Environmental Sustainability in Transportation Infrastructure

Airports urgently need resilient and affordable solutions to address stormwater quantity and quality issues and to promote the triple bottom line of sustainability. Recent years have seen increasing use of green stormwater infrastructure (GSI) strategies at airports. GSI solutions (e.g., bioretention systems, rain gardens, vegetated filter strips, permeable asphalt or concrete pavement, drainage wells, and amended topsoil) are designed to supplement or replace conventional grey infrastructure (e.g., impermeable pavements and curbs, inlets and pipes) that inhibit water filtration or infiltration and related natural treatment and flow attenuation processes. This work aims to provide a brief overview of the GSI strategies for airports, followed by a discussion of challenges and opportunities in balancing airport priorities in environmental, economic, and social values and operational constraints. The airport challenges in implementing GSI strategies mainly include those related to wildlife attraction, climate change, anti-icing/deicing compounds, and land use limitations. This work presents a synthesis of information that can be valuable in assisting airport decision-makers and professionals responsible for managing the stormwater programs and for the planning and project development of conventional grey infrastructure and new green infrastructure related to stormwater management.

Geophysical investigation of Elekuro and environs, Abeokuta, South western Nigeria was undertaken to explore the potential for further ground water development, considering the depth, thickness, resistivity and layer at which water can be obtained. The geo-electrical method used in the survey is Vertical Electrical Sounding. Six Vertical Electrical Soundings (VES) were conducted using the Schlumberger configuration covering the entire area. The VES data were subjected to an iteration software (WIN RESIST) which showed that the area is composed of top soil, weathered layer, fractured layer and basement. The result of a quantitative interpretation of the VES data obtained in a geophysical survey are represented by a geoelectric section which shows the sequence and relationship between the subsurface lithologies. The weathered layer and the fractured zone have been identified as the aquiferous in the area. The weathered layer is thicker in VES 1 and thinnest in VES 2, while the fracture basement is thickest in VES 1. Based on low resistivity values, overburden thickness and Reflection coefficient, VES1 has the highest and brightest potential for future groundwater exploration and development in addition to the existing ones.The study area falls within the basement complex of Southwestern Nigeria. The rocks are Precambrian in age as they lie between the pan African orogenic belts.

Rainfall and wet pavement have significant impacts on road safety. Wet percent time was found to be an important variable in wet pavement accident analysis. However, the accuracy of wet percent time can be impaired by data with quality issues, which have negative impacts on the identification of high wet collision locations. Hence, data quality control is a necessary and essential part of any weather station network used for generating wet percent time. The absence of quality control can result in poor quality data that severely limits their usefulness. This study showcased the first application of a methodology for the multi-step quality control of precipitation data. The methodology includes data preprocessing, various quality checks, and treatment of missing data. Historical hourly precipitation data reported by rain gauges were obtained from five network data sources to demonstrate this methodology. These five network sources provided data from over 2,000 weather stations in California. The results of quality control were employed by the California Department of Transportation to update its wet percent time information. The methodology can be adopted by other states conducting similar studies or for applications such as climate change research.

There are numerous linear best management practices used by many state departments of transportation (DOTs) for highway runoff treatment. An example of one type is a media filter drain (MFD) which is a trench filled with aggregate and three active ingredients: dolomite, gypsum, and perlite (MFDs are also called Ecology embankments or bioslopes). Initial research on MFDs predicted that their life spans were at least10 years. Recent studies indicate that for dissolved zinc and copper metal removal, the life span may exceed 20 years. The dissolved concentrations of these metals are of issue as higher concentrations in receiving waters can impact many aquatic species, particularly some cold water fish such as salmon. This study extended the life further in laboratory tests for MFDs made with media with slightly higher amounts of active ingredients. Zinc and copper removal remained high. However, some possible channeling was suspected with slightly lower removal rates after long periods without moisture.

Tack coats are a vital component of an asphalt pavement’s structural system because they bond the multiple asphalt lifts into one monolithic layer. Poor tack coat application results in poor layer bonding. The usual pavement distresses associated with inferior bonding are slippage cracks and shoving along with delamination of the surface lift. Often poor tack coat also contributes to more classic structural pavement distresses, namely fatigue cracking and potholes. Researchers have indicated that even with a loss of only 10% of bond strength, fatigue life can be reduced by as much as 50%. Moreover, the cost to an agency in the event of a bonding failure can potentially exceed the original costs of a maintenance overlay. Despite these facts, little attention is often paid to tack coat operations by both contractors and agencies, and pavement performance suffers.

Many metallic components in highway maintenance equipment fleet are at risk of corrosion, which is exacerbated in service environments where roadway deicers have been applied. Roadway deicers generally feature chloride salt(s) as their freezing point depressant. As such, the exposure to roadway deicers poses a substantial risk to highway maintenance equipment. This work will review best practices available to manage the risk of deicer corrosion to equipment assets and present a user’s manual for the use of maintenance agencies in the northern climate. The manual has addressed the following subjects: Corrosion Basics; Causes and Effects of Corrosion; Materials Used for Snow and Ice Control; New Equipment Specification; Repair, Rehabilitation and Retrofitting of Existing Equipment; Preventive Maintenance Practices; Training and Facility Management. This manual would be applicable to the winter maintenance community and could aid agencies in the prevention of metallic corrosion and the extension of service life and reliability/readiness of equipment assets.

