In the majority of applications the incoming trucks back into position level at a 4’ elevated loading dock area. The 4’ elevated loading dock area is achieved through a combination of building design and site grading during the building construction.
There are some sites that initially have grade level loading only. Converting a site with grade level loading to a site with a 4’ high loading dock involves site excavation and grading. Starting at floor level the Contractor excavates down 4’ at the exterior foundation wall at the loading dock area.
A declining ramp is then constructed to allow the trucks to back down the ramp to the 4’ high loading dock, the bed of the truck is now level with the loading dock floor. The overall length of the approach ramp determines the percentage of decline, the longer the approach ramp the lower the percentage of decline.
To prevent the top of the trailer from making contact with the building wall before the bed of the trailer contacts the dock bumpers the dock leveler pit and the dock bumpers are projected or cantilevered forward during the time of construction.
This link leads to a description of a declining loading dock approach and a projected pit.
https://www.pentalift.com/wp-content/uploads/2020/11/Projected-Pit-Dock-leveler-Benefits-1.pdf
If the decline is calculated to be 6% the dock leveler pit should be projected a minimum of 6” beyond the face of the foundation, if it’s a 4% decline project the pit 4” etc. When projecting the pit ensure that both sides of the pit wall where the dock bumpers are to be installed is also projected forward the same number of inches.
In a declined approach the vehicle restraint may have to be projected as well. The face of the foundation wall is vertical; with a declined approach the incoming trucks Rear Impact Guard will be angled further away from the foundation wall than with a level approach.
Depending upon the model of vehicle restraint and the percentage of decline the vehicle restraint may have to be moved forward to keep the “back to front” proper operating range of the vehicle restraint.
The recommended first step is to contact the Pentalift Sales Department and request a Loading Dock Area Site Survey Sheet. When the Site Survey Sheet is completed and returned Pentalift will make the recommendations to ensure that the loading dock area will be both functional and more importantly safe during operation.
For additional information on any Pentalift product please contact the Pentalift Sales Department.