A Mirror’s a Mirror and a Sensor’s a Sensor, Right?
A comparison: safety mirrors vs. motion sensors vs. motion sensor mirrors
Every facility has its own devices, equipment, and programs to promote safety. There are signs, strobes, beeps, mirrors, bright colors, vests, id tags, and more. When it comes to seeing a hazard approaching, or being able to see what’s around the corner, it can be hard to determine which technology works best. That’s why I decided to take a look at the advantages and disadvantages of two widely used technologies and one fairly new one. Let’s see what can be gained with each, it’s best application, and what you might miss.
 Safety Mirrors: a widely used, economical visibility solution
We see safety mirrors in more places than just warehouses now days. You see them in pharmacies, offices, hotels and supermarkets. They have vastly decreased the number of collisions due to blind corners and busy intersections in buildings. They also have a few drawbacks that keep them from being the total solution to collision prevention.
Pros:
- Domes and convex for wider angle of visibility
- Helps users see activity in aisles and traffic lanes at intersections
- Very economical
- Also provide a measure of security monitoring
Cons:
- Hard to distinguish details
- Easy to miss subtle motion
- Mirrors tend to blend into background of warehouse environment
- People aren’t alerted and must look for motion on their own
Warehouse safety sensors detect the slightest motion
A newer technology than safety mirrors, motion detection sensors have seen a rapid rise of use in warehouse environments. They “scan” a particular portion of the warehouse and when motion is detected within that scan range, special programming triggers various events to happen such as flashing lights or audible alerts. Highly efficient in detection abilities, they also have some ‘blind’ spots.
Pros:
- Detects motion of any kind
- Can trigger warning lights
- Can detect motion at blind intersections
- Audible alarms can be added
- A broad variety of solutions means there are standard models for every situation: rack aisles, dock doors, corners, plant entry, hallway/doorway, and other standard configurations are available
Cons:
- Compared to warehouse mirrors, you can’t see what causes the motion detector to trigger
- In some situations, when all motion is detected, workers can begin to disregard frequent alerts
Sensor mirrors – a hybrid that combines the best of mirrors and sensors
This technology combines the advantage of the wide angle visibility of safety mirrors with the scanning technology of motion sensors, resulting in an effective hybrid device with all the pluses of both technologies. Additionally, they have a higher ‘respect’ rate than sensors alone because sensor mirrors are selective in their detection schema. That means users may not consider them ‘background’ and disregard them. They may not disregard the warning if it’s issued less frequently.
Pros:
- Dome and convex mirrors provide high visibility around corners and at intersections
- Sensors detect industrial vehicle traffic only – pedestrians aren’t warned of other pedestrians, just vehicles, providing more certainty in what is causing the motion on the other side of a corner or aisle
- Bright “CAUTION” lights with directional arrows are triggered to indicate where the vehicle is coming from
- Audible alarms can be added to enhance the flashing text warnings
Cons:
- They’re more costly than either mirrors or sensors (dependent on configuration)
- Since they do not detect pedestrians, vehicle drivers are not warned of the presence of workers afoot
So, now you know what works and in which situations. Assess your facility and consider which technology will serve you best. Typically, a mixture of these technologies will provide a comprehensive pedestrian/forklift safety solution. It’s not one size fits all.
Tags: alert, warning, arrow, caution, Safety & Ergonomics, industrial, sensors, vehicle, forklift, mirrors, detection, motion
Scott Stone is Cisco-Eagle's Vice President of Marketing with more than thirty years of experience in material handling, warehousing and industrial operations. His work is published in multiple industry journals an websites on a variety of warehousing topics. He writes about automation, warehousing, safety, manufacturing and other areas of concern for industrial operations and those who operate them.