Transport systems are significant causes of environmental degradation because they generate harmful greenhouse gases, pollute the atmosphere and air, create noise, consume land and cause energy waste due to congestions. The issue of mixed transport systems, in which road and rail modes are simultaneously present and interact, cannot be assessed separately of one another with respect to environmental impacts and energy consumption. The cross-modal assessment should be an integrated step, useful in facilitating a sustainable mobility transition and ill-informed policymaking. This chapter elaborates on the assessment approaches towards environmental impact, energy management tactics and tools of policy that apply to mixed road-rail transport systems. The focus is made on the boundaries of emission accounting, air quality exposure analysis, energy management of demands, integration of renewable, and governance. Policy assessment evaluation frameworks and policy assessment decision-support tools are also discussed and the difficulties and future of the policy direction is also analyzed, focusing on equity, behavioral components, as well as the new carbon governance mechanisms.