HAVS Risk Management

 

HAVS MANAGER CONTROLLING THE RISK

Chris Simpson, Richard Welbourn, Mel Watson & Karolyn Toner*
Leeds City Council Parks & Countryside & *HAVS Risk Management
The Farmhouse, Redhall Lane, Leeds UK
info@havsrm.com

Abstract

Leeds City Council, Parks & Countryside Service are currently piloting a risk management system as a practical way to implement Directive 2002/44/EC. The software uses a combination of the H.S.E's points system and a traffic light system to calculate and highlight vibration exposure levels. Operational teams representative of the workforce were monitored carrying out various duties. Allowable operator usage times were calculated using the vibration readings provided by the manufacturers. The initial readings were then replaced with on site task specific readings. These new site readings were found to be substantially higher, resulting in a dramatic reduction in allowable operator exposure limits. With the new readings in place the forecasting facility was then able to predict and act as a preventative measure to calculate and eliminate potential future vibration exposure that exceeded statutory limits. Health surveillance was initiated for employees who occasionally breached their daily exposure action values (EAV's). Where exposure limit values (ELV's) were encountered tasks were eliminated or job rotation and additional training ensued.

1. Introduction

The introduction of the European Physical Agents (Vibration) Directive in 2002 lead to the Control of Vibration at Work Regulations 2005 being enforced on the 6th July 2005. The new legislation defines the legal limits for acceptable magnitudes of vibration that workers can be exposed to. It is now the employer's legal duty to determine and assess workers risks of exposure to vibration and where practicable reduce exposure levels. Training must be provided to raise awareness of the risks associated with working with vibrating tools and health surveillance must be implemented where the evaluation of working practices shows a risk of exposure exists. This pilot study focuses on the control and management of hand arm vibration.

2. Method Used for Calculating Vibration Exposure

Prior to the change in legislation there were no enforceable limits for hand arm vibration exposure although there existed case law and compensation claims for vibration white finger. Previous estimates for exposure levels used the dominant axis magnitude calculated to an action value of 2.8m/s2 >A(8). A(8) being the eight-hour energy equivalent acceleration. It is now necessary to consider vibration on a total or "triaxial" basis taking into account the root sum of the squares in each of the three orthogonal x, y & z 22 axes. Hence if ahv=ahx+ a2 hy+ ahz the following calculation can be used to assess vibration Presented at the 40th United Kingdom Conference on Human Response to Vibration, held in Liverpool, England, 13-15 September 2005. exposure levels over an eight hour period A(8) = ahv t/8. (Note: A(8) is the eight-hour energy equivalent acceleration, Ahv is the vibration total value where the root-sum-of-squares of the three axes is used and t is the exposure time of a worker to the vibration from the tool process). Exposures can then be standardised to an exposure action value (EAV) and an exposure limit value (ELV) which are legally defined as 2.5m/s2 A(8) and 5m/s2 A(8) respectively. Where the exposure action value is exceeded health surveillance must be implemented and a risk reduction plan instigated to minimise exposure levels preventing operatives reaching the limit value. The limit value must not be exceeded and where risk assessments show a likely breach of the limit value further investigation should ensue to control exposure and prevent the occurrence. It should be noted that the Directive does allow a weekly (40 hour) average to apply where vibration exposure varies markedly from time to time provided exposure is usually below the exposure action value and does not exceed the weekly averaged limit value. This pattern of exposure must show that the risk is less than that of the corresponding risk from constant exposure at the exposure limit value. When these circumstances do apply the risk must be reduced to as low a level as is reasonably practicable, taking into account any special circumstances and the employee concerned should be subject to increased health surveillance.

Once the vibration magnitude has been established it is easy to calculate and control allowable exposure times with single tool usage. Recognising the calculation becomes more complex with multi-tool use the HSE created a vibration calculator using a points system as a way of expressing different combinations of vibration magnitudes and exposure times instead of using values in m/s2 A(8).

The points are easier to work with and can be added together where workers are exposed to two or more different sources of vibration in a day. In the points system the EAV of 2.5m/s2 A(8) is equal to 100 points and the ELV of 5m/s2 A(8) is equal to 400 points. The software system from HAVS Risk Management used in this pilot study by Leeds City Council combines the points system with a traffic light system to create a software program called the HAVS Manager that monitors and controls workers exposure to hand arm vibration.

