When you think of a prism, a rainbow easily comes to mind. Water droplets form a type of prism to reflect, refract, and disperse light that results a multi-colored arc. Surveyors think of something else. A surveying prism sets a control point for the rest of the points located at a project site and is an important surveying tool that has a major impact on the quality of your measurements. Conventional prisms are tripod mounted and placed on the ground in an advantageous spot. In most cases, they have to be moved numerous times over the course of a project. In one of our current projects, DAA come up with a solution that added a safety bonus.
A 360 degree prism
Surveyors Dereck Perry and Johnathan Vaughan, from our Charlottesville office, set 360-degree prisms on rooftops of four adjacent buildings for the UVA Hospital Expansion Project. The prism, put in a remote placement, should be able to remain stationary for the entire project. This will help to achieve accurate point control throughout the duration of the project and save time on setting up and breaking down a conventional tripod-based prism.
The placement, however, created challenges. Mainly, hanging over a roof edge nearly 100 feet above the ground to place the prisms. It created a fall hazard to our employees and to any pedestrians that passed below. That’s where our Safety Manager Guy Butts stepped in. By creating a custom fall protection class which met all of OSHA’s regulations, Dereck and John were able to get the job done.
Each employee donned a Miller Full-Body Harness and was attached to a retractable life –line and fall restraint life-line.
Even though the sidewalks below were blocked to eliminate the risk of a by-stander from being hit by a dropped tool, restraint devices were attached to each tool and bracket that were placed over the edge of each building to keep them from falling.
We were able to hang our rainbows for Skanska/UVA Medical with each of our guys 100% secured, per OSHA Fall Protection requirements with peace of mind that everyone above and below were safe.
