AbstractA reduction of negative environmental impacts in urban transportation (air pollution, energy consumption, etc.) is thought to be crucial in promoting sustainable development outcomes in cities, however evidence shows that this objective is hardly achieved in practice. In the case of urban transport planning, the transition to sustainability requests that its performance must be assessed. This has originated important challenges for the academia in providing efficient assessment tools. As a response to these challenges, sustainability assessment has become a rapidly developing area associated with the family of impact assessment tools ((e.g. Environmental Impact Assessment and Strategic Environmental Assessment). In recent years, many countries have conferred to sustainability assessment, and specifically to Environmental Impact Assessment (EIA), an important and decisive role into their planning systems.The effectiveness of the traditional methods for evaluating urban transport plans/interventions (e.g. EIA, EAE, Cost-Benefit Analysis) is contested as strongly argued by several academics. A key problem is that these methods currently focus too much on identifying environmental impacts that might happen rather than on finding ways of preventing them from happening. They are used reactively rather than proactively. Underlying this is the belief that traditional evaluation methods have difficulty guiding improvements in urban transport plans and projects in decision-making and their capacity to support technical decisions becomes limited. First, this is a consequence of the fact that the environmental assessment (EA) process mainly includes EA-makers and they are not integrated enough in the transport planning process. Second, the used methods not always are the most suitable to identify ways of preventing potential impacts with respect to the particular nature of urban transportation.In seeking to answer these problems, the paper presents a strategy for proactive environmental instruments design. Accordingly to this strategy, EA instruments must fulfil two key criteria: i) be spatial integration-oriented; ii) be performance and threshold-based. The strategy is presented here as a complementary vision to traditional instruments. To illustrate and assess the worth of this strategy, the Environmental Thresholds Values Model ('ETV-model') was developed following these criteria and applied to evaluate alternative plans for a transit corridor in the city of Granada, Spain. This Spanish case is very illustrative of the described problems.The development of ETV-Model and its application to MAG permitted to test the proactive dimension of the EA process with respect to: i) interaction level between EA-makers and transport planners; ii) the Abstraction level of the EA process with respect to traditional EA instruments; iii) the Role of the EA in urban transport planning;The reduction of abstraction level from the evaluation was a highlighted aspect to foster a more holistic dimension during the process. This meant to develop an integrated conceptual framework between the EA-makers and transport planners. The identification of 'mobility environments' in the first stage of the 'ETV-model' was very significant in this respect. Under these geographical units, the involved practitioners not only established the first criteria for the evaluation, but prescriptions on the final design of alternatives were emitted by EA-makers taking into account these spatial references. The estimation of an aggregated environmental performance value was considered by transport planners as an excellent way to obtain comprehensive conclusions, as well as, the adoption of reference values facilitated the understanding of specific environmental problems of alternatives between the two focus groups.Another highlighted aspect during the application of the 'ETV-Model' was the fact that the evaluation had a central role not only during the selection of alternatives, but also to modify the alternative selected in the last phase of the evaluation process. Since the earliest, the outcomes of the model reflected in general that Alternative S.1 had less environmental negative impact than Alternative S.0, although this statement was dependent on the 'mobility environment' considered. During the application of the ETV-model the outcomes were related to dynamics characteristics of urban transportation, covering different temporal periods and including the interaction between EA-makers and transport planners in different workshops/meetings. After analysing the two possible alternatives the decision module of ETV-model through the indicators 'Absorption capacity' and 'Improvement capacity' assessed possible changes to optimize the alternative selected (alternative S.1). The outcomes obtained oriented transport planners to modify the alternative with respect to the number of lines of public transport in the case of 'motorized traffic environment' and 'local and circulation environment', as well as, the walkable areas in the case of 'Local oriented environment'.
ResumenLa evaluación ambiental aplicada a la movilidad urbana evoluciona en los últimos tiempos propiciando nuevos enfoques y modelos conceptuales motivados principalmente por la necesidad de obtener resultados más válidos para orientar y gestionar las decisiones sobre la movilidad urbana.En este contexto de innovación metodológica se sitúa este artículo que considera la movilidad urbana como un ámbito de conocimiento, proyecto y planificación que resulta específico por el carácter complejo de sus impactos y la demanda de un enfoque integrado al evaluar su calidad ambiental. Las limitaciones de los enfoques, más o menos, convencionales de la evaluación ambiental, son identificadas para el caso de los proyectos de movilidad urbana, señalando fundamentos alternativos adecuados para generar modelos de evaluación proactiva. En este sentido, resulta esencial progresar de una visión constreñida basada en el impacto ambiental a otra más compleja basada en el rendimiento ambiental.En consecuencia, el artículo plantea las dimensiones relevantes para la evaluación ambiental proactiva de la movilidad urbana, para lo que es necesario basarse en indicadores de rendimiento ambiental que articulen un modelo de umbrales ambientales que facilite el enfoque integrado sobre diversos entornos de movilidad. Rendimiento, umbrales, entornos de movilidad y evaluación proactiva son integrados en un ejemplo de aplicación a un corredor urbano en el que se implanta un nuevo modo de transporte público (área metropolitana de Granada, España), diagnosticando opciones de gestión de la calidad ambiental de los diversos entornos de movilidad urbana articulados por el corredor en cuestión.
