Posted by Matthew Mac Partlin on Thursday, June 6, 2013 
I've previously taken a (non-engineer's) look at run-offs and gravel traps and their role in minimising harm in motor sport crashes (ASMMR Newsletter Vol 2 Issue 4, May 2010). Having watched the Monaco F1 GP at the weekend and in particular the impacts of Felipe Massa and Pastor Maldonado, I've done a little digging around the type of crash barrier used. The Monaco circuit, which is a street circuit, uses a brand of barrier called TECPRO Barriers. TECPRO barriers are also used at the Melbourne, Barcelona, Silverstone, Monza, Singapore, India and Abu Dhabi circuits. Installation has been started at the South Korean circuit in Mokpo and they will be in place at Austin, Texas in November.

Most of us who have worked at a circuit event will be aware of the array of crash barrier materials currently in use. These include hay bales, water barrels, concrete barriers, Armco barriers (a trade name that has become synonymous with a particular design of barrier; like Kleenex for tissues and Aspirin for acetylsalicylic acid) and tyre walls.

Tyre barriers at Oran Park, NSW (before it became a housing estate). 

Red and white water-filled plastic barrier can be seen in the background.

(Picture from personal library)

An Armco barrier.

A hay bale crash barrier on the Isle of Man TT circuit

A concrete barrier with catch fence at a V8 Supercar event in Canberra, ACT.
(Picture from personal library)

Crash barriers are generally divided up into rigid, semi-rigid and flexible barriers and which one to use is determined by its location and proposed function. Dedicated race circuits are easier to plan for, while street circuits and rallies often have physical and logistical limitations to the placement of crash barriers. While there are regulations guiding the design elements and procedures required for recognition of a race circuit, for example Appendix O of the FIA Regulations, the choice and layout of individual elements are left to the circuit designers.

If you absolutely want to prevent a vehicle from leaving the circuit, use a rigid barrier; though incidences of competitive vehicles flipping over or crashing through rigid barriers are well documented. These barriers are often placed where the harm from a vehicle leaving the circuit outweighs the harm due to impact with the barrier; for example the roadside drop-offs on the Pike's Peak hillclimb route. The vehicle will generally be stopped, but the deceleration forces and resultant injury risk on the competitors inside the vehicle will be significant in the absence of any other deformable structures.

One of the Pike's Peak Hillclimb corners.

Rigid barriers, such as concrete blocks and Armco barriers, work best and cause the least damage to the car's occupants when the direction of impact is roughly parallel to the orientation of the barrier. In this situation the barrier serves to redirect the vehicle back on to the circuit. This strategy is most obvious at events such as NASCAR, where the errant vehicle strays wide but its predominant direction is along the barrier rather than directly into it.

However, there is the risk that an uncontrolled car gets deflected back into the path of other vehicles, precipitating multiple collisions.

An IndyCar collision at the Indianapolis 500

The free ends of a rigid barrier need to be cushioned as well, if they are a potential point of impact, such as at the entrance to the pit lane. This is achieved by the use of stacked hay bales, tyres or water-barrels bunched around the exposed barrier end. Armco barrier ends are usually curved off to prevent them acting as spear tips on impact.

If a head-on impact with a rigid barrier is unavoidable, some form of energy absorbing barrier (semi-rigid or flexible) will usually be placed in front of the rigid structure. Combined with deformable structures on the vehicle (“crumple zones”), this extra layer serves to decelerate the car as much as possible before the rigid barrier is struck. Traditionally this has been achieved with hay bales, water barrels or a tyre wall. Over the past decade, work has been done with plastic and polyethylene containers to try and determine the optimum configuration and structure for a given circuit location.

Energy absorbing barriers are not without their problems, however. They are usually constructed of individual elements that are in some way laced together. When a vehicle strikes the barrier at high speed, while deformation is integral to the function of the barrier, there can be unintended outcomes such as:

  • high-energy container rupture with the potential for shrapnel-type injuries, 
  • submarining or deep embedding of the vehicle, making extrication and competitor access almost impossible, or,
  • the vehicle riding over the barrier and being launched into the air

In addition to the crash protection characteristics of the chosen barriers, there are other features that need to be considered when constructing a crash barrier for a race.
  • Size and weight of the barrier's components
  • Ease of construction
  • Ease of repair, both after and during a race
  • Ongoing maintenance requirements

So there has been a fair amount of research and development over the past decade into crash barrier structures. The products of all of this R&D include the SAFER barrier, used in North America on IndyCar and NASCAR ovals and circuits, and the TECPRO barrier, which started out in karting events and became the favoured option for Formula 1. 

