Estimating and Contracting Rock Slope Scaling Adjacent to Highways

NCHRP Synthesis 20-05/Topic 50-13 [Active (Synthesis)]

Scaling loose rocks from slopes adjacent to highways is an effective measure for reducing the risk of rock fall. Removal is typically done by hand using pry bars or with mechanical assistance such as jacks, hydraulic splitters, air bags, or heavy machinery. In some cases, trim blasting techniques are considered as part of a scaling program. Slope access is generally accomplished by personnel on foot and by rope access; however, telescopic boom-lifts and crane baskets are also used. 

Scaling is typically done after sudden or prolonged rock fall activity. However, with the aging of the nation’s highway system, there is an increasing need to address long-term weathering of constructed and natural slopes along highway corridors. The required frequency of scaling depends on the slope characteristics, geology, rock structure, local climate, performance expectations, consequences of rock fall impacts, and budget availability. Some departments of transportation (DOTs) have developed programs for scaling that are performed at regular intervals on a proactive basis. 

The objective of this synthesis is to document current practices for rock slope scaling next to highways. The scope includes documenting methods used by DOTs for specifying, estimating, and contracting scaling and debris removal, and assessing scaling performance.

Find out more about  information on NCHRP Synthesis 20-05/Topic 50-13 at  TRB’s Website.