006 Performance classes, impact test acceptance criteria and test methods for order to withstand higher impact demands. A successfully tested barrier at a given EN 1317-2:2010 (revision) safety barriers including vehicle parapets Each performance class refers to a number containment level should be considered as of crash tests. A road restraint system, al- having met the containment requirements EN 1317-3:2000 Performance classes, impact test acceptance criteria and test methods for located to a specific class, must be able to of any lower level, except that N1 and N2 EN 1317-3:2010 (revision) crash cushions retain the specified vehicles at determined do not include T3. This is because level T3 Performance classes, impact test acceptance criteria and test methods for speeds and impact angles. Table 1 gives an includes a test with a rigid truck (TB41) while ENV 1317-4:2001 terminals and transitions of safety barriers overview of the different standardised crash for levels N1 and N2 only crash tests with tests. cars are provided. Product requirements and evaluation of conformity for vehicle restraint EN 1317-5:2007 + A2:2012 systems The very high containment levels H4a and CEN/TR 1317-6:2012 Pedestrian restraint systems – Pedestrian parapets H4b should not be regarded as equivalent and no hierarchy is given between them. Motorcycle road restraint systems which reduce the impact severity of The difference in tests TB71 with a rigid truck CEN/TS 1317-8:2012 motorcyclist collisions with safety barriers and TB81 with an articulated truck originates from the use of significantly different types Road restraint systems – Guidelines for computational mechanics of crash CEN/TR 16303-1 to 4:2012 testing against vehicle restraint system of heavy vehicles in different countries.

The following normative documents are in phase of preparation (status February 2018):

Road restraint system — Assessment methods and design guidelines for prCEN/TR xxxx transitions — Complementary element TABLE 1 STANDARDISED CRASH TESTS Road restraint systems - Part 5: Product requirements, test and assessment prEN 1317-5 methods and acceptance criteria Test Type of vehicle Mass Speed Impact (kg) (km/h) angle (o) Road restraint system — Assessment methods and design guidelines for prCEN/TR xxxx TB11 car 900 100 20 transitions and terminal connections TB21 car 1300 80 8

Notes: TB22 car 1300 80 15 • crash cushions and pedestrian restraint TB31 car 1500 80 20 The following containment levels systems will not be dealt with in this TB32 car 1500 110 20 are defined (EN 1317-2:1998): publication; • EN = European standard, approved TB41 rigid truck 10000 70 8 • low angle containment:

• A = Amendment TB42 rigid truck 10000 70 15 containment levels T1,T2 and T3; • ENV = Pre-standard • normal containment: • TS = Technical specification TB51 bus 13000 70 20 containment levels N1 and N2; • TR = Technical report TB61 rigid truck 16000 80 20 • high containment: • pr = project, in state of preparation, containment levels H1,H2 and H3; TB71 rigid truck 30000 65 20 not yet approved • very high containment: TB81 articulated truck 38000 65 20 containment levels H4a and H4b.

8 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 9 Table 2 gives an overview of the different THIV (THEORETICAL HEAD DEFORMATION OF THE containment levels. IMPACT VELOCITY) RESTRAINT SYSTEM

Since the revision of the standards EN 1317, THIV was developed for assessing occupant The deformation of safety barriers during parts 1, 2 and 3, in 2010, new containment impact severity for vehicles involved in road impact tests is characterised by the dy- levels “L” have been added to the classes collisions with road vehicle restraint systems. namic deflection, working width and vehicle of high and very high containment. The per- The occupant is considered to be a freely intrusion. formance of the “L” classes is enhanced in moving object (head) that, as the vehicle

respect to the corresponding H classes by changes its speed during contact with the The dynamic deflection (Dm) shall be the the addition of test TB32 with a 1500-kg car. vehicle restraint system, continues moving maximum lateral dynamic displacement of until it strikes a surface within the interior of any point of the traffic face of the restraint ASI (ACCELERATION SEVERITY INDEX) the vehicle. The magnitude of the velocity of system (see figure 4). the theoretical head impact is considered to The index ASI is intended to give a measure be a measure of the severity of the impact of the severity of the motion for a person of the vehicle to the vehicle restraint system. within a vehicle during an impact with a road

restraint system. It is measured and calcu- IMPACT SEVERITY LEVELS lated as the resultant of the decelerations in Photo: L. Rens different directions of a fixed point of the ve- The evaluation of the impact severity indices hicle, close to the centre of mass. The higher is carried out for cars (for the higher and very Example of a precast barrier the ASI index, the more severe the collision, high containment levels, the considered test with very high containment level in general. is TB11 and in case of the L classes, addition- (H4b) on a viaduct ally test TB32). The severity level is deter-

Photo: Deltabloc mined by the highest value from the tests.

