Feature

Making Forestry Safer

Logging can be a dangerous occupation, but research into logging work practices has helped reduce deaths and injuries.

Mark Sullman, Richard Parker and Patrick Kirk

People employed in the logging industry are exposed to more work environment hazards than any other occupational group in New Zealand. Contributing to the hazardous nature of logging are the chainsaws and heavy mobile machinery, such as skidders, bulldozers and loaders, used within the industry. These hazards have resulted in the logging industry having one of the highest accident rates in New Zealand.

The Human Factors Group of the Logging Industry Research Organisation (LIRO) manages a nationwide logging Accident Reporting Scheme (ARS) database. Data from the ARS is used to identify areas within the logging industry which have high accident and injury rates. The Human Factors Group then conducts research to find out why these accidents are happening and develops methods for preventing injuries to the workers.

Resisting Cuts

In 1980, 41% of all lost-time accidents were chainsaw cuts to the leg. At this time there was no cut-resistant legwear produced in New Zealand and import restrictions prevented suitable garments being brought into the country. Therefore, LIRO, in conjunction with the logging industry and equipment manufacturers, set out to develop suitable garments.

By 1982, the first locally made garments were on the market and cut-resistant legwear became readily available the following year. At this time, chainsaw injuries to the leg accounted for 29% of the total number of reported accidents. This prompted LIRO to recommend the use of cut-resistant legwear, and by 1985 the wearing of cut-resistant legwear was compulsory for every chainsaw operator working within the New Zealand logging industry.

Data on the proportion and number of all lost-time accidents that were chainsaw cuts to the leg showed an initial dramatic decline from 1983 where they accounted for 29% of all reported accidents, to 1986 where this figure was only 8%. The principal cause of this substantial reduction in chainsaw injuries to the leg is thought to be the use of cut-resistant legwear.

Be Seen!

Analysis of ARS data indicated that another area in need of attention was that of worker conspicuousness within the forest environment. "Not seen" accidents, where the worker was not seen and subsequently run over by a machine or hit by a tree, were primarily of concern not because of the frequency of their occurrence, but because of the severity of the resulting injuries. For example, in 1991 there were ten "not seen" accidents reported to the ARS. These consisted of two people killed and eight lost-time accidents (the injured worker could not attend work the following day due to the severity of the injury). The eight lost-time accidents had an average of almost 32 days off work as a result of the injury.

Logging workers traditionally wear dark clothing, since the harsh nature of most logging tasks quickly discolours lighter coloured clothing. This can make it hard for co-workers to distinguish each other from the forest background, which consists of many light-dark contrasts. With the help of Waikato University's Psychology Department, a trial was set up to determine which colour(s) would increase work's visibility and consequently reduce the number of "not seen" accidents.

Ten subjects volunteered to perform ten trials each on a demanding central tracking task (designed to simulate operating logging machinery) while peripherally searching colour slides (designed to simulate scanning the area to locate co-workers) for various coloured test shirts displayed on a forest background. A head-mounted eye-tracker was used to track subjects' eye movements to show which test shirts were detected and in what order.

The results showed that fluorescent yellow, fluorescent orange and white were the most easily seen colours, with fluorescent yellow being the most highly visible against the pine forest background. This research led to LIRO recommending that all forest workers wear fluorescent yellow high visibility garments and helmets. By 1993, most of the New Zealand forest owners required high visibility safety helmets and upper body garments be worn by all people working in, or visiting, their forests. This research also proved beneficial to the roading workers, who also now wear fluorescent yellow garments.

After the adoption of high visibility equipment, the percentage of "not seen" accidents was dramatically reduced to the point where none were reported for 1995. As this dramatic reduction occurred straight after the introduction of high visibility equipment, it would appear that the use of high visibility equipment was the main cause of this reduction.

Wear the Seatbelt

Data obtained from the ARS showed that from 1985 to 1994 there were 77 reported machine rollovers in New Zealand, with 12 (16%) of these resulting in the operators suffering fatal injuries. There has been a steady increase in the number of reported machine rollovers, while the number of fatalities has remained relatively stable, apart from 1994 where five machine operators were killed. The steady increase in the number of reported machine rollovers could be due to a number of reasons including an increase in timber harvested, the steepness of the land harvested, the level of accident reporting and the number of machines working in the industry. Whatever the reason, the trend highlights the increasing importance of improving the safety of machine operation.

The operators of ground-based extraction machinery operate the machinery from within a Roll Over Protective Structure (ROPS). The purpose of the ROPS is to protect the operator from being crushed in the advent of a machine rollover. As the majority of ground-based extraction machines do not have doors, the use of a seatbelt is the most practical method of protecting the operator. Therefore, the use of a seatbelt is one method by which the number of serious injuries and fatalities can be reduced.

Historically the level of seatbelt usage has been low. This low level of usage has continued despite the fact that in 1992 the Department of Labour (Occupational Health and Safety division) made the use of a seatbelt in ground-based extraction machinery a legal requirement. LIRO initiated a study which aimed to determine the reasons for the low level of seatbelt usage in order to rectify the situation. A preliminary survey of the operators of ground-based extraction machinery, in particular those operating skidders, revealed that there were two main reasons for not wearing the provided seatbelts. These were that the operators simply forgot, and that they found the standard seatbelt design inconvenient to use. Part of the inconvenience comes from the fact that in an ordinary day the operator gets in and out of the skidder at least 80 times. Ease of use is thus extremely important to the operators.

The seatbelt was redesigned to make it easier and more convenient to use, and an orange flashing reminder light was installed on the dashboard of the skidder. The light flashed whenever the seatbelt was not fastened and the machine's ignition was on.

Seatbelt usage data was obtained by mounting magnetic reed switches on the outside cover of the seatbelts. The reed switch consists of an open circuit on one side and a magnet on the other. When the magnet and the open circuit were placed in close proximity (i.e. the seatbelt was done up) the magnetic field completed the circuit. The circuit was connected to a relay and a Husky Hunter field computer. When the seatbelt was in use, power from the skidder flowed through the circuit and this was recorded by the on-board computer. This equipment enabled seatbelt usage to be measured both before and after the new seatbelt design and reminder light were introduced.

Skidder operator seatbelt usage was increased by 36% with the introduction of the improved seatbelt design and a further 22% was gained with the introduction of the reminder light. This research has since proved beneficial for New Zealand's forest industry, in that one of the country's largest suppliers of logging equipment has begun fitting a similarly designed and user-friendly seatbelt to all their ground-based extraction machinery.

An industry-focussed research organisation obviously can play an invaluable role in injury prevention and this has been achieved in the New Zealand logging industry.

Patrick Kirk is with the Logging Industry Research Organisation in Rotorua.
Richard Parker is with the Logging Industry Research Organisation in Rotorua.
Mark Sullman is with the Logging Industry Research Organisation in Rotorua.