Railroad ecology
Railroad companies routinely clear-cut and/or spray with herbicide any vegetation that grows too close to the tracks.
On overhead electrified railroad lines, clear-cutting must be more extensive, vertically as well as horizontally, in order to prevent vegetation (especially tree limbs) from interfering with the pantographs on a moving train, breaking off and falling on the wires, or simply from arcing in proximity to high voltage transmission cables.
The same vegetative selection processes described in the previous paragraph apply, but may additionally favor climbing vines due to the presence of catenary and transmission poles in addition to the wooden communications and signal pole lines which often exist(ed) along nonelectrified lines.
In North America, such species include trees such as Ailanthus altissima, Paulownia tomentosa, Siberian Elm, and Norway Maple, and invasive non-woody plants such as Japanese Knotweed and Phragmites.
The railway tracks provide corridors along which these species can spread and thrive, even when the surrounding areas might be less hospitable to them.
[1] These railway verges can extend for multiple kilometers without being interrupted, creating a corridor for species to disperse.
Additionally, when constructing a new railway, vegetation is removed, soil is bared, and water is managed, creating ideal conditions for invasive plants to implant.
[10] Railways and powerlines to supply electrical trains, like other linear infrastructures, divide habitats when built.
[3] Some species, such as the eastern box turtle and other types of herpetofauna, are unable to physically cross rails.
Pollution due to diesel engines, sound and vibrations can prevent wildlife from crossing train tracks.
[8][3] Caribous have a higher chance of being preyed upon by wolves when located near linear infrastructures, of which railways are a part of.
[11][12] There are many different railway mitigation measures, most of them fit into two main categories: either to prevent animals from being on the tracks or reduce the barrier effect.
[13] Culverts can be adapted during their construction or afterwards to better allow wildlife to use them as crossing structures by including dry ledges, modifying the habitat at the entrances, avoiding slopes or steps, etc.
[14] Wildlife underpasses and overpasses are also good ways to reduce the barrier effect of railways, but they are associated with a much higher cost of construction.
[13] The rock between two railway sleepers can be excavated to allow small mammals and herpetofauna who are unable to physically cross rails to do so.
[13] They also need to include areas for animals trapped in between the exclusion fences to escape into the surrounding habitat.
[13] In the case of roe deer, sound signals make this species run towards the railway track, where the trains cannot avoid the collision.
Trains typically are on a singular track, they cannot swerve to avoid a collision and their capacity to slow down is very limited.
There is a large proportion of electrical trains, leading to lower emissions near tracks than gas vehicles on roads.