Table 3 gives the subdivision in three impact severity classes A, B and C. For each of TABLE 2 CONTAINMENT LEVELS IN EN 1317-2:2010 these classes, a maximum for the ASI value is specified together with a maximum for the Containment levels Acceptance test THIV value, which is the same for the three classes (33 km/h). Impact severity level A Low angle containment T1 TB 21 affords a greater level of safety for the oc- TB 22 T2 cupant of a car involved in a collision than

T3 TB 41 and TB 21 level B, and level B a greater level than C.

Normal containment N1 TB 31

N2 TB 32 and TB 11 TABLE 3 IMPACT SEVERITY CLASSES IN EN 1317-2:2010 (AFTER REVISION) Higher containment H1 TB 42 and TB 11 TB 42 and TB 32 and TB 11 L1 Impact ASI THIV Impact severity class angle H2 TB 51 and TB 11 (o)

L2 TB 51 and TB 32 and TB 11 A ≤ 1,0 and ≤ 33 km/h 20

H3 TB 61 and TB 11 B ≤ 1,4 and ≤ 33 km/h 8

L3 TB 61 and TB 32 and TB 11 C ≤ 1,9 and ≤ 33 km/h 15 Very high containment H4a TB 71 and TB 11 H4b TB 81 and TB 11

L4a TB 71 and TB 32 and TB 11 L4b TB 81 and TB 32 and TB 11

10 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 11 TABLE 4: CLASSES OF NORMALISED The working width (Wm) is the maximum Dynamic deflection, working width and ve- lateral distance between any part of the WORKING WIDTH LEVELS hicle intrusion are important parameters in barrier on the undeformed traffic side and (EN 1317-2:2010) defining the distance that should be allowed the maximum dynamic position of any part between the barrier and an obstacle such as of the barrier. If the vehicle body deforms Classes Levels of normalised working width lighting posts. around the vehicle restraint system so that W1 WN ≤ 0,6 m

the latter cannot be used for the purpose of Figure 4 Dynamic Deflection (Dm), Working Width (Wm) W2 WN ≤ 0,8 m and Vehicle Intrusion (VI ) - measured values measuring the working width, the maximum m

lateral position of any part of the vehicle shall W3 WN ≤ 1,0 m be taken as an alternative (see figure 4). W4 WN ≤ 1,3 m

W5 WN ≤ 1,7 m The vehicle intrusion (VIm) of a Heavy Goods Vehicle (HGV) is its maximum dynamic lat- W6 WN ≤ 2,1 m eral position from the undeformed traffic W7 W ≤ 2,5 m side of the barrier (see figure 4). It shall be N evaluated from high speed photographic or W8 W ≤ 3,5 m N Dm Dm video recordings.

Wm Wm The dynamic deflection, the working width In specific cases, e.g. when there is limited and the vehicle intrusion allow determina- space between the vehicle restraint system tion of the conditions for installation of each and an obstacle, a class of working width safety barrier and also to define the dis- less than W1 may be specified. tances to be provided in front of obstacles to permit the system to perform satisfactorily.

EN 1317-2:2010 provides formulas to turn the TABLE 5: CLASSES OF NORMALISED measured figures D , W and VI into nor- VEHICLE INTRUSION (EN 1317-2:2010) m m m D m Dm malised values DN, WN and VIN. For WN and VI , classes of different levels are defined in Classes Levels of normalised vehicle intrusion N W W EN 1317-2:2010 (see tables 4 and 5). m m VI1 VIN ≤ 0,6 m

