Sustainability can be incorporated at all stages of life of road infrastructure—road planning, design, construction, maintenance and rehabilitation, and management and operation. By implementing these practices, steps are taken to lessen the detrimental effect of the transport sector on the environment.
Roads give rise to various environmental problems and it is crucial to address these impacts early in the road development process. The most effective way to do so is through Strategic Impact Assessment, which provides an early and pro-active consideration of the environmental constraints and opportunities to minimize the adverse and maximize the favorable effect on the environment. A Strategic Environmental Assessment is a preliminary process for reviewing and evaluating policies, plans and programs, as well as other draft proposals for large-scale projects and initiatives.
Case Study: A Strategic Environmental Assessment was done for the Norwich Area Transportation Strategy’s (NATS) Implementation Program (IP). NATS placed a high emphasis on growth and accessibility. The SEA complemented that objective, but made sure that the NATS IP will have a more positive environmental effect by giving direction to the project. This project resulted in an overall neutral effect on environment, as opposed to a detrimental one.
Successful development of projects depends highly on the design phase. To support the design process and maintain a clear, structured approach to project development, environmental design objectives that balance engineering, cost, safety, and environment need to be set.
Case Study: The 7.2km stretch of A470 between Dolwyddelan and Pont-yr-Afanc lies at the heart of an environmentally-sensitive area. A project to widen and upgrade that route corridor would have led to undesirable environmental impacts, such as loss of stone walls and mature trees, which would have led to habitat degradation for the bats, lizards, birds and mammals that live there. The design focused on fitting the road carefully into the landscape by only constructing what that essential for improving road safety and by limiting the impact on important outcrops, trees and streams. A habitat for bats was incorporated into the design to help fully integrate the road into the landscape.
There are several environmental issues that arise during the construction phase of road infrastructure, including energy consumption and greenhouse gas emissions, water consumption, and ecosystem disruption.
In order to mitigate energy consumption and greenhouse gas emissions, construction companies can use paving products produced at lower temperature and with less energy consumption, recycle to reduce the use of raw materials and minimizing waste, and use optimized production plants which should result in more efficient energy usage.
Water is used during compaction of granular pavement layers, to suppress dust and to regenerate vegetation. Rain-water harvesting and use of treated-water effluent from manufacturing processes in proximity are options to consider reducing the toll of heavy water usage.
To mitigate ecosystem disruption, construction practices that afford minimal disruption and quick rehabilitation to flora and fauna, as well as incorporating the construction into the habitat, should be adopted.
Case Study: Development of the Road Energy System in the Netherlands extracts heat from asphalt pavements in the summer, stores it in underground aquifers and uses the heat to warm buildings in the winter. There is an estimated annual reduction of 1,600 tons of CO2.
Maintenance and Rehabilitation
Even though construction contributes to the most detrimental environmental impacts within road infrastructure construction, maintenance presents a wide array of impacts as well. To mitigate risks, each maintenance area should develop an Environmental Management Plan that maps sensitive receiving environments, clarifies Standard Operating Procedures and clearly delineates roles and responsibilities in order to ensure environmental aspects are adequately managed.
Case Study: An alternative pavement method was used to in a pavement rehabilitation project at the Isle of Man Airport, in which cold in-situ recycling was used. This option delivered a sustainable solution with substantial reductions in cost (40%), energy consumption (44%) and carbon dioxide emissions (32%) when compared to the conventional design. By reducing the amount of raw material used and the amount of emissions released, this project minimizes the damage done to the environment.
Management and Operation
No matter how prudent one has been during the previous stages, it is during the operation that many parameters may change, leasing to the necessity of immediate and effective actions to reduce any relevant environmental impacts. Environmental protection during the operation stage of a road is a continuous process, requiring constant monitoring of various parameters and implementing direct or indirect measures that the environment and quality of life are not compromised. Environmental aspects that need to be monitored and protected include air quality, biodiversity and landscape, cultural heritage, water and soil, storm water, noise and waste.
Case Study: Michelin developed environmentally-friendly tires that enhance their fuel efficiency to reduce CO2 emissions, improve their longevity, and reduce to external noise. The 17 billion liters of fuel saved and 43 million tons of CO2 not released are attributed to Michelin green energy tires.
Case Study: The Environmental Management System in Egnatia Odos motorway organizes and implements environmental protection and mitigation measures in the design, construction, maintenance and operation stages of the project. This system protects flora and fauna and more than 80 settlements by monitoring noise, water and air quality.