Vehicles and edge protection
Transport accounts for 40% of all accidents in quarries and 60% of all deaths. It has been a priority for HSE for many years but until the industry addresses safe vehicle, safe workplace, competent driver and supervision it will not improve. None of the things set out below are complicated and there are some basic things that can be done straight away which will have a significant improvement in the figures. Look closely at your workplace, could this happen to you?
Road vehicles, Your haul roads start at the entrance to the quarry. Can a visitor find their way into the quarry and to a point such as car park or weigh bridge if they are in a lorry? Is their sufficient signage? Cars should not be allowed past the car park. Is reversing minimised? Many loading points are too low for the vehicles that are loaded there. This is not acceptable and arrangements must be made to ensure that vehicles can be loaded without reversing.
If you are loading tankers can they be loaded with the handrails raised or with hand rails fitted to the plant so that drivers cannot fall from the vehicles.
Are sheeting bays provided at all sites? Vehicles that need sheeting should be fitted with sheeting systems that operate from the ground. However there will always be a need for trimming loads or where the sheets get stuck for access to the top of the vehicle and a sheeting bay with fall arrestor should be provided at each site. More information on sheeting is given in the section on working at height.
Have you considered whether the road vehicles and site vehicles need to mix? Can the road vehicles be held in a holding bay until they are needed at the loading point?
Can they be separated from the site vehicles. What special precautions will be taken where they have to cross?
Are the road surfaces suitable for road going vehicles. Tipping points for road vehicles should be level. These vehicles particularly articulated vehicles are prone to overturn if there is a cross grade, if the tractor unit is not straight with the cab (on articulated vehicles) or where sticky loads are being transported.
The driver of this articulated vehicle was killed when trapped by his cab when it overturned and trapped him.
Although site vehicles are big and tough, they frequently overturn or are in collision with one another because they are being used in the wrong conditions. It is essential that these basic rules are observed. You should check your site rules to ensure that they can be used safely. Always wear your safety belt, it would save 25% of all fatal accidents at quarries.
Collision of 2 sales vehicles on quarry access road, not driving to weather conditions.
It is essential that these basic rules are observed. You should check your site rules to ensure that they can be used safely.
Road widths. Roads need to be wide enough to allow vehicles to pass with ease, or if they are narrow one way working or traffic controls will be needed such as traffic lights. For single track roads they should be a minimum of two times the width of the largest vehicle. For two way roads they should be three and one half times the width of the largest vehicle using the road. The dimensions above are the minimum acceptable widths.
Large dump truck "nudged" land rover after starting from stationary position. Foreman parked land rover in blind spot for dump truck driver when plenty of room available in front of vehicle
Dump truck running with raised body. This matter should be addressed in the vehicle rules.
Road gradients are often misunderstood. For rigid vehicles they should not exceed 1;10. This is not the same as 10 degrees. The following diagrams illustrate this. Brake testing results are measured in % g and can be readily adapted to the use of % gradient above. For example a vehicle with 20% g brake efficiency would not stop on a slope of 1:5. Thus having designed your roads you have to chose a vehicle that is suitable to work within your design parameters or change your design. A 10 degree slope is equivalent to 17% which is a lot steeper than a 10% slope and would be too steep for older dump trucks to stop on!
The failure to provide adequate edge protection is the cause of many of the vehicle incidents in UK, and is the most common comment made at HSE inspections. The recommended height is 1.5m or half the height of the largest wheel using the road or tip which ever is the greater. As a rule of thumb if you can see over it is probably not high enough. This recommendation is the minimum that is required and acts as an edge marker to warn the driver of the vehicle. To stop the vehicle going over the edge higher berms are required. These should be installed in areas where it is likely that a vehicle may go through the edge protection.
This vehicle drove through 1.5m high edge protection because it approached it at right angles. Higher protection as set out below would have stopped it.
For an eighty five tonne vehicle or less tests have shown that you need a berm of three times axle height.
For vehicles of greater capacity than 85 tonnes a height of four times axle height would be required. When designing road ways this should be considered for areas where the vehicles are likely to run through edge protection.
For the majority of cases the normal heights recommended will be adequate as they are sufficient to overturn the vehicle back onto the road. (another reason to wear seat belts)
Edge protection should be built out of materials such as scalpings as in the diagram above
Edge protection should be built on a good foundation. Sand pushed off the edge of the road will be to soft to work and gives a false sense of security.
Many of the tipping accidents occur when the rear wheel of the vehicle on the opposite side to the driver goes over the edge and the vehicle falls off the tip. To prevent this happening the following should always be followed:-
(i) Never reverse towards the tip edge unless adequate edge protection is provided. A minimum height of edge protection of 1.5m or half the wheel diameter which ever is the larger must be provided.
(ii) In Britain some vehicles have their cabs on the left and some on the right, others are in the middle of the machine. Therefore always reverse at right angles to the edge protection.
(iii) Never reverse with the wheel diagonally opposite to the driver approaching the edge protection first. Too many drivers have been killed doing this.
(iv) The edge protection must be provided on the stable part of the tip - edges will fall away as the ground stabilises.
(v) Visibility must be sufficient for the tipping operation, with all round vision provided to the driver and adequate lighting if used at night. In poor visibility such as fog then tipping must be suspended.
Whether you are driving a road or site vehicle you must only tip on stable ground without a cross gradient. You should not tip down hill as if the load gets stuck it will tip the truck over. The best is to tip uphill on a slight gradient.
Edge protection can be purpose built crash barriers or made from suitable materials such as scalpings. Boulders on their own are not suitable as edge protection but they can be used to delineate haul roads around flat areas of the quarry.
The diagrams shows that edge protection should be a minimum of 1.5m (5 feet) or the radius of the wheel ie half the diameter of the wheel or the axle height which ever is the larger.
The front profile of the edge protection should be made so that the vehicle will not drive up and over.
Remember that edge protection can deteriorate due to weathering, so it must be properly maintained and inspected under the inspection and maintenance scheme.
The purpose of the edge protection is to warn the driver that the edge is there. It works by catching the vehicle or by overturning it back onto the road. To do this it has to be well constructed and sufficiently large to absorb the momentum of the machine. Part of the tip and excavation rules will have to determine the size of edge protection you intend to use and where. HSE guidelines state that it should be 1.5m or the radius of the wheel which ever is the larger for most use. On ramps etc. you may need to put higher bunds in place.
Work in the USA shows the heights that are needed to stop the equipment. Experience in the UK shows that the standard measurements recommended by HSE are effective at delineating edges of roads and tips. A site risk assessment will identify areas where increased edge protection is needed.
The workplace regulations require the quarry to have adequate traffic routes. This means that the roads have to be wide enough for the vehicles that are using them. It is essential that reversing is minimised and where vehicles cannot pass easily, the roads should be one way or have traffic controls.
The diagram shows the widths required.
Roads have to be adequately constructed to be suitable for the vehicle using them. This means they need to be well drained and surfaced with suitable materials. This not only improves safety but also productivity.
No edge protection has been provided
This quarry has not been properly planned and designed
No edge protection
This sand is being pushed off with a wheel loader, note no edge protection and how close the wheels are to the edge of the tip
Inadequate edge protection at this sand quarry