R egardless of what industry you are involved in, safety in the workplace is the number one

priority. Safety can be achieved through the application of legislative require-ments, education, correct working practices, personal responsibility, personal awareness, and any associated and subsequent use of safety related product and tools. However, even after

applying such criteria, there are still too many accidents occurring when working with or near mobile machinery in the workplace.

Recent statistics released from the UK Health and Safety Executive (2011/2012) show that there is a general reduction in the reported injuries and fatalities compared to previously recorded peri-ods and whilst there is a general trend

of declining injuries and fatalities across a range of industries , there are fears that this is bottoming out and in some industries may be on the increase (waste and recycling have seen an alarming increase in fatalities and injuries over the 2012 period compared to previous years and as an example (2011/2012) 29% of fatalities involve being struck by a moving vehicle).

By NIGEL ADAMS

Creating a Safer Workplace with Proximity Warning

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Figure 1: Proximity Warning System

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The Health and Safety Executive Statistics for 2011/2012 report:

◾ There were 173 workers fatally injured in 2011/12 (provisional), equivalent to a rate of fatal injury of 0.6 per 100 000 workers. ◾ With the inclusion of the 2011/12 data into the time series, the trend for the latest four years appears to show a levelling-off in the previous downward trend. ◾ The rate for 2011/12 compares to a rate of 0.7 when an average of the previous five years is examined. ◾ Of the main industrial sectors, construction, agriculture, and waste and recycling have the highest rates. These sectors accounted for 49, 33, and five fatal injuries to workers, respectively.

Whilst not all vehicle incidents could have been avoided/ risk reduced with the adoption of technology there are very well documented cases of recent incidents involving vehicle impact due to personnel being on the ground where the application of technology may have removed the need for them to be so close to the site of the incidents or at least have the option of warning the vehicle operators of the presence of personnel.

As a general rule site worker/pedes-trian safety can be achieved by:

1. Good working practices—this includes training and education, well managed sites, implementation of pedestrian segregation from moving plant, correct procedures and corrective actions for trans-gressions from any local / national rules that impinge on safety.

2. Additional aids / tools, fitted as standard to machines—mirrors, reversing cameras, reversing/forward looking radar

3. Personnel/pedestrian detection

In many cases, applying (1) is sufficient, however this may not always be possible especially in cases where it is essential to have ground workers on site, exposing them to the risks of moving plant and vehicles.

A range of technology is available to detect personnel and this includes optical (mirrors, cameras etc), radar, ultrasonic, RF (Radio Frequency). They each have their benefits, but I will focus on RF as this is a technology which specifically targets the pedestrian and reduces the possibility of false alarms. This type of RF warning system is becoming commonly known as PWS (Proximity Warning System) and uses two main components—a field genera-tor/detector and a transponder. The field generator (antenna) is mounted on the vehicle and produces the detection zone. The transponder is worn by the pedestrian. When the transponder enters the zone produced by the field generator the alarm conditions can be detected, generated and actioned.

RF proximity detection systems are very effective. By installing an active system such as this (vehicle sensor units and RF tags on personnel) then an effec-tive warning system can be created giv-ing indication that person(s) are within a predefined warning zone (see Figure 1). This does not give precise location of the personnel (yet), but can warn the machine driver both audibly and visually of their presence, and in some cases can be wired into the machine to cease motion or similar action. This is

Figure 2: SiteZone PWS Base Station on the counterweight of an excavator

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more effective than reliance on passive systems as the warning occurs without the need for any positive action from the machine operator/driver.

One commercially available system known as SiteZone has been enthusiastically received in the UK and has entered service in a wide range of industries including: construction, civil engineering, waste and recycling, warehouse and distribution.

Site Zone surrounds a vehicle with an invisible 360° detection zone. When this zone is breached by personnel wearing a Site Zone transponder the driver is alerted to the risk via an in cab audible and visual alarm, there is also an optional warning for pedestrians. One of the main benefits of Site Zone is that it is not dependent on line of site and can detect transponders around blind corners and other obstacles.

Site Zone has been designed to be robust and flexible enough to meet the needs of the construction industry and can be deployed on almost any type of plant from forklift trucks and mini excavators through to wheeled loader, large excavators, bulldozers and even larger plant such as ADTs. Detection zones are customisable by strategic placement of the zone generator (known as the PWS Base Station—see Figure 2) and the system has an adjustable range of up to 10 metres.

Site Zone can affect behavioural change which is in part due to its data logging feature. Each breach is recorded in the system memory which can be downloaded and used to identify indi-vidual training needs or areas requiring operational improvement. There is also the option to fit a telemetry module which is ideal for organisations operat-ing large fleets across single or multiple

sites as it allows data to be accessed via a customer dedicated website removing the need to visit individual machines.

The effectiveness of the SiteZone system is best summarised with the following case study:

ClientMcArdle Group

Equipment360° excavators, bulldozers, articulated dump trucks

Equipment Deployment Single & Dual Antenna Site Zone Proximity Warning Systems with telem-etry module, external alarms, dead-man handle integration for excavators, Site Zone tag test station, and long life Site Zone transponders

Background The works package involved the

restoration of a former aggregate recycling yard to natural landscape. The project ran for a period of approximately six months and involved:

◾ Removal of buildings ◾ A contamination remediation strategy ◾ An earthworks package to deliver a landscaped surface including use of in situ site materials ◾ Top soiling and rendering the landscape capable of supporting grass seeding ◾ Landscaping aftercare for a period of 12 months

GeneralAs part of their constant commitment to site safety McArdle Group has been an early adopter of the Site Zone proximity warning system. The system was deployed on all McArdle machines working on this site, this included a

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number of excavators in the 20–30 tonne range, bulldozers and 3 articulated dump trucks. Appropriate detection zones were set around each machine, these were 5m for the excavators and dump trucks and 8 metres for the bulldozers.

Each system was fitted with an external alarm so that pedestrians as well as drivers could be warned when a zone breach had occurred.

Site Zone ManagementDue to the nature of this project a number of contractors were operating on the project at any one time, all of these ground personnel were issued with personal transponders and made aware of the systems operation via the Sites Induction process. This induction

process was also used for transient visitors. In order to maintain full system integrity personal transponders were tested on a daily basis using the transponder test station, this process take a few seconds.

Site ManagementAll Site Zone systems have a data logging facility. Due to the number of machines on this site McArdle stipulated that all data collection should be remote and accessible in real time therefore all systems were fitted with the Site Zone PWS telemetry module. When a zone breach occurred the event was logged locally and transmitted via the telemetry module to a secure website where McArdle could view and

interpret the data. This method allowed McArdle to conduct real time manage-ment of the plant—personnel interface.

ConclusionThe use of the Site Zone system provided an additional tier of protection to the stringent workplace transport safety measures already employed by McArdle. The system gave universal protection and the personnel transponders were used as an extra piece of PPE. Workplace transport management was possible using Site Zone telemetry capability. MC

Nigel Adams is based in the UK, and was formerly the Engineering Director for Prolec Ltd. He now owns OnGrade Ltd and focuses his 25 years experience on machine guidance and safety.

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