RATIONALE. Measures to reduce disturbances
Disturbances caused by transport infrastructure and its associated traffic have impacts on biodiversity. Artificial lighting, noise, and chemical pollution reduce habitat suitability, increase barrier effect, and can even increase wildlife mortality (Sordello et al., 2019; 2022). These effects reach distances far beyond their source, affecting adjacent habitats and even protected areas (Jechow et al., 2020; Mu et al., 2021; Sordello et al., 2022).
Light pollution has been demonstrated to create impacts on ecosystems, affecting flora and fauna, both diurnal and nocturnal species (Knop et al., 2017; Falcón et al., 2020; Touzot et al., 2021; Sanders et al., 2021; Meng et al., 2022; Sordello et al., 2022). Moreover, the use of extensive artificial lighting to increase road safety is not always justified as some studies have found little or no evidence of any such relationship (CEDR, 2009; Steinbach et al., 2015; Marchant et al., 2020).
Within transport infrastructure the presence of light, either from vehicles or from the infrastructure itself, reinforces habitat fragmentation (Barré et al., 2020; Sordello et al., 2022). Several species from different groups have shown a general avoidance of light in the infrastructure (Degen et al., 2016; van Grunsven et al., 2017), including avoidance of underpasses which are provided with lighting (Bliss-Ketchum, et al., 2016; Barré et al.,2020; Bhardwaj et al., 2020b).
The need to establish ‘dark corridors’ as an ecological network for nocturnal wildlife has been proposed as a measure to enhance ecological connectivity (Challéat et al., 2021). The timing and location of lighting within these networks must be carefully considered in order to be truly effective.
Traffic noise has also been demonstrated to affect many biological functions, like communication or reproduction, in a wide variety of species (Sordello et al., 2019, and references therein). Usually, noise mitigation measures are implemented to protect people from disturbance, since noise has negative effects on human health (EC, 2002). International transport organisations, such as CEDR, PIARC and UIC, have developed different solutions in this framework (CEDR, 2012; PIARC, 2013; 2019; UIC, 2021). These solutions can be extended to natural protected areas or any other area important for ecological connectivity, such as ecological corridors.
Traffic and maintenance of transport infrastructure produce numerous chemical substances that pollute surrounding habitats. Reduction of carbon emissions by cars is a main focus, but there are other initiatives necessary to reduce or avoid the spread of pollutants, for example by treating water runoff from roads (CEDR, 2016).
Chemicals used in the maintenance of vegetation in verges and medians is another source of pollution. Projects like TRISTRAM (UIC, 2021) provide alternative sustainable methods for vegetation control. While this project’s focus is on railways, its findings and recommendations are relevant for to and can be extended to other transport modes.
Some of these disturbances can also be mitigated by managing traffic. Measures like temporary road closures, usually implemented to reduce roadkill in specific seasons, also eliminate other disturbances. Similarly, lower vehicle speeds reduce the animal vehicle collision (AVC) risk as well as producing less noise. Therefore, measures aimed at modifying driver behaviour, such as road narrowing or alerting drivers, for example with optical pavements, can contribute to reducing both impacts (Hussain et al., 2021).