Last Updated: 10/09/2019
The purpose of this safety alert is to highlight the risk of winch type (wind up) sign failure and risk control measures to help avoid further incidents. This alert applies to winch type signs supplied by SpaceAge Signs and supersedes the alert released in 2014. The principles in this alert may apply to other brands of winch type signs.
There have been two incidents in 2019 at schools in Queensland. In the first incident in May, the winch was attached directly to the support post. The sign was being winched down when it suddenly dropped with the winch wire rope running off the winch drum. The user was able to partially move out of the way but suffered hand lacerations from the falling sign.
The second incident in June involved a sign that had been upgraded with a revised braking system and an offset winch handle. It is understood that the sign was at full height and dropped suddenly with no warning and with no one operating the sign. However, an eight-year-old child was standing near the sign. The sign dropped rapidly and stopped with such force that the rivets holding the sign to its frame were sheared off.
Both incidents had the potential for serious or fatal injuries as the upper part of the signs can weigh in excess of 70 kilograms.
In addition to these latest two incidents there have been a number of incidents in Queensland where wind up signs have dropped. Two of these incidents resulted in serious head injuries.
In the two 2019 incidents the winch wire rope did not break and the safety gear, that is intended to arrest the falling sign, did not operate. It appears that in both incidents the sign dropped due to the clutch slipping (the winch mechanism includes an enclosed clutch assembly). The safety gear failed to operate, possibly because the wire rope remained intact and some tension remained on the rope.
In previous incidents the older type safety gear failed to operate when the wire rope has broken.
Prior to the latest two incidents it was understood that retrofitting the signs with an upgraded version of safety gear would arrest the sign's fall in all situations. However, clutch failure can also cause the signs to drop.
Photograph 1: Sign with an offset winch and upgraded safety gear (similar to the unit involved in the June 2019 incident).
Photograph 2: Older type unit (not upgraded) with the winch attached directly to the post (Note: sign removed from cross bar).
In view of the number of incidents, it is strongly advised that winch type signs are lowered and removed from service unless:
- The signs are upgraded and fitted with an offset handle (i.e. as shown in Photograph 1).
- Engineering design certification has been carried out for the winch and safety gear.
- A competent person:
- carries out a safety inspection on the sign
- provides a signed statement that the sign is safe to operate
- states when a re-inspection of the sign is required.
- On signs with the winch attached directly to the post, the raised sign should be carefully lowered with the operator's body away from the potential fall zone of the sign.
- While an offset winch means that the person raising and lowering a sign is out of the potential fall zone - signs can drop without warning and there is a risk to bystanders.
- Warning labels that indicate people are not to stand under signs may be ineffective for children who ignore the warnings or may not understand that a sign may drop.
- In the case of school children and members of the public exclusion zones can only be relied on when people are physically prevented from entering a high-risk area.
- The winching and braking mechanism on winch type signs is relatively complex and only highly skilled and trained personnel should carry out the safety inspection. Basic ongoing inspection and maintenance can be carried out by others so long as the manufacturer's written instructions are followed.
- While a competent person could potentially carry out a quantifiable slip test on the clutch assembly and then certify the sign, the safer alternative is for signs to be modified so that the raised sign does not rely on clutch friction but on a positive locking device (e.g. a pin or pawl that can be seen physically engaged).
- Any sign upgrades should preferably be in accordance with the instructions of the sign supplier. Irrespective of whether the sign is modified by the sign supplier or another competent person, the design modification should be certified by a Registered Professional Engineer of Queensland. Certification only applies to the actual design. If the upgrade to the sign complies with the engineer's instructions, there is no need for an engineer to inspect and certify every upgraded sign.
- People operating signs are to be familiar with all the safe operating requirements and hazards associated with the sign.
- Do not allow children or students to raise or lower the signs.
- Do not use power tools to raise and lower the signs - as the winching mechanism will be damaged.
- Managing the risks of plant Code of Practice 2013 (PDF, 1.04 MB)