Transportation infrastructure is one of the most widespread and severe anthropogenic impacts on human health and the environment. Transportation planners should not ignore the ethical ramifications of the global transportation network. Since the 1960s the field of transportation engineering has increasingly integrated a responsibility for human safety in addition to the primary goal of transportation efficiency. Current standards evaluate trade-offs between the competing goals of, for instance, speed and safety. Because such evaluations recognize the moral obligation to provide a level of safety for drivers and pedestrians, transportation decision-making necessarily engages in ethics, albeit tacitly. In this sense, roadway users are part of what ethicists term the "moral community," or the collection of beings that are held in moral regard. More recently, the field is recognizing the broader impacts of transportation on human health and economic impacts to roadside communities, historical preservation, and landscape aesthetics. While still the exception, rather than a rule, this type of context-sensitive design process expands the moral community involved in decision-making beyond roadway users. In a similar way, the growing recognition of the environmental impacts of transportation further enlarges the moral community. By considering negative environmental impacts and weighing these against other factors like cost, efficiency, and safety, wildlife and habitats can be granted moral consideration in project decision making. However, this increases the complexity of ethical decision-making. Whereas, a decision between speed and safety can be considered as a trade-off in one dimension, each successive expansion of the community and associated values exponentially increases the complexity of evaluating multi-dimensional trade-offs. We argue that the field of road ecology, poised at the intersection of road engineering and environmental conservation, is well situated to help develop explicit ethical decision frameworks in transportation planning. We propose that, as a first step, the field of road ecology should explicate its own Ethic of Road Ecology. For example, wildlife exclusion fences along roads are beneficial for human safety and reduce unnatural wildlife mortality, but they also represent a monetary cost, affect landscape aesthetics, and - when they are not combined with safe crossing opportunities for wildlife -- also result in further habitat fragmentation. We draw on the field of ecological restoration for examples of field-specific ethics.