Rockfall and rock slope design engineering guidelines
have been established since the 1960’s with such notable works as the Ritchie
Ditch Catchment (1963), Rock Slope Engineering (Hoek and Bray, 1974), Rockfall
Catchment Area Design Guide (FHWA-OR-RD-02-04), and more recently Rockfall
Characterization and Control (Transportation Research Board (TRB), 2012).
These guidelines offer the basis for design of rock slopes and rockfall
catchment but do not establish guidelines, criteria, or metrics for
implementation that designers or agencies can follow.
Given the desire to make
and communicate asset management based design decisions, and to design for
resilience and the consideration of life-cycle cost, there is a need to develop
a rock slope and rockfall guideline metric and framework that establishes suggested
parameters and protocols based on:
Rock slope evaluation to determine potential
for generating rockfall by either a condition, tolerable risk, or performance
based systems or combinations therein,
Rock slope mitigation options such as blasting
methods, stabilization, or protection measures or combinations of each to
reduce the potential for rockfall,
Ditch catchment options based on rock slope
evaluation, mitigation options and traffic volumes,
Formulating an iterative life-cycle process to
evaluate and encompass roadway design, constructability, environmental, cost,
maintenance, and other considerations using the previous points including potential
for rock slope to generate rockfall, mitigation options, and ditch catchment
Results of the research
will be useful to transportation agencies charged with managing rockfall
DOT agencies have a wide range of methods or procedures from prescriptive to
non-existent for evaluating rock slope blasting, rock slope mitigation, and rockfall
ditch catchment within a corridor that has led to questions with performance,
liability, standards and other issues between agencies, designers and
practitioners. Clarification and further
refinement of design procedures will provide a more functional design process
with consistency among agencies.
parties would be able to communicate consistently on the basis for design and
the expectations for performance in terms of conditions, risk, resilience and
life cycle cost. The value of the designs
and mitigation actions with respect to the performance of a corridor would be
able to be demonstrated.
The following tasks are necessary to achieve the stated
1. Evaluation of previous Rockfall Hazard Rating
Systems (RHRS) or modified rating systems to evaluate and assess the potential
for a given rock slope to generate rockfall.
2. Review various rock slope mitigation options based
on rockfall potential. Slope mitigation
includes such items as blasting, bolting, draped mesh, and pinned mesh.
3. Evaluate rockfall catchment relative to rock slope
4. Evaluate rockfall catchment percentage needs
based on such factors as traffic volumes, roadway layouts, slope mitigation, ability
to maintain, and others for a given corridor.
5. Determine performance measures and metrics for
various design combinations.
6. Prepare a report detailing the results of
items 1 through 5. Recommend an evaluation system to assess the condition of a
rockfall system, and provide recommendations for evaluating and maintaining
existing rockfall protection systems in a format suitable for adoption by
|Index Terms:||Rockfalls, Rockslides, Metrics (Quantitative assessment), Guidelines, Rock slopes, Plan implementation, Life cycle analysis, Geometric design, |