VI2 VIN ≤ 0,8 m

VI3 VIN ≤ 1,0 m

VI4 VIN ≤ 1,3 m

VI5 VIN ≤ 1,7 m

VI6 VIN ≤ 2,1 m

VI7 VIN ≤ 2,5 m

VI8 VIN ≤ 3,5 m

D D In specific cases, a class of vehicle intrusion m m

less than VI1 may be specified. Wm Vim Photo: www.gva.be Vim Wm

Wm

Dm

12 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 13 6. TERMINALS, TRANSITIONS AND REMOVABLE BARRIER SECTIONS

IMPACT TEST ACCEPTANCE CRITERIA Terminals are defined as the beginning ENV 1317-4 covers performance classes and/or end treatment of a safety barrier. and test methods for terminals and transi- The test parameters on which acceptance They are required to have specified impact tions. Several systems have been tested criteria shall be assessed are listed in table 6 performances without introducing additional and approved to conform with ENV 1317-4 as a function of the containment level. hazards for passenger cars. for transitions between different concrete safety barriers (precast-to-precast, in-situ- Problems may also arise in the connection to-in-situ, precast-to-in-situ) or between between two different safety barriers having concrete and steel barriers. TABLE 6: TEST CRITERIA PER CONTAINMENT LEVEL consistent difference in design and/or in stiffness. Transitions are required to provide Currently it is proposed to split the pre- PARAMETERS a smooth and safe change from one barrier standard ENV 1317-4 into two Technical to another. Reports (CEN/TR). Containment Safety barrier Impact severity Vehicle Safety barrier level including parapet and level ASI-THIV deformation including parapet vehicle behavior (VCDI) deformation A removable barrier section is defined as a section of barrier connected to a barrier T1 TB 21 TB 21 TB 21 TB 21 T2 TB 22 TB 22 TB 22 TB 22 at both ends which allows for removal and T3 TB 41 TB 21 TB 21 TB 21 TB 41 TB 21 reinstallation for temporary openings. These are mainly used for emergency reasons or N1 TB 31 TB 31 TB 31 TB 31 maintenance access, and which, in closed N2 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 32 TB 11 position, offer appropriate containment H1 TB 42 TB 11 TB 11 TB 11 TB 42 TB 11 performances. H2 TB 51 TB 11 TB 11 TB 11 TB 51 TB 11 H3 TB 61 TB 11 TB 11 TB 11 TB 61 TB 11

H4a TB 71 TB 11 TB 11 TB 11 TB 71 TB 11 H4b TB 81 TB 11 TB 11 TB 11 TB 81 TB 11 Examples of transitions between different concrete vehicle restraint systems L1 TB 42 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 42 TB 32 TB 11 L2 TB 51 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 51 TB 32 TB 11 Photo: Deltabloc Photo: L. Rens L3 TB 61 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 61 TB 32 TB 11

L4a TB 71 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 71 TB 32 TB 11 L4b TB 81 TB 32 TB 11 TB 32 TB 11a TB 32 TB 11 TB 81 TB 32 TB 11

NOT: VCI is not an acceptance criterion

a : The severity level is determined by the highest value from the tests, all results to be included in the test report

Transition between a concrete PERFORMANCES OF IN SITU CAST CONCRETE SAFETY BARRIERS step barrier and a steel system As already stated, the concrete step barrier was for a long time the standard solution for Photo: Linetech in situ cast concrete vehicle restraint systems in Europe. The original tests, performed in 1995, resulted in the following performances:

Containment level...... H2 Working width...... W2 Impact severity class...... B

In the meantime several variants of this solution have been developed, tested and adopted (free standing instead of restrained, different heights and/or widths etc.), mainly in Germany and the UK. Since 2010, other types of in situ cast concrete safety barriers have been developed, most of them with the characteristics H1 to H3 – W1 to W4 – B, all of them CE-marked.

14 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 15 7. CE MARKING OF CONCRETE SAFETY BARRIERS 8. PROTECTION OF MOTORCYCLISTS

