## ii. Pollution

In the context of the Belt and Road Initiative, new or upgraded highways or rail will be built primarily with the intention of increasing freight traffic, with the secondary effect of potentially increasing passenger traffic. In terms of roads, it is expected that increased high‐speed freight truck traffic on new and upgraded BRI highways will generate significant noise and air pollution including greenhouse gases (GHGs). Water pollution will also be created from metal corrosion, tire wear, exhaust emission, trash and other pollutants that are washed into waterways, especially during heavy rainstorms or floods when drainage capabilities of ditches and soil are exceeded (Economic Commission for Europe 1975). Measuring pollution requires data on volume and composition of traffic as well as the weight, speed, and efficiency of the cars and trucks (Janic and Jovanović 2012). Assessing the increase in pollution from the new or improved BRI is more complicated, however, as it also requires identifying induced demand for highway travel and transport, displacement of traffic from other routes, and substitution between different modes of transportation. These issues will be discussed below in the Indirect Effects section.

With regards to pollution from BRI rail projects, conventional rail typically has higher emissions per passenger or per ton freight than high‐speed rail because the latter is predominantly powered by electricity rather than diesel. HSR emissions are directly related to the sources used to generate electricity and their energy consumption. If significant coal is used as the source of the electricity, then HRS can contribute significantly to local air pollution around the coal plants through the production of SO2. However, in general both conventional and HSR contribute significantly fewer GHGs per passenger or freight than other forms of transportation such as road, air transport, and waterways (Givoni 2006; X. Li, Fan, and Wu 2017; National Rail 2009; Viana and Cenamo 2008). Conventional freight rail has two to five times higher fuel efficiency than truck transport (Dorsey, Olsson, and Rew 2015), as well as uses 21% less energy per passenger mile (Federal Transit Administration 2009). In Europe along the Mega‐ TransEuropean transport corridor, the substitution from trucks to freight trains resulted in 64‐70% savings in GHGs (Janic and Jovanović 2012). Train are even more efficient than airplanes. As compared to air transport, HSR have lower emissions of CO2 and NOx. Moreover, NOx emissions at high altitude affect climate change much more than ground‐level emissions, making air transport even more damaging (Givoni 2006). As with roads, the ultimate pollution impact from a BRI rail project will depend not only on the relative fuel efficiency and pollution controls, but also the induced traffic demand that could increase overall pollution, which will be addressed in the Indirect Effects section below.

Noise pollution from trains (freight and passenger) has also been recognized as harmful to the health of humans and wildlife populations. For freight trains, the longer, heavier, and faster trains generate higher level of noise but exposures are shorter due to higher speeds (Givoni 2006; Janic and Jovanović 2012).

# B. Ecosystem Effects

i. Habitat Loss The most basic environmental impact from a road or rail is the destruction of habitat to create a transportation corridor. The direct loss in habitat due to the footprint of roads and roadside is typically 1‐2% of the land cover of most countries, with a greater proportion near urban centers and the lowest percentage in the less developed landscape frontier (Forman 1998). Habitat loss is closely correlated with many accompanying environmental risks that are related to loss of ecosystem services such as biodiversity habitats, carbon storage and sequestration, water provision and quality, soil stabilization 6