Bull bars - Is fitting them a bad idea?

The idea of fitting of a bull bar to a car or SUV tends to divide people into two camps. There are those that loath them as being obnoxious symbols of entitlement and those that see them as a sensible precaution against the dangers of country roads.

Bull bars do have a place but that place is probably not an urban street where it could present a risk to pedestrians or other vulnerable road users. Not only that, a poorly designed bull bar also risks driver and passenger safety by altering the way the car performs in a crash.

On the other hand Australia has a unique road system, in part characterised by large expanses of sparsely populated territory. The many remote roads that join rural communities are populated by wildlife, especially kangaroos who’s road safety mantra is ‘look left, look right and go regardless’. Stray livestock also pose a problem for people driving through these areas. These beasts are large enough to disable a vehicle and even injure occupants if you were unlucky enough to hit one. So to come out and say “thou shalt not fit a bull bar” is not a realistic proposition for many.

What are the benefits and shortcomings of bull bars?

Let’s have a look at some of the engineering and science involved. A bull-bar is a rigid structure, usually metal (plastic bars also exist) which is fixed to the front of a vehicle and is designed to protect a vehicle against damage to items such as the radiator and headlights.

The Australian Design Rules (ADR) are a bunch of design requirements for vehicles that set minimum standards for Safety, Emissions and Anti-Theft equipment. ‘ADR 42—General Safety Requirements’ states that “no vehicle must be equipped with any object or fitting, not technically essential to such vehicle, which protrudes from any part of the vehicle so that it is likely to increase the risk of bodily injury to any person”. Interpretation of this ADR hinges on what is meant by “Technically essential”. It is clear that bull bars certainly increase the risk of bodily injury, that’s how they work. Their whole purpose is to prevent energy being dissipated through the body of the vehicle when it strikes an animal. In order to satisfy Isaac Newton more of the energy of the impact must therefore be taken by the animal’s body which will injure it more. Exactly the same physics applies to pedestrians too.

So most state registration bodies including VicRoads skirt this part of ADR 42/04 and instead refer to compliance to Australian Standard AS 4876.1 2002. The long and the short of this requirement is

  • The bull-bar shall follow the profile of the vehicle to which it is fitted.
  • Fitting the bull-bar must not increase the width of the vehicle (excluding  the mirrors).
  • Any sharp edges on the bull-bar shall be chamfered or radiused.
  • No open-ended frame members are allowed.
  • No small components (such as brackets) shall be attached to the front of the  bull-bar.

But the story doesn’t end there. For the last fifteen years or so vehicles have had to comply with ADR 69 and ADR 73 which requires vehicles to protect occupants in a front-on crash. In modern vehicles, compliance with these ADRs can be dependent on a predictable rate of deformation of the front end structure. Also calibrating airbag deployment is a precise thing and how this is affected by a blooming-great metal edifice attached to the front end is very much dependant on how well it is designed and mounted.

So to maintain compliance with these two ADRs, VicRoads in addition to the Australian Standard Compliance also require (in its own inimitable words) that any bull bar fitted to a vehicle that is subject to ADR 69 and ADR 73 must demonstrate that it;

  • Has been certified by the vehicle manufacturer as suitable for that vehicle; or,
  • Has been demonstrated by the bull bar manufacturer to not adversely affect the vehicle’s compliance with ADR 69 or ADR 73 or interfere with any critical air bag timing mechanism as the case may be.

For their part we reckon bull-bar manufacturers need to put their resources into continuously raising the bar (forgive the pun) and improve their designs to be not only compatible with roadworthiness requirements but also to minimise injuries to unprotected road users.

So should you fit a bull bar or not?

Ultimately it is the motorist who must make the call, for instance here at the RACV our policy is not to fit them to our fleet vehicles, although occasionally our regionally based contractors do. Have a think about your motivation too, is it just to make your car look tough or do you travel in the country enough that roos are a constant hazard? Another thing to consider is that bull bars are essentially dead weight and do not exactly improve aerodynamics either. Therefore expect to use more fuel if one is fitted. Also since a bull bar is part of the gross vehicle mass the added weight of the bar will also directly reduce the maximum payload your vehicle can legally carry, which could be an issue for utes and vans.

If you do decide to fit a bar, you must make sure your car is still roadworthy and since properly functioning airbags are a part of being roadworthy then one that is compatible with your cars crashworthy design is required. It’s also worth noting that gear that’s often stuck on bull bars such as winches, fishing rod holders and vices may actually make the vehicle un-roadworthy, depending on how they are mounted.

Certainly the days of merrily knocking up a bull bar out of bits of scaffolding and angle-iron in your shed are long since gone. These days a lot of design and testing goes into making a good bull bar that complies with the regulations. This has also made them quite costly.

All in all there’s a lot to consider.

To help you out, VicRoads have a Vehicle Standards sheet giving the low-down on do and don’ts when it comes to bull bars.

But maybe technology might eventually make them obsolete?

Written by Nicholas Platt
May 09, 2016