CE marking is a declaration by the manufac- Concrete safety barriers must comply with turer that the product meets all the require- the clauses of annex ZA of EN1317-5 so that ments of the relevant European legislation. the barrier system is installed as tested to the CE marking is designed to remove trade Type Testing (TT) and in accordance with the barriers across the EU, giving companies Manufacturer’s Installation Manual. All bar- easier access into the European market to riers are subject to the Factory Production sell their products without adaptation or Control (FPC) conditions for manufacturing rechecking. From 1st July 2013 onwards CE processes. marking will be mandatory for all permanent safety restraint barrier products throughout Precast barrier systems, amongst which all the EU. types of steel guardrails, attain their CE mark on the barrier elements. This is because pre- EN1317 is the product standard for vehicle cast systems are manufactured in a factory. restraint systems. Part 5 contains annex ZA, The installation of precast barrier is carried the “harmonised” part of the standard which out at a separate location to the place of is the basis for CE certification and marking. manufacture. Therefore it is essential that the elements are assembled according to the as tested product. By contrast in situ concrete safety barriers are manufactured on site and therefore the installed system could carry the CE mark e.g. the Britpave surface mounted CSB. Example of a motorcyclist protection device, installed to an existing steel guardrail Photo: L. Rens

Vehicle restraint systems are primarily de- Germany, Portugal and Spain). Based on the signed to contain and redirect cars, buses Spanish test method, a normative reference

Concrete safety barrier constructed under BBS license audit conditions Photo: BBS Barriers and trucks. That means that they do not test has been discussed, and has become necessarily provide protection to other road part 8 of the EN 1317 series, but under the users, in particular motorcyclists. On the con- form of a European Technical Specification trary, in some cases road equipment can be CEN/TS 1317-8 “Motorcycle road restraint an obstacle itself and pose impact hazards systems which reduce the impact severity of for two-wheelers. This is particularly true for motorcyclist collisions with safety barriers”. wire-rope barriers and for conventional steel In the future, these Technical Specifications barriers fixed to steel posts. On the other (TS) may be transformed into a real European hand, concrete barriers with smooth contin- Standard EN. uous surfaces have seldom been reported as dangerous road equipment for powered In the selected test, only the “sliding” con- two-wheelers. [Ref. 7] figuration is considered. (The German method also provides assessing the risk for In different countries protection devices cross-over accidents.) The impact condi- have been developed in order to protect tions are the impact angle (30°), the speed motorcyclists, having fallen from their ve- (60 and 70 km/h) and the choice of impact hicle and whilst sliding along the ground, point (3 different possibilities). In addition, the from hitting the sharp cutting edges of the dummy that is used for the tests hits the pro- steel profiles. In many European countries, tection device (or the barrier) with the head these devices are already being installed in first, which can be considered as the most dangerous spots, mainly curves with a small dangerous but also a rather unlikely situa- radius. tion. The test consists of measuring forces on the head and neck which are related to At the same time, research has been done severity levels HIC 650 or HIC 1000 (HIC = on methods for testing these devices (in Head Injury Criterion).

16 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 17 9. ROAD RESTRAINT SYSTEMS AND NOISE BARRIERS

Discontinuous system Different standards exist for road restraint Another solution consists of installing ap- systems (series EN 1317) and for noise pro- proved barriers, e.g. the step barrier, in front tection devices (series EN 1793 and 1794). of many sorts of standardised noise protec- Nevertheless, both can be combined in one tion devices. system and be tested and approved for Continuous system each of the functions. 30°

Example of a combined system of vehicle restraint system and noise barrier

Photo: Deltabloc

Figure 5: one of the three impact configurations for the Due to the absence of support posts, con- testing of motorcyclist protection systems crete safety barriers, whether slipformed or precast, have a limited risk of impact injuries to motorcyclists.

Example of a cast in situ concrete step barrier Photo: L. Rens

Example of a concrete step barrier installed in front of a noise barrier

Photo: L. Rens

18 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 19 10. SUSTAINABILITY OF CONCRETE SAFETY BARRIERS [REF. 10]

