2014/05/28 Council Agenda Packet

(top of the wall in Figure 8). Another measure employed by BNSF is the passenger rail moratorium imposed for 48 hours following a blocking event due to a landslide. Figure 9. Slide fence on top of a wall along the BNSF right of way (photograph courtesy of BNSF). Selection of the most appropriate mitigation strategies is influenced by many factors that often have little relationship to the factors contributing to the landslide. Some of these include available funds, right-of-way/property ownership, required permits, access constraints, environmental effects and service interruption during construction. Proactive Versus Reactive Mitigation Strategies The mitigation strategies above can be implemented reactively or proactively. Reactive responses are instituted at the time of failure with little to no advanced planning. Expenditures are made when necessary, and are tailored to address actual conditions. No unnecessary expenditures are made on slopes that might not otherwise fail and impact the facility within a reasonable timeframe. However, reactive responses are often required at inconvenient times and locations, and are generally more costly to construct than when the same work is performed proactively at a more opportune time. Also, there are often more barriers to designing and constructing what is most effective and best suited for the site under emergent conditions. Further, direct and indirect costs/impacts — especially those indirect — are more difficult to manage by relying solely on reactive responses. Problems with a reactive management approach for unstable slope impacts to transportation facilities include high public expectations of the reliability, convenience and safety of the system (Lowell and Norrish, 2013). p. 19