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Low Deflection Concrete Barriers

Jaybro’s DB80 Deltabloc MASH Approved concrete barrier offers low deflection for maximum safety. It is currently one of the few barriers on the market to already be tested and approved to Austroads’ new 2019 MASH standards.

How do concrete barriers deflect impact?

Concrete jersey barriers are frequently used across Australia’s roads to prevent vehicles from crossing the midline or leaving the roadway.

They do this by absorbing the impact of out of control vehicles and safely redirecting them along the length of the barrier in order to cause the least possible damage.

Choosing a low deflection concrete barrier

The impact performance and subsequent deflection of temporary concrete barriers is influenced by a number of variables. These include the shape or profile of the barrier, its height, and the length of each module. The tensile strength and movement capacity of joints, as well as friction between the barrier and the roadway surface, are also contributing factors.

Correct installation of a MASH approved concrete barrier is important. Many state road authorities specify that concrete barriers must be installed in a minimum ‘run’ or length, and anchored at each end. However, they must not have any intermediate attachment to the road. This allows for the energy of an impact to be released throughout the length of barriers, often causing them to shift slightly in a wave-like pattern as they absorb the shock of impact.

You can see this in action in this video.

The design of the joint connection plays a particularly critical role in the impact performance of the barrier. The design of this joint has a direct influence on the amount of lateral barrier deflection and degree of barrier rotation during impact.

Therefore, a concrete barrier that has a joint with inadequate strength or rigidity can cause the vehicle to become unstable. This ultimately can contribute to the failure of the connection itself, and produce greater than desired deflection.

In the worst case scenario, it can provoke penetration of the vehicle through the barrier.

So – an effective concrete barrier needs to be

  • a specific size and shape
  • be installed in such a way that it dissipates energy on impact
  • be installed in a minimum length so that it can offer effective crash containment
  • be fixed to its neighbouring barrier modules with specialist connection joints
  • plus, it must be tested in accordance with the Manual for Assessing Safety Hardware (MASH) and approved by Austroads.


Ensuring low deflection with the Deltabloc DB80 MASH approved concrete barrier

The Deltabloc DB80 is an F-shape steel reinforced MASH approved concrete barrier, comprising 2, 4 or 6-metre unit lengths with a K150 tension bar coupling system and joint rotation limiting wedges.

With the patented Deltabloc coupling system, the DB80 allows a slight tilting of the impact energy in case of a heavy impact.

The patented coupling and tension bar system is hot dip galvanized and the butt joint inserts minimise displacement.

Elastomer bearings between the single barriers ensure controlled damping of peak loads. This guarantees reliable breakthrough prevention for heavy vehicles and soft impact behaviour for small cars.


  • Suitable for temporary and permanent use
  • No concrete foundation needed
  • No fixation to the ground
  • Fast installation

Dynamic Deflection values

Test vehicle: 2270kg pickup truck

Angle of Impact

10° 15° 20°


Design Speed (km/h)

Deflection (m)

60 km / hr

0.02 0.08 0.17 0.29


70 km / hr

0.03 0.11 0.24 0.42


80 km / hr

0.04 0.15 0.33 0.57


90 km / hr

0.05 0.19 0.43 0.75


100 km / hr

0.06 0.24 0.54 0.95


Working Widths

Test vehicle: 2270kg pickup truck

Angle of Impact

10° 15° 20°


Design Speed (km/h)

Working Width (m)

60 km / hr

0.59 0.63 0.70 0.80 0.94

70 km / hr

0.60 0.66 0.77 0.93 1.13

80 km / hr

0.61 0.70 0.86 1.08 1.36

90 km / hr

0.62 0.74 0.96 1.26 1.63

100 km / hr

0.63 0.79 1.07 1.49 1.94

Expert Assistance with DB80 Specifications

Our specialist team of concrete and safety barrier experts can provide all the documentation you require including test reports and approvals for DB80 MASH approved concrete barriers.

If you are looking to hire precast concrete jersey barriers like the Deltabloc, it can often be more economical to buy, depending on the length of your project. Get in touch with our concrete barrier expert Ben Lorne today for more information and to see where the tipping point is where it becomes more expensive to hire concrete barriers.

Ben Lorne, Barrier Solutions Manager   |   ben.lorne@fortressfencing.com.au

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