SUSTAINABLE DEVELOPMENT ENVIRONMENT In 2007, Britpave commissioned engineering central reserve, provides a more economic bureau Ove Arup & Partners Ltd. to under- solution than un-tensioned, corrugated Sustainable development is defined by the The cement and concrete sector is com- take cost comparison studies [Ref. 1-2-3] of beam barriers constructed on a central re- World Commission on Environment and mitted to an on-going, concerted and co- various steel and concrete central reserve serve with socketed lighting columns. Development as “development that meets ordinated effort to reduce its impact on the systems. Assuming typical road layouts, this the needs of the present without compro- environment. Key issues include: work looked at both basic barrier construc- Maintenance and service life cost mising the ability of future generations to tion costs and the influence of different meet their own needs”. • Reductions in polluting and greenhouse central reserve layouts and lighting column With a service life of at least 50 years, com- gases during production; options. In terms of barrier costs alone, this pared with around 20 for steel solutions, The following principles are identified to • Efficient use of resources by way of work confirms that surface mounted con- concrete barriers offer significant compara- assist in its delivery: re-used materials and by-products from crete step barrier (H2, W2) compares favour- tive cost savings in terms of end-of-service other industrial processes, such as water, ably with steel systems, which provide infe- barrier replacement alone. • Living within environmental limits aggregates, fuel or alternative cementi- rior containment (N2) and working width (W3 • Ensuring a strong, healthy and just tious materials; or W4). For equivalent containment levels Virtually maintenance-free, even after se- society • Recycling and reduced reliance on (H2), continuous deformable steel systems vere impacts, further high potential savings • Achieving a sustainable economy quarried material; are considered by Arup to be prohibitively to the tax-payer can be achieved. In addi- • Promoting good governance • Environmental rehabilitation after expensive. tion, the inherently high containment level • Using sound science responsibly industrial activity has ceased; of concrete safety barriers effectively elimi- • Effectively, sustainable development • Development of low-energy, durable Investigating central reserve layouts and nates crossover incidents, which improves involves successful integration across and maintenance-free buildings and lighting provision costs, Arup also reported safety and avoids accident recovery costs the ‘triple bottom line’ of environmental, structures. that a concrete step barrier on a fully hard- as well as insurance claims. Congestion, economic and social issues. ened central reserve is less expensive than resulting from accidents and routine road SUSTAINABLE CONSUMPTION an un-tensioned, corrugated steel beam so- maintenance, costs society a lot of money. SUSTAINABILITY OF CONCRETE AND PRODUCTION lution with equivalent containment (H2), sited By increasing levels of motorist safety on a soft central reserve. Similarly, Britpave and reducing maintenance requirements, Concrete is one of the most versatile and du- Production of concrete barrier surface-mounted wide CSB profile with concrete barriers help to reduce this cost rable construction materials known to man, integral cable troughs and mounted light- considerably. making it the most widely used construction Concrete is specified according to EN 206 ing columns, constructed on fully hardened material in the world. Concrete is also one or EN 13369 (precast). Thanks to the use of of the more sustainable building materials blended cement types or the addition of fly when inherent performance properties are ash or ground granulated blast furnace slag,

taken into account. the embodied CO2 of the barrier can be sig- Traces of tyres on a concrete Photo: GIVASA nificantly reduced. safety barrier, showing its resistance to vehicle impacts

Furthermore, the use of recycled aggre- Photo: L. Rens gates such as recycled concrete aggregate (RCA) is permitted and technically feasible in concrete barriers.

Construction Cost

Independent studies comparing the con- struction costs of various barrier systems confirm that the concrete barrier is an ex- ceptionally competitive product.

In addition, with the cost of land being high and space limited, the maximum number of traffic can be obtained by the low working widths provided by concrete bar- riers. Current steel barrier systems do not offer similar reductions to working width.

20 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 21 whole life performance should always be In-service pollution lower than for all other competing solutions considered, given that it is the in-service with similar containment levels. impacts of buildings and civil engineering Research since 1997 confirms that structures that typically dominate. run-off from rural trunk roads and motor- Ecology ways contains pollutants such as metals, With a maintenance-free service life of at hydrocarbons, salts and nutrients as well Animals travel within and between feeding least 50 years, concrete barriers require as microbial waste. Sources of pollution areas, territories and even countries. Such minimal levels of service-life maintenance are reported to include construction, op- journeys are essential for the everyday activity and related traffic management. As eration and road maintenance operations. survival of individual animals as well as for a result, low levels of road-user disruption Steel safety fences and furniture are the maintenance of viable populations. In and congestion are predicted. As the effec- known to be a significant source of heavy addition to the impact of mortality, there is tiveness of catalytic converters for vehicles metals in run-off, particularly in winter the impact of reduced or prevented wildlife idling or travelling at low speed is dramati- months. dispersal and the associated severance of cally reduced, the net result is an overall wildlife territories and habitats. positive impact on service-life greenhouse Concrete does not contain or leach con- gas emissions. taminants and presents no risk to environ- Whilst there are no known data available to mental pollution when used in highway ap- compare the impacts of roads with or with- Steel barriers have a design life of around plications. This is confirmed to be true even out concrete barriers on wildlife, one can 20 years and require maintenance after ve- when crushed recycled concrete is used in easily imagine that that the installation of a hicle impact, an activity often requiring traf- unbound secondary applications. solid central barrier could serve to increase Example of corrosion of a steel guardrail fic management and closures which wildlife mortality and habitat fragmentation. contribute to congestion. As such, over the Highway maintenance programmes – which It is acknowledged that, by the very nature Photo: W. Kramer 50-year lifecycle of concrete barriers, the are more common for steel systems due of its design, a steel barrier is less likely to comparable amount of work, vehicles and to their deformability on impact and rela- block animal dispersal, compared with the energy required to install and maintain a tively short design life – are also known to solid face of a concrete barrier. However, in steel barrier is likely to be much higher. significantly affect sediment accumulation order to minimise wildlife casualties, animal CLIMATE CHANGE AND ENERGY in drainage systems. This impact is clearly population fragmentation and risk to road NATURAL RESOURCES minimised by concrete barriers as they users from vehicle collisions with wildlife, it