The SAFER barrier was developed at the Midwest Roadside Safety Facility of the University of Nebraska-Lincoln by an engineering team headed by Dr. Dean Sicking ( in an attempt to create a barrier that met the needs of oval racing. Prior to its installation, concrete blocks, Armco barriers and wire-mesh catch fences were the standard, with tyre bundles and water barrels placed at strategic points. There had been problems with cars getting flipped up into the catch fence, sometimes with devastating consequences for competitors and spectators. After 4 years in development, the SAFER barrier was first introduced in 2002 and has since been retro-fitted in front of the concrete walls for almost all IndyCar and NASCAR circuits, as well as being installed on civilian roadways. It is a composite design, consisting of:

  • a set of eight 28 metre square steel pipes arranged horizontally and welded on top of each other to form the impact plate
  • the impact plate is reinforced every 20 meters with a vertical metal strut
  • a stack of shaped polystyrene boards arranged at set intervals behind the impact plate provides the energy absorbing  zone
  • the assembled barrier is then tethered to bolts anchored into the concrete wall along the edge of the track

The SAFER Barrier being tested

The intentions of this design are several:

  • provision of safer crash deceleration
  • prevention of the car being caught and spun or flipped
  • prevention of the car being deflected back on to the path of oncoming traffic
  • suitable for both open and closed wheel race cars
  • ease of construction, maintenance and repair

The SAFER barrier has not been without its problems and recently there was an issue with corrosion of the bolt anchors used to secure the tether to the concrete wall. There has since been a recommendation issued that the original carbon steel bolt anchors be replaced with a galvanized anchor to prevent corrosion.

On the other side of the Atlantic, at about the same time and following Michael Schumacher's tyre wall impact at Silverstone in which he broke his leg in 1999, a 6 year R&D project started. It became a collaborative effort between the FIA, German engineering group DEKRA and French barrier manufacturer TECPRO. The group lead was Hubert Gramling, a German engineer and a major research consultant for the FIA Institute;,who was also involved in refinement of the HANS device and wheel tethers and continues to work on the FIA's open and closed cockpit and karting research groups.

The challenge was to develop a crash barrier that could provide safe deceleration (<8m/s or <60G), was easy to assemble and repair and would not take up too much space (important for limited run-off circuits such as Monza, Singapore and Monaco). Similar to the SAFER barrier, the result was a composite structure, made up of:

  • a series of polyethylene foam-filled polyethylene blocks, reinforced at their centre with a 2mm metal plate (R1)
  • each block is linked to the next with 3 high-tensile nylon straps, providing a flush surface impact barrier wall 
  • a second set of empty, sealed polyethylene blocks interposed at set intervals behind the R1 impact blocks to  provide the energy absorbing  zone (R2)

The R1 and R2 blocks are 1.2m high, 1.5m wide and 60cm deep and the R1 block weighs about 120kgs (Can be carried by 2 people)

TECPRO barrier showing 2 layers of R1 reinforced, interlinked wall blocks (grey) and the interposed R2 absorbant blocks (red).

The blocks can be set up as a single or double layer depending upon the anticipated speed at impact; e.g. <90kph → single layer of R1 and R2 blocks. They can be used on their own, placed in front of a rigid barrier or in front of a traditional tyre wall, depending upon the space available and intended function.

TECPRO barrier configurations
(From the TECPRO Booklet)

Gramling's crash tests, assisted by DEKRA and TECPRO, showed that while tyre walls held together with 20mm conveyer belt ruptured at speeds in excess of 100kph, the TECPRO barrier functioned safely up to 218kph (The true maximum may be higher, but this is the highest speed tested to date).

TECPRO claim additional advantages to their barrier system, including:

  • ease of portability
  • ease of assembly, maintenance and repair
  • the rounded off interlink allows the barrier to be erected around various corner configurations
  • lower cost and time required for installation
  • the blocks are sealed structures and therefore don't collect water or discarded rubbish
  • more rapid degradation than tyres once disposed of

No system provides a 100% safety guarantee, but risk of harm can be significantly reduced by combining the most effective elements in the right context. This includes not just crash barrier configurations, but also circuit design features such as run-off areas, vehicle safety elements such as deformable nose-cones and side pods and competitor equipment like the integration of helmet, HANS device and safety harness arrangement. Further developments are likely to continue as the trade-off is usually that the drivers feel safer and so push harder.

References and resources

The SAFER barrier

The TECPRO barrier