All can affect production levels, and all are improved by increased operator visibility of the ground area surrounding the equipment from the time of start up and first move of the vehicle, through operation of the vehicle for the shift of the equipment operator.

There is great concern among mine operators that current mirror systems being provided by the equipment manufacturers do not provide the necessary view required by the operator. The view provided is so distorted that the images become useless to the operator in judging distances and immediate recognition necessary for safe operation of the vehicle. 

This concern is evident by the findings of the “Round Table” (EMESRT) sponsored by the Mineral Industry Safety and Health Centre at the University of Queensland in Australia.

The “Round Table” critique of existing mirror systems produced the following conclusions:

The following existing design problems were causing problems with equipment operation and require corrective action.

1.   Walks, handrails, and other external objects located or designed so operator vision is impeded. (including line of site to the mirrors)

2.   Blind spots to the operator during machine start as well as during operation.

3.   Rear vision mirrors that distort the driver’s vision; Mirrors located in such a way that they cannot be safely adjusted and cleaned.

4.   Insufficient number and type of mirrors to see both on the drivers and off driver’s side.

The following photographs serve to illustrate the problems outlined that were found to need correction.

Figure 1       Typical mine truck with factory attached 12” by 20” convex mirror. The driver is not able to see the ground until 16 feet out on the drivers’ side, 105 feet out On the passenger side, and 50 feet out from the front of the truck. Pick-up trucks, machinery and people could be in the area at start-up time or during operation of the vehicle and never be seen by the operator.

Figure 2       Typical large front end loader used in the mine mirrored with factory 12’ by 20” convex mirror and illustrates the distortion of images the operator is viewing Note also there is no means to adjust the mirror so the operator could see something other than the rear of the machine

Both pictures also illustrate the difficulty of adjusting and cleaning the mirrors. All currently offered mirrors require the loosening of adjustment screws while the driver is hanging over the railings some 20 feet above the ground and falls are inevitable. To address this problem some mining companies are going so far as to taking the vehicle out of production to have maintenance come out to make the adjustment and some companies are including harnesses to protect the operator from falling while he/she is making mirror adjustments.

In arriving at a solution, all of the above problems should be considered along with factors that are inherent in the mine and in dealing with the operation of big equipment as follows:

·       Roadways and work areas change constantly in the mine

·       Because of the size of the vehicles, operators must be prepared to take action well in advance of the required response of the vehicle.

·       Visibility is curtailed by the sheer bulk of the vehicle

·       The difficulty of watching all the gauges and controls while at the same time viewing the outside perimeter of the vehicle

Figure 3	Figure 4
Bottom mirror is standard mirror 12”x 20” convex mirror offered by equipment manufacturers. Top mirror is 15”x25” M-C Mirror. Clarity of objects seen is clearly illustrated	Illustrates the field of view and the clarity of the M-C Mirror on a quarry truck