Embodied CO2 require minimal maintenance throughout is not the type of safety barrier used that is Recycling their 50-year design life and are typically important. Rather, it is the provision of effec- Comparisons undertaken using industry- situated on hardened medians. tive and targeted mitigation measures that agreed values for construction materials Concrete barriers can be constructed using holds the key to reducing the environmental indicate that concrete barriers out-perform a wide range of secondary and recycled impact impact of road safety barriers. competing steel solutions in terms of levels materials and, at the end of their design life,

of embodied CO2. Table 2 of Britpave pub- are fully recyclable. While concrete barrier construction typically The innovative design of ‘eco-passages’, lication BP42 [Ref. 10] which compares ma- employs steel strand to limit fragmentation such as culverts, , viaducts and terial impacts only (including material pro- Concrete barriers are 100% recyclable – a under heavy impacts, the concrete barrier across roads, in conjunction duction, manufacture and delivery to site), practice now commonplace – providing can incorporate rebar, which, depending with effective and well maintained wildlife clearly shows that the average embodied good quality secondary aggregates, which on the manufacturer, is often manufactured fencing for larger species, is considered to quantity of CO in a concrete step barrier are useable in a wide range of applications. from 100% recycled scrap using an electric present the greatest opportunities for re- 2 (105 kg/m for the Britpave surface mounted arc furnace process. While steel manufac- ducing the impacts of roads and road safety concrete step barrier) is lower than compet- While steel barrier systems are recycla- ture is generally energy-intensive, it should barriers on wildlife. ing N2 (156 kg/m) and, more applicably, ble, the fact that they are typically hot-dip be recognised that the energy needed to H2 (549 kg/m) steel alternatives over a 50- galvanised to prolong their service life produce one tonne of reinforcing steel is as Rather, it is the provision of effective and year period. Indeed, even average values introduces economic and environmental low as half of that required to produce the targeted mitigation measures that holds for dual, surface mounted concrete step constraints. As galvanised steel is recycled same mass of structural-grade steel. the key to reducing the environmental barrier (247 kg/m) and wide concrete step with other steel scrap, the zinc used for gal- impact of road safety barriers. Such miti- barrier (205 kg/m) solutions out-perform vanising volatilises early in the process and Land uptake gation measures have included a modifi- comparable H2 steel solutions. must be collected for reprocessing. Zinc cation to a permitted weephole design to is a chemical waste subject to pollution Concrete barriers require less land than all allow safe passage of wildlife through the Whole-life environmental impact control legislation and requires appropriate competing barrier solutions. Concrete step concrete barrier. collection, treatment and disposal (or recy- barriers with containment levels N2 and H2 While calculations of embodied CO and cling) processes. have a working widths of W1 (0.6 metres) 2 other greenhouse gases are important, and W2 (0.8 metres) respectively, which is

22 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 23 11. DESIGN AND CONSTRUCTION

