Unstable Slope Management System
WSDOT
was the first agency in the United States to fully develop and
implement an unstable slope management system (USMS).
The USMS is an internal WSDOT database and is WSDOT’s
first truly interactive systems using internet technology and
a GIS application. The
application and database is designed for all participants in
the unstable slope management process to view and enter data
pertaining to their respective job functions. The USMS is
central to the process for management of unstable slopes.
In addition, data from other WSDOT databases such as
TARIS (traffic and accident data) can be downloaded
automatically into the USMS database, while other information
required by other WSDOT databases, such as PATS (Priority
Array Tracking System) can be uploaded from the USMS database. The purpose for this unit is to oversee the USMS database by
providing technical support to users and customers.
At Governor Gregoire's request,
the department undertook an evaluation of slope hazards along
the I-90 corridor near Snoqualmie Pass. Two recent rock slope
failures, one resulting in three deaths, have prompted great
interest by the Governor and Legislators on whether the I-90
corridor widening project (which has some rock-fall areas
within) and other rock-fall risk areas should be
re-prioritized for earlier repair than is currently planned.
View the 1-90
Unstable Slopes Report for the Governor
The concept of developing this system
began in the early 1990’s in order to gain knowledge about
and therefore manage unstable slopes along the state highway
system. In the mid-1990s WSDOT implemented a new project
programming approach for the Highway Construction Program that
involved prioritizing and programming projects based on
defined service objectives.
One of the service objectives within the Highway
Construction Program is preserving the existing highway
infrastructure in a cost effective manner in order to protect
the public investment in the system.
One of the action strategies in this service objective
is to stabilize known unstable slopes.
The funding level for the P3 Unstable Slope service
objective has been set at $30 million dollars per biennium
for10 biennium (20 years).
At the time when the priority
programming approach was implemented at WSDOT there was no
existing unstable slope management system in place in the U.S.
that could be used as a model. WSDOT internally developed a comprehensive management system
that could:
-
Rationally evaluate all known
unstable slopes along WSDOT highway facilities utilizing a
numerical rating system for both soil and rock
instabilities.
-
Develop an unstable slope rank
strategy, based on highway functional class that would
address highway facilities with the greatest needs.
-
Provide for early unstable slope
project scoping, conceptual designs for mitigation, and
project cost estimates that could be used for cost benefit
analysis.
-
Prioritize the design and
mitigation of unstable slope projects, statewide, based on
the expected benefit.
Unstable
Slope Management in Washington State
Guidelines
for the P3 Unstable Slope Inventory and Prioritization Process
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