Crack repairing is considered a cost-effective technique in preventive maintenance, provided that right repairing method and material are selected and properly applied. By means of timely and effective crack repairing manners, the service life of pavement could be increased and leads to significant cost savings for the highway management system. In this study, a chemical grouting method that usually used in the repair of cement concrete structures was employed and modified for the crack repairing of asphalt concrete pavements. In order to evaluate the feasibility and effectiveness of the proposed method, in-situ experiments were performed on several typical pavement sections with all kinds of cracks. Through long-term observation and by comparison with the conventional crack repairing method, the chemical grouting method was proved effective for the crack repairing of asphalt pavements, and exhibited desirable durability under heavy traffic loads.

Cracks significantly deteriorate the in-situ performance of concrete members and structures. Electrochemical deposition tests were performed to repair different types of damaged concrete specimens, such as specimen with the load-induced cracks and with the internal defects. Based on the authors’ previous work, electrochemical deposition tests are performed with the porous concrete specimens to assess its healing effects. Three kinds of experiments have been utilized to evaluate the deposition healing effectiveness. The experimental results show that the flexural strength improves after healing. The average ultrasonic pulse velocities increase from 3,546 m/s before healing, to 3,617 m/s after 14-day healing, to 3,656 m/s after 35-day healing, meanwhile the average porosities reduce from 0.2999, to 0.26245, and finally to 0.24092.

Thermal cracking is a natural feature of most of Alaska’s asphalt concrete (AC) pavements that influences long term maintenance costs and drivers’ perception of road performance. Major transverse thermal cracks penetrate through not only the pavement layer itself but usually extend several feet into the aggregate materials below. A significant portion of Department of Transportation (DOT) Maintenance and Operations budget has been allocated to crack sealing and associated work. However, Alaska researchers are beginning to understand that the inevitable thermal cracking can be significantly controlled by making simple changes to new road designs. Past research in Alaska and elsewhere found that thermal cracks can be controlled if properly spaced saw cuts are made in the pavement surfaces of newly built pavement structures. Research presented in this paper looks at the different case of whether precutting can influence thermal cracking when only the top few inches of an old, thermal cracked, pavement structure have been reconditioned and repaved. Two years of monitoring show that precutting exerts significant control on thermal cracking of the new pavement surface even if most of the previously-cracked underlying aggregate pavement structure was left in place. However, precutting is most effective when the saw cuts are made at or very near the locations of the old thermal cracks.

In recent years, North American highway agencies have increasingly adopted innovative snow and ice control strategies, including anti-icing and pre-wetting practices. In 2005, to synthesize the benefits and challenges of implementing such strategies, a national survey was conducted. However, insufficient information and limited understanding were found to account for their low usage at that time. A decade later, research is needed to document improved user experience and scientific understanding on these strategies, which can be used in a comparative manner. Through a follow-up survey launched in April 2014 with the same focus as the 2005 survey, a contrastive synthesis is presented which summarizes changes in the evolution of anti-icing and pre-wetting over the past decade, including the implementation of these snow and ice control strategies, related costs, environmental concerns, corrosion, and community response. The research demonstrates the elevated and indispensable status of anti-icing and pre-wetting strategies in current winter roadway maintenance activities, compared with their limited use ten years ago. The research further supports their positive effects on economic, environmental and social goals, which is attributable to the proactive nature and environmentally responsible performance of anti-icing and pre-wetting. Finally, gaps in current operations and the need for further research are discussed.

It has long been suggested that a much more economical and sustainable approach be developed to address crack sealing effectiveness in Alaska. The development of a new method named special thermal crack evaluation (STCE) in a previous study served to directly and efficiently guide the crack sealing practices as opposed to the other nationally-used pavement surveying methods, including Long Term Pavement Performance (LTPP) and Pavement Surface and Evaluation Ratings (PASER) . However, no or little research has been found to compare and correlate STCE with the other two methods. This paper presents a study to fulfill this research need. Further data interpretation showed that STCE was capable of guiding the decision-making on crack sealing practices, while the other two methods provided quantitative measurements and general rating of the sealed or non-sealed cracks. In addition, the correlation between STCE and the other two methods recommended that STCE better be used along with the other two methods for a better and more complete guidance on current or potential crack sealing practices.

This project aims to identify sustainable construction techniques appropriate for remote and cold regions, noting extension to operations and maintenance as applicable. This paper explains the methods used to review the vast body of literature regarding green construction in warm regions, and the use of a hierarchal taxonomy to categorize the information found in order to reduce it to a form useful for eventual presentation to engineering and construction managers.