CREATING SUSTAINABLE In reality, concrete barriers also help to GENERAL constructed, allowing the elements to COMMUNITIES eliminate injury and deaths associated with form a rigid chain. For systems placed on cross-over accidents, barrier intrusions and Concrete barriers can be applied in dif- main roads, this interconnection is required. Construction worker health and safety deflections, and loss of vehicular control on ferent situations. If a central reserve has The standard length is usually 6 m; the soft verges, all of which are typical of steel no obstacles, a double-sided profile is the mass associated with this length can be Highway authorities and contractors are barrier systems. Requiring almost no main- obvious choice. When there are obstacles handled with an assembly crane. With ele- committed to road worker health and tenance or repair after a collision, concrete in the central reserve, such as lighting poles ments of 6 m, curves with a radius greater safety by reducing exposure to live traffic barriers will also help to avoid motorway or columns of portals, a double single-sided than R = 250 m can be achieved. For smaller and lessening risks when on the network, accidents in coned areas, such as those profile can be chosen as an appropriate so- radii, shorter elements should be applied. as well as improving driver awareness and required for maintenance activities. lution. It is also technically feasible to build The elements are already provided with education. These include an urgent review widened concrete barrier profiles, in which openings at the bottom for drainage / of operations that require road workers to Visual impact lighting poles can be integrated. throughput. The openings are also used for be exposed to live traffic, with a view to re- handling and placement of the elements. ducing risks, and a revision of maintenance Visually, concrete barriers provide a smooth, Drainage priorities to reduce the number of visits and continuous structure that is relatively consist- Note: Suppliers of barrier el- ad-hoc repairs and maintenance to cut the ent in terms of texture and colour. Although When the slope of the pavement runs ements usually have several types / profiles need for road workers to be on the network. colour is likely to change with time, due to towards the barrier, removal of rainwater of barrier systems, suitable for different per- the natural degradation of water-based cur- should be taken into account. Drainage near formance classes and temporary situations. Concrete safety barriers mostly require no ing compounds and weathering, it should the barrier can be achieved with transverse maintenance after impact by a vehicle, with remain consistent. From the motorist’s openings at the foot of the barrier, whether Assembly the resultant avoidance of the repair and as- visual perspective, concrete barriers present or not combined with a drainage system. sociated traffic management activities. a low-level screen that helps to reduce glare The installation of precast concrete barriers is at night from oncoming traffic. PRECAST CONCRETE SAFETY usually executed by the supplier. The princi- Motorist safety BARRIER pal contractor must ensure the right place for From a motorist-safety point of view, the installation and a flat surface, usually asphalt. Concrete barriers provide excellent levels visual impact of concrete barriers has been Precast concrete barrier elements are The barriers are installed directly from the of motorist safety. Ove Arup & Partners Ltd., reported to potentially reduce average traf- factory produced in reinforced concrete. truck. Additionally, for large quantities, a one of the world’s leading consultants, has fic speeds. At the end of the elements, producer- depot in the vicinity of the site is made, from undertaken EN 1317-compliant crash tests patented connection systems are where the barriers are transported to the site. and related computer simulations to inves- Noise impact tigate the potential for injury from collisions with concrete step barriers and alternative In 2005, Britpave commissioned a study to Installation of precast safety barriers. EN 1317 uses ASI values for investigate the impact on roadside noise concrete barriers assessing the impact on vehicle occupants arising from the presence of concrete bar- Photo: L. Rens and the ASI values recorded for concrete riers in the central reserve. Arup Acoustics barriers tend to be higher than those for conducted a field study and theoretical deformable steel barriers. However, the analysis to establish any differences in road- study proves that there is no direct cor- side noise levels, comparing concrete and relation between the measured ASI values steel central reserve barriers. and the level of injury. Details of the study are explained in the part “HIC versus ASI” on The results from the empirical and theoreti- pages 11-12. cal studies show that there is a negligible dif- ference in roadside noise levels comparing concrete and steel central reserve barriers.

