NEWS
23/02/22

Passive sign posts proven to reduce the impact in a road crash

Road collisions are a leading cause of death globally, claiming more than 1.35 million lives each year and causing up to 50 million injuries.

While excessive speed, drink and drug driving, using a mobile phone at the wheel or failing to wear a seatbelt are the most obvious causes of collisions, the severity of a road crash is influenced by a number of risk factors. 

One risk factor responsible for many road deaths and serious injuries every year is fixed roadside objects, such as trees, lighting columns, poles and road signs, causing a major road safety problem worldwide, according to the World Health Organisation (WHO).*  

 

The physics of a collision

When a road crash occurs, the vehicle and its passengers quickly decelerate. 

The speed that the vehicle is travelling at the point of impact, the weight of the vehicle and the weight of the object it collides with determine how much force is exerted on the vehicle.

Modern cars have safety features that absorb kinetic energy in collisions, such as seat belts, air bags and crumple zones, but this is not always enough to prevent death or serious injury to the vehicle occupants.

A light object, which moves easily on impact, will absorb some of the vehicle’s kinetic energy, thereby limiting the severity of the crash.

However, colliding with a heavier stationary object such as a lamp post, which is not crash-protected, could have disastrous consequences for the vehicle and its passengers.

If the force on impact is not sufficient to move the object, it will send a considerable force back to the vehicle.

 

The need for passive posts and masts

WHO’s ‘Road Traffic Injury Prevention: Training Manual’ states that impacts between vehicles leaving the road and solid roadside objects are usually single-vehicle crashes and frequently involve young drivers, excess or inappropriate speed, the use of alcohol or driver fatigue.* 

The document goes on to say that the linkage between vehicle crash protection and roadside crash protection needs to be strengthened. The road environment needs to be designed so as to eliminate head-on collisions – into trees, poles and other rigid objects – at high speeds, where the car itself cannot offer sufficient protection.

In view of these issues, passive traffic sign posts have been developed to minimise the damage caused to a vehicle and its occupants in the event of a crash.   

Tested and approved to BS-EN 12767, they provide a safer alternative to traditional posts and columns.

Made in either aluminium, steel or glass reinforced plastic (GRP), passive support posts have either high-energy, low-energy or non-energy absorbing qualities, which reduce the risk of injury to vehicle passengers in a collision.

 

The HiMast 

Varley and Gulliver’s HiMast passive post is recognised across the industry due to its frangible design and non-energy absorbing qualities.

The anti-climb posts are classified to 50, 70,100:NE:C:S:SE:MD:0 in accordance with BS EN 12767:2019, meaning that a vehicle loses minimal speed on impact with the HiMast at a range of speeds. 

It is available in a wide range of sizes, allowing for installation along any road and provides an alternative to traditional structural steel poles that are protected by safety barriers. 

Made of aluminium, the HiMast is multi-directional and can be impacted from any angle and still provide the same performance.

HiMast is designed to shear or breakaway following a vehicle impact to minimise the harm to the vehicle’s occupants, and as an additional safety barrier is not required, it offers a significant cost saving. 

Stacy Willis, Sales Manager, at Varley and Gulliver, said: “Passive posts and masts play an important role in road casualty reduction by limiting the injuries sustained by a vehicle’s occupants in the event of a crash.

“We are really proud of our range of passive posts, which are strong enough to support large road signs, but are designed to break off safely if a vehicle collides with them even at low speeds, thus reducing the impact for the driver and other passengers.”  

  

Research into passive posts

A report published by the Transport Research Laboratory (TRL) more than 20 years ago on behalf of Transport for London (TfL), recommended the use of BS-EN 12767-approved passively safe signposts and lighting columns. 

The report stated that ‘they are particularly suitable where it would be difficult to use a safety barrier, or where the safety barrier itself could pose a hazard, for example at a nosing or on a roundabout splitter island.’**

It concluded that ‘there appears to be a good economic case for the introduction of passively safe lighting columns, based on a small additional cost per lighting column, due to the reduction in collision severity, particularly in locations where there would otherwise need to be a safety barrier.’

 

Victims of collisions involving roadside objects

RoadPeace, the national charity for road crash victims, provides information and support services to people bereaved or seriously injured in road crashes. The charity also engages in evidence-based policy and campaigning work to fight for justice for victims and reduce road danger.

Nick Simmons, CEO of RoadPeace, said: “There are too many objects at the roadside and we’ve supported far too many families whose loved ones have been killed following collisions with trees, lamp posts and other street furniture.

“Traditional poles and posts can have a serious adverse impact on vehicle passengers in a collision, so RoadPeace strongly supports the use of passive sign posts and masts.”

 

For more information about the HiMast contact stacy@varleys.co.uk

*Risk Factors for Road Traffic Injuries – Road Traffic Injury Prevention: Training Manual – World Health Organisation (WHO) – 

https://www.who.int/publications/i/item/road-traffic-injury-prevention-training-manual

** ‘The Use of Passively Safe Signposts and Lighting Columns’ by GL Williams, JV Kennedy, JA Carroll and R Beesley (TRL) 2008 – https://www.trl.co.uk/publications/ppr342