Day Lighting

What does Day Lighting Mean?

Definition of Day Lighting in Construction
The technique of excavating for utilities, at certain predetermined, sequential locations, to determine the depth and actual location of the suspected utilities.

Normally this day-lighting function is performed by a non destructive form of excavation such as a hydro excavator. The day-lighting procedure once completed, allows the use of a more aggressive form of excavation, to more effectively excavate utilities, without the need to blindly excavate. Once the day-lighting is performed, the utilities are located and marked, the threat of breaking them has been substantially reduced.

Day lighting is extremely important when the excavation is for an important electric or gas line, which could have devastating consequences if struck and broken. In addition, the use of fiber optic cable to transmit signals has caused the popularity of using the day-lighting technique to increase. The insurance liability as well as physical problems caused by the breaking of a major fiber optic transmission cable can be in the millions of dollars. Day – lighting is a technique that is growing as liabilities grow. The actual technique is extremely simple, the assumed route of the utility is marked off on the surface of the ground. This location could be anticipated by an as-built drawing, a previous construction underground drawing, electronic surveillance, or other means of estimating where to find the utility. Once the surface is marked out, and dependent upon the engineering data, a spacing for the excavations is decided upon. If the spacing is to be every 50 feet, an excavation, or hole, is dug every 50 lineal feet along the assumed route for the utility. This excavation is initiated until the utility is physically found and marked. Once the utility is found and marked, the intended route of the utility is either modified in accordance with the actual visual confirmation of the utility, due to the day-lighting, or the route is verified and the day-lighting then occurs another 50 feet up the route of the utility. This procedure continues until the accurate marking of the utility line is completed.