As a brief overview of the system, green is used for the threshold level of below 100 points, amber for the EAV of 100 to 399 points and red for the ELV of 400 points and above. Workers vibration exposure is collated through time sheets recording machine type, vibration magnitude and trigger times. Personnel, training and medical histories are stored but only accessible by authorised personnel. Tool inventory includes, manufacturer, model, age, service history, vibration magnitude (test source, date and history). The report generator manipulates data identifying workers who have breached EAV’s or ELV’s, require training or need increased medical screening. Graphical displays pin-point tools with unusually high vibration magnitudes and any department or individual at risk is clearly identified. The forecast facility predicts exposure levels in task specific environments allowing effective risk management to reduce the incidence of Hand Arm Vibration (HAV).

Figure 1. HSE calculator in use.

The illustration shows 3 tools in use over an 8-hour working day. The vibration magnitudes are 2, 6 and 3.5 m/s2 and the total exposure times are 15, 30 and 90 minutes respectively. The results (in the yellow cells) show the partial exposure values for the 3 tools and the total exposure which, at 2.2 m/s2 A(8) or 75 points is below the EAV.

3. Background

Meeting the recommended guidelines and addressing moral issues introduced by the European Physical Agents (Vibration) Directive 2002 was a priority for Leeds City Council Parks and Countryside Service as they employed over 500 personnel working with vibrating equipment. Management commitment guaranteed allocation of resources to investigate, develop policy and implement action plans to ensure compliance with guidelines and achieve a uniform approach across the sector. A HAVS working group was established focussed on assessing the risks and implementing control measures. Management compiled lists of staff that were considered potentially at risk and interviews and training in the risks associated with working with vibrating equipment ensued. Identified staff were subjected to a health screening program conducted by an occupational health nurse who referred individuals with symptoms to a physician for further assessment. Initially health screening was conducted on a biannual basis unless otherwise stipulated by the medical practitioner.

Due to the lack of awareness and general low priority given by manufacturers to the topic of vibration obtaining magnitudes to add to the equipment inventory was painstakingly slow. Machinery was tagged with the allowable maximum exposure durations which were calculated to 2.8m/s2 A(8) and employees were instructed not to exceed the usage levels. Initially it was thought this self-policing measure was sufficient to prevent staff from over exposing themselves to high levels of vibration.

Paul Pitts MIOA then described research in the Acoustics Bulletin September/October 2003 that showed many manufacturers bench tests on tools had a poor correlation with ‘in-use’ times underestimating vibration in real use. The news unsettled Leeds City Council and not convinced they had done everything within their powers to reduce exposure levels they authorised the purchase of a Larson and Davies vibration meter to commence their own ‘in-use’ testing with a view to re-tagging their equipment.

Figure 2. Equipment profiles using vibration magnitudes provided by manufacturers.

Figure 3. Equipment profiles using vibration magnitudes tested ‘in-use’.

Testing was carried out after completion of planned cyclical maintenance schedules as it is well documented that poorly maintained equipment gives out higher vibration magnitudes. Correlating exact ‘in-use’ times also proved difficult as vibration levels altered substantially dependant on factors such as ground condition, travel speed, operator mass, weather conditions, the material being worked on etc. Relevant staff were trained to understand and accurately calculate the vibration readings and the decision was taken to move to the new reduced vibration action level of 2.5m/s2 A(8) prior to 6th July 2005.

In order to test a ten percent representative sample of each type of machine, equipment was grouped into specific types and models and a minimum of three tests were conducted in working conditions on each tool. The results were analysed and the new machinery usage times were calculated and displayed on the equipment.

 

 

 

Figure 4. Employee X’s daily vibration exposure calculated using manufactures vibration magnitudes.

N.B Report and graph displayed in green indicating no risk to employees’ health.

 

 

 

 

 

Figure 5. Employee X's daily vibration exposure calculated with "in-use" vibration magnitudes. N.B Majority of report & graph displayed in amber & red indicating employee requires medical screening to be implemented.

 

 

 

 

The new allowable exposure times were very low and work schedules could not be maintained without the employment of new staff, new machinery, job rotation, re-training to multi-skill the workforce, changes in working programmes and processes and/or re-designing and defining the horticultural areas that were maintained. A consultant was employed to help audit the management of hand arm vibration and his recommendations were taken on board and the policy and action plans revised.

