This knowledge base article is a takeoff from “Pipeline Toolbox (PLTB) and Vehicles over Buried Pipelines – Maximum Allowable Stress”. These predictions through Spangler’s work, Battelle and others who contributed to validation makes PLTB one of most used programs in the industry. It includes temporary wheel and track load crossings that considers a uniformly distributed load at the surface while calculating the load on the pipe. This article will focus on concrete, asphalt and timber mats as well as other materials such as steel plates and composites. The other materials are not part of the Pipeline Toolbox which will be discussed.
Pavement types used in PLTB:
- Concrete – Rigid – Thickness required – Double Layer
- Flexible – Asphalt – Thickness required – Double Layer
- Semi Rigid – Timber Mats – Thickness required – Double Layer
- None – Soil Depth required – Single Layer
Other Material Types not use in PLTB:
- Air Bridges – Timber Construction – For Extremely Heavy Loads – Specifically Engineered for Sites
- Steel Plates – Used for Small Openings in Paved Streets – Flexible in Soils – Edges Lift Up and Unstable – Difficult to calculate
- Composites – Have Not Achieved the Status of Timber, Concrete or Laminated Wood Mats – No official stress testing completed
Temporary wheel load crossings are designed and evaluated directly from the point loading analysis of Spangler and Battelle.
Temporary track load crossings are designed and evaluated by considering the track to be a uniformly distributed load at the surface and estimating the load on the pipe using the same Boussineq solution that Spangler applies at the pipe crown for point loading at the surface.