which include analyses of alternative routes to avoid environmentally sensitive sites. For example, in its planning of the recently completed HSR Guiyang‐Guangzhou Railway Project, the Chinese government identified 47 environmentally sensitive sites that included protected areas, forest parks, scenic areas, watersheds, and cultural relics sites. In the project feasibility study, planners created many alternative routes and the route selected avoided 40 of those sensitive areas (Wang, Yang, and Quintero 2012).

# II.  REDUCE: After Projects/Routes Selected

If avoiding risks is impossible, then reducing<sup>6</sup> environmental risks should be considered, as suggested by Ekstrom and colleagues (2015): “Measures taken to reduce the duration, intensity, significance and / or extent of impacts (including direct, indirect and cumulative impacts, as appropriate) that cannot be completely avoided, as far as is practically feasible.” Reductions in the environmental risks of a project below thresholds of harm may be possible. If not, actions may reduce the scale and the expense of the remediative measures, such as restoration or offsets, that may be required later for unmitigated loss.

Risk reduction via project and route selection has been introduced above, within the Avoidance section. For some infrastructure projects, such as the HSR Guiyang‐Guangzhou Railway Project, China, described above, there can be an overlap between decisions to fully avoid impacts versus partially avoid impacts, i.e., reduce impacts. In that example, railway planning completely avoided 40 sensitive sites yet broadly it would also be right to claim risk reduction by 85% (40 of the 47 sensitive sites). For this case, actions could be considered “avoidance” or “reduction” but we will not repeat the avoidance discussion here.

Instead, for the rest of this section on reducing risks, we will consider several other reduction decisions for BRI transportation projects. First is the selection of techniques during infrastructure construction and operations. Second is the use of complementary policies that could change the impacts of investments.

Just as for avoidance, reductions should be proposed during early project feasibility studies (additional options will likely be identified through EIAs). There are many strategies to reduce direct environmental impact during construction and, to a lesser extent, operations of roads and railways. Many concentrate on adjusting the design of the infrastructure, but others focus on location and timing. Here we list just a few examples that address reducing the impacts from a range of different environmental direct effects. An exhaustive review of strategies to reduce impacts is found in van der Ree et al. (2015). Prescriptive good engineering design strategies are also detailed in voluntary sustainable infrastructure standards developed by organizations such as SuRe®, CEEQUAL, Envision®, and Greenroads® (see Part 3 and Appendix 15).

A. Local Strategies for Reducing Direct Effects: Good Engineering Design Strategies to reduce local direct effects such as abiotic and wildlife impacts from investments in transport often have been focused upon changes to the design and the construction of infrastructure. Good engineering design solutions at both the project and landscape level are among the most frequent strategies to address hydrologic, sedimentation, and erosion dynamics. For example, tunnel‐bridge‐ tunnel engineering schemes can be instituted to avoid dangerous landslides or erosion along steep

> 6 The term “minimize” also is often used alongside or instead of “reduce,” for the second element of this mitigation hierarchy. As it is hard to minimize more than one objective, and as truly minimizing means avoiding, we use reduce as our default.

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