The action plan identified the need to assess individual staff exposure to vibration to ensure maximum usage times were not being exceeded. Forms were created for operators to record the machine type and usage times of equipment on a daily basis. Results were evaluated regularly and it quickly became apparent that actual trigger times were not being captured and exposure duration was over estimated. Operators were not taking into account travelling time to site, breaks, lunches, refuelling etc and were viewing the process as a time and motion study. Completing paper forms in dark and inclement weather conditions was not ideal and forms were often incomplete, misplaced and ineffective for recording multi-tool usage. Collating the data and manually analysing the results of the forms was time consuming and difficult before the use of the HAVS Manager software which instantly highlighted problem areas.

In order to improve the accuracy and simplify the process of recording actual trigger times, work is currently underway with consultants to carry out an extensive survey of a number of key repetitive work activities to collect more accurate data. This data will then be input onto the system as a standard or set exposure rates for these tasks. It is expected that this independent assessment will provide information for over 60% of the works carried out by the Service and will ultimately improve HAV information management.

A training program was devised to specifically educate workers on how and why forms needed to be completed correctly and trigger time studies were conducted for cyclical grounds maintenance and singular work processes to reduce the need for continuous form filling. Work activities and processes were programmed into the system to facilitate risk assessments and help implement control measures.

Although employees had already been issued with HSE Hand Arm Vibration Syndrome Pocket Cards INDG296P and given HSE information on the Health Risks from Hand Arm Vibration Advice for Employees INDG126, it will be re-issued as part of the next phase of training. Signatures will be obtained to confirm understanding and dates will be recorded onto the management system.

The software provides easier and precise evaluations of employees’ exposure levels, which ensures more accurate assessments of employees requiring health screening. As recommended by the new legislation this is now conducted on an annual basis unless otherwise stipulated by the medical practitioner.

Figure 7 Instances of employees breaching daily EAV’s and ELV’s requiring medical screening with ‘in-use’ vibration magnitudes.

Where it is recommended that employees are no longer able to work with vibrating tools they are removed from the task immediately and given the opportunity to undergo the councils ‘managing workforce change’ process to help successful re-deployment which may involve additional training for some or early retirement for others. Out of the 500 operational workers screened for HAVS approximately 60 were diagnosed with symptoms. There have been less than 5 litigation claims received for HAVS and considering previous employment histories creates an element of doubt when looking to apportion responsibility for cause. Although costly and cumbersome pre-employment health screening is now undertaken to ensure the applicant is fit and the work required does not pose a risk to their health.

Risk assessments have now been created for each tool type covering the generic detail of HAVS and the imposed allowable usage times are clearly displayed on all equipment. The use of a small variety of tools previously identified as having excessively high vibration magnitudes have been phased out and vibration levels are now used as part of the selection criteria in the procurement process.

Conducting ongoing site tests with new machinery ensures Leeds City Council Parks & Countryside Service are kept up to date with the latest technological advancements and claims by manufacturers of lower vibration levels. A list of ‘acceptable’ machinery has been compiled and will form the basis of a replacement machinery program authorised for implementation over the next two years.

Clearly affected by the restrictions of working to the legal limits outlined in the Physical Agents Vibration Directive 2002/44/EC there was a need to introduce radical changes in the service provision. This meant political and public opinions had to be considered if employees were to be kept safe from risks of exposure to vibration. In achieving the legal acceptable exposure levels there has been a return to non automated machinery such as rakes and brushes, the introduction of more hard landscaping areas like paths and rockeries, the introduction of job rotation and the need to train litter pickers to operate grounds maintenance machinery.

Leeds City Council Parks and Countryside Service continuously review and audit their HAVS management system to ensure policies, procedures and management practises remain flexible to adapt to changing circumstances.

5. Conclusion

If the manufacturers bench test vibration data is used to determine when medical screening is required there is a substantial margin for error which may prove detrimental to the health of employees. Equally important is the need to capture actual trigger-times to prevent under or over estimation of acceptable vibration exposure levels. The HAVS Manager software simplifies data collation and analysis making it easier to interpret the legislation and prove compliance.

The study also revealed complying with the Control of Vibration at Work Regulations 2005 added costs to the service provision but what was not clear is how the costs compared to the price of negligence or if it was possible to put a price on the health of 500 employees.

6. Acknowledgements

Real working information has been collated to generate the reports and graphs for this study but the names of employees have been changed in keeping with the Data Protection Act. A Full electronic transcript of this paper can be found at www.40th-vibration-conference.co.uk.

7. References

Health Safety Executive Website 2005 – Guide to using the hand-arm vibration calculator. European Physical Agents (Vibration) Directive 2002. Control of Vibration at Work Regulations 2005.