This is an analysis of numerous VicRoads approved light poles and a look into which light pole is the safest for Australian roads. The safest pole is considered that which minimises the risk to both motorists and bystanders from a vehicle collision with a light pole. This document will look at tests performed on different types of light poles and whether they pass or fail the guidelines. We believe these guidelines to be incredibly important, for if the wrong pole is chosen, lives are at stake.
Death and Injury Rate
According to the Bureau of Infrastructure and Transport Research Economics (BITRE) the following are the most recent statistics for Australian roads:
- 1,142 annual road deaths
- 39,404 people admitted to hospital with road crash injuries
While these numbers are falling, they are still too high and far too many people are injured or killed on Australian roads.
Introduction
There are two types of frangible light poles:
- Slip base light pole, considered suitable for roads with low pedestrian activity.
- Impact absorbing light poles, considered suitable for roads with high pedestrian activity.
According to VicRoads TCS 014-3-2001 and AS/NZS 1158.1.3-1997[GG1] , the pole must:
- Restrain the impacting vehicle, and
- Collapse on the vehicle roof, in order to minimise risk of injuring other members of the road traffic.
Plasgain, being a major supplier of light poles in Australia, offer both types of poles, however we have witnessed a drastic difference in the safety performance when a vehicle collides with each pole.
Slip base light poles have a flange at their base which has numerous benefits:
- during installation, the footing can be installed with the light pole attached later
- due to bolts, the light pole can be changed if required without altering the footing
However, when it comes to safety, we’ve witnessed two distinct drawbacks:
- the pole fails to absorb much impact at all if the bolts don’t shear leading to incredible forces applied to both vehicle and passengers causing severe harm.
- If the bolts do shear, the Slip Base light pole does not trap the out of control car and the light pole breaks free which can lead to secondary, and possibly more severe, accidents with other road users.
Enter Safe Pole™
Plasgain’s Safe Pole™ is the alternative – an impact absorbing light pole, developed in Australia and supplied for over 10 years[GG2] . There are numerous impact absorbing light poles marketed in Australia but none like Safe Pole with its patented slots along each seam and continuing down into the footing. The pole is slotted in order to provide controlled crumpling in the impact area as required in VicRoads TCS 014-3-2001 and AS/NZS 1158.1.3-1997[GG3] . The pole remains connected to the footing even at top speeds meaning an out-of-control car will be trapped.
Key Points:
The Safe Pole does NOT have a flange positioned 75mm above ground level as per VicRoads TCS 014-3-2001 requirements. “The removal of this flange is critical for the performance of the light pole in impact.” G. Zivkovic – Automotive Safety Engineering who performed the crash testing on this pole.
TEST 1: 11.0m Safepole collided at 60km/h
Automotive Safety Engineering performed the crash testing which involved an 11m with 5m outreach tapered octagonal Safe Pole with impact absorbing feature. It is made from steel and galvanised for protection against corrosion. And has it’s unique seam slotting feature.
Figure 3: Test 1: Plasgain Safe Pole 11.0m IASLP base before the test
Figure 4: Test 1: Plasgain Safe Pole 11.0m IASLP after 60km/h impact
Figure 5: Test 1: Plasgain Safe Pole 11.0m IASLP after 60km/h impact, front view. Note the pole landed on the roof and bounced off to land beside the vehicle.
The pole crushed along its seams and curled back upon itself and landed on the car roof before bouncing off and landing beside the car. The test received a passing result on the two main criteria: the pole must restrain the impacting vehicle and collapse on the vehicle roof in order to minimise risk of injuring other members of the road traffic.
Result of Test 1: PASS
The total plastic (permanent deformation) of the pole was 1550mm and 320mm for the vehicle front end = 1870mm total deformation.
The impact speed of the vehicle was 62.6km/h and the average deceleration:
- 4.06 “g” over 114ms
- 4.15 ”g” over 50ms
- 4.91 “g” over 10ms
TEST 2: 11.0m Safepole collided at 110km/h
Automotive Safety Engineering also performed this crash testing which involved an 11m with 5m outreach tapered octagonal Safe Pole with impact absorbing feature. It is made from steel and galvanised for protection against corrosion. And has its unique seam slotting feature.
Figure 6: Test 2: Plasgain Safe Pole 11.0m IASLP after 110km/h impact
Figure 7: Test 2: Plasgain Safe Pole 11.0m IASLP after 110km/h impact, front view.
At 110km/h the pole still crushed along its seams, curled back upon itself and landed on the car roof with much more force than at 60km/h. The test received a passing result on the two main criteria: the pole must restrain the impacting vehicle and collapse on the vehicle roof in order to minimise the risk of injuring other members of the road traffic.
Result of Test 2: PASS
The total plastic (permanent deformation) of the pole was 3645mm and 478mm for the vehicle front end = 4123mm total deformation.
The impact speed of the vehicle was 110.7km/h and the average deceleration:
- 6.82 “g” over 124ms
- 10.43 “g” over 50ms
- 14.29 “g” over 10ms
Note: the maximum intrusion of roof panel inside the vehicle occupants area was 257mm at the front and 361mm at the rear of the vehicle. The kinematics of the vehicle occupants are such, that while the falling light pole is deforming the roof downwards, the vehicle occupants’ heads and upper torsos would be moving forward and down, increasing the roof head clearance. The rebound head and torso impact is significantly less severe than the frontal impact as the majority of kinetic energy would already be absorbed in the forward motion.
Secondly, the very drastic trend toward SUV vehicles in recent times would further reduce the probability of serious injury due to increased head room in such vehicles.
TEST 3: 12.0m Safepole collided at 60km/h with ‘slip base’ connection
This test was similarly performed by Automotive Safety Engineering and utilised the same pole as in the previous two tests, albeit 1m longer however differed in that it included the flange positioned 75mm above ground level as per VicRoads TCS 014-3-2001 requirements to be considered a ‘Slip Base Pole’.
Figure 8: Test 3: Plasgain Safe Pole 12.0m IASLP
Figure 9: Test 3: Plasgain Safe Pole 12.0m IASLP at 60km/h
In this test the pole was too rigid such that at 60km/h the pole it did not crumple as required in VicRoads TCS 014-3-2001. The pole passed the first hurdle that it restrained the impacting vehicle, however, it did not collapse on the vehicle roof in order to minimise the risk of injuring other members of the road traffic. The only difference between test 3 and test 1 was the flange. Therefore, received a failing result.
Result of Test 3: FAIL
Maximum recorded deceleration was 48.9 “g” at impact speed of 61.3km/h which is notable that it is 3 times as high as Test 1. Resulting in a much higher force to the passengers of the vehicle to achieve the same result of restraining the impacting vehicle.
It is expected that collision at higher speeds would shear the bolts connecting the pole to it’s slip base leading to the pole failing the first criteria that it would come free and not restrain the out-of-control vehicle, which can lead to secondary, and possibly more severe, accidents with other road users.
Conclusion
The results of the three tests performed highlight the superior performance of the Safepole™ over conventional poles with a flange slipbase system.
At Plasgain, we serve our customers and provide the goods they request and so supply both types of light pole as both are requested. However we believe it pertinent for us to share with the industry the findings of our testing and desire for Safepole impact absorbing light poles to be utilised in all situations.
The initial photos of this report highlight the costs, not only to property and assets but to life when a poor choice of pole has been made. We believe it our duty to educate the market on what are the safest developments in such critical infrastructure.
We implore anyone writing specifications or choosing light poles to please choose the safest pole, choose Safe Pole™.