24 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 25 Photo: Gomaco In situ concrete safety barriers • Compressive strength class: C28/35 or C30/37 The in-situ cast barrier is built on a base • exposure class: XF4 or XD3 surface of asphalt or lean concrete. (use of an air entrainer) Construction is done with a custom slipform • maximum aggregate size: 22 mm paver with a mould. Production rates of 400 • slump class: S1 (a maximum slump to 600 meters are achievable. Behind the of 30 mm is preferred) machine, the extruded profile of fresh con- • minimum 340 kg of cement/m³ crete should not deform. For this purpose it • maximum water-cement ratio of 0.50 is advisable to apply a low-slump concrete • crushed gravel or limestone aggregates with crushed aggregates, to obtain a stable • use of a mix of coarse and fine sand in mixture. order to obtain a smooth closed surface

The following specifications are recom- mended for the concrete mix in an exte- rior environment where de-icing salts are used (based on the standard for concrete, EN 206):

In situ construction of concrete safety barriers with the use of a slipform paver

Photo: Wirtgen Photo: Gomaco Photo: Deltabloc International Photo: Power Curbers

Photo: Power Curbers

26 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 27 12. CONCLUSIONS

To ensure cracking is controlled, the barrier Concrete safety barriers, both cast in situ and The environmental strong points are inher- is typically sawed every 3 to 4 metres to a precast, have been used as vehicle restraint ent to the use of concrete, which in itself is a depth of 5 cm. This sawing happens 6-24 systems for more than 40 years. Their de- sustainable material with limited embodied hours after the construction of the barrier. sign and construction have been modified energy and carbon footprint considered over Automated saw cutting systems have been and improved in order to comply with the the entire lifecycle and with the possibility of introduced to the industry, which allow for European standards EN 1317. Today, they of- using recycled aggregates. Thanks to the greater accuracy of cutting alignment and fer a solution that meets the requirements of minimum working width, concrete barriers depth, whilst also improving worker safety durability, safety, economy and environment. require less space and only one concrete through remote controlled operation. barrier is needed in the central reservation to Concrete is known for its durability and ro- serve both sides of the road. In addition, they bustness. This is also the case for concrete cause no pollution and are fully recyclable safety barriers which have a service life of at the end of life. As it is a maintenance-free over 50 years, do not deform and mostly system, road availability is increased and even stay intact after severe vehicle colli- traffic congestion reduced. sions, and are resistant to all types of climatic conditions.

In terms of safety, a concrete safety barrier Photo: BBS offers a high containment and thus reduces Finally, concrete safety barriers, pre- the risk of crossover accidents. It is designed cast and cast in situ, exist in a wide to redirect errant vehicles without unaccep- range of complete and tested solu- table risks for both vehicle occupants and tions. All precast systems and in situ other road users and third parties. Thanks cast concrete safety barriers, built to its smooth continuous surface and the according to a proprietary design, absence of posts, the risk of impact injuries carry the CE-mark. In the case of in of motorcyclists is also reduced. situ cast barriers, this includes even the manufacturing, thus the installa- The economic benefits are the relatively tion of the barrier. low initial construction cost, the rapid and Concrete safety barriers are a safe easy installation and the fact that concrete and sustainable choice! barriers hardly need maintenance over their service life.

Photo: Omnibeton – Deltabloc

28 Concrete safety barriers: a safe and sustainable choice Concrete safety barriers: a safe and sustainable choice 29 13. REFERENCES

1. Barrier cost comparison – Study 1 of 3 (ref. BP37). ISBN: 978-0-9556962-2-0, Britpave, 2008.

2. Barrier cost comparison – Study 2 of 3 (ref. BP38). ISBN: 978-0-9556962-3-7, Britpave, 2008.

3. Barrier cost comparison – Study 3 of 3 (ref. BP39). ISBN: 978-0-9556962-4-4, Britpave, 2008.

4. Beton – Goed op weg – De betonnen voertuigkering (Concrete – Well on track – the Concrete Barrier), Cement&BetonCentrum, 2015

5. Britpave CSB – The guarantee of safety and quality, Britpave Barrier Systems, 2012.

6. Concrete barriers and roadside noise, DS/CSB/515, Britpave, November 2006.

7. Hampton C. G. The risk of fatality in motorcycle crashes with roadside barriers, Paper number 07-0474, Virginia Tech, United States.

8. http://ec.europa.eu

9. Moderne betonschutzwände (Modern concrete safety barriers), Gütegemeinschaft Betonschutzwand & Gleitformbau e.V. 2010

10. Sustainability Benefits of Concrete Step Barrier – delivering a safe, reliable future, BP/42, Britpave, 2008.

Photo: Agentschap Wegen en Verkeer, Flanders, Belgium

30 Concrete safety barriers: a safe and sustainable choice Photo: E. Schelstraete – E42 Froyennes February 2018 February

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