There is a need for the identification of environmental best management practices (BMPs) to aid in responsible and cost-effective operation of winter maintenance programs. State Departments of Transportation (DOTs) are continually challenged to provide a high level of service on winter roadways and improve safety and mobility in a cost-effective manner, while at the same time minimizing adverse effects to the environment, vehicles, and transportation infrastructure. Understanding and minimizing the negative impacts of deicers is critical to effective and responsible winter maintenance operations. Increasing contamination from the continued use of snow and ice control products has become a significant environmental concern that has detrimental effects on air, water, soil, vegetation, humans, and wildlife. Snow and ice control BMPs have been developed in all aspects of winter maintenance operations. This paper will focus on snow and ice control BMPs with the greatest potential to decrease the environmental impacts of winter maintenance operations including proper material storage and handling, applying the right amount of material in the right place at the right time, and facility management and post storm clean-up. By utilizing the identified best practices, an organization can realize cost and material saving, reduced person and vehicle hours and emissions, and realize a reduction in the impacts of snow and ice control operations on the environment.

This paper presents the experimental study of a snow melting system embedded in concrete sidewalks/slabs at Northern Arizona University (NAU) as a practice of deicing technology. NAU is located in Flagstaff, Arizona. In the winter months with high attitude (7000 feet/2,250 meters), temperatures in Flagstaff are extremely cold and the amount of snowfall (approximately 108 inches/2.74 meters per year) has been significant. As of 2012 NAU has planned to install snow melting systems in sidewalks with the goal to provide visitors, students, faculty, and staff with a stably safe environment for transportation in the snow. Hydronic heating system has been selected to generate heat energy using glycol-water as the heat source. Pipes are embedded 4 ½” (11.5 cm) below the pavement surface with glycol-water being circulated within the pavement. To help with mechanical system design, numerical modeling along with yearly heat output values in Flagstaff were calculated. In January 28, 2013, a snow storm was blasting across the city. The snow melting systems were turned on at midnight to heat the concrete slabs. Based on an observation in the early morning of the following day at 7am, no snow accumulation was found on all heated sidewalks at the three project locations. The observation has validated our heat output computation and numerical analysis, and has proved they were appropriate. The hydronic system embedded in the pavement was working very well to generate heat energy to keep the snow away from the sidewalk surfaces. To date, the snow melting systems installed at NAU have successfully demonstrated their abilities to heat the pavements and keep the snow from the surface.

Shining above, the sun has always been an obvious source of energy and recently it has been used on roadways also to produce electricity. The “Raised pavement markers” (RPMs) have been in use in Oregon for many years. A study by Oregon Department of Transportation (ODOT) in 2004 suggested that the solar powered RPMs can be used on the roadway pavements satisfactorily. This study included laboratory testing and field observations. Light Emitting Diodes (LED) is fixed inside the Solar Raised Pavement Markers (SRPM). They can be used along the sidewalk pathways. Photovoltaic (PV) cells work by using semi-conductors to absorb light and create a flow of electrons. The advantages of using the solar powered roadways are not immediately felt right after the construction. The solar photovoltaic panels can be placed on the sound barrier walls and on bridge structures also. This paper deals with the current status of technology related to the solar panels that are used on roadways, bicycle paths, pedestrian sidewalks and along roadside. This paper also discusses the pros and cons and the feasibility of using the solar energy from the roadway pavements, parking lots, sidewalks, bicycle paths and roadside.

Environmental considerations can be an important part of some decision-making procedures, along with other factors such as cost and risk, when weighing multiple alternative product or process choices. Availability of environmental data is crucial for environmental assessments. In marine vessels, lubricating oil use can vary widely between ships with different filtration systems, engine parameters, and oil change scheduling procedures, all of which can be altered to change lube oil usage. This research addresses a need for environmental data for mineral lubricating oil, in the format of a life cycle assessment (LCA) data synthesis based on a case study for the Washington State Ferries. Data are collected and presented separately for engine oil acquisition, use, and disposal, utilizing cross-platform data sourcing including currently existing literature, ferry oil analysis results with simple combustion modeling, and a software tool database. The purpose of this data assembly is to provide decision-makers with a simple source for the impacts of a typical volume of oil throughout its life cycle. The functional unit used is 3.79 liters (one gallon) of oil, which allows for adjustments for oil use by different systems for equivalent functional comparisons between alternatives, lending widespread applicability.

This study uses the Pavement Life-cycle Assessment Tool for Environmental and Economic Effects (PaLATE) to study the benefits of energy savings and carbon emission reduction derived from using Reclaimed Asphalt Pavement (RAP). According to the findings, producing RAP mixture with 30% of reclaimed asphalt materials results in 16% of energy saving and 20% of carbon emission reduction while compared to that of producing the same amount of virgin hot mix asphalt mixture. The mitigation of energy consumption and carbon emission is mainly due to the saving on virgin asphalt binder. However, it is found from a life cycle approach, only if RAP pavement gives a service life at least 80% of that of virgin materials, using RAP becomes a feasible way to make the pavement greener.

One way to assess the life-cycle performance of bridge decks is to use risk rating factors. Risk rating factors tend to increase with time, as a bridge deck ages and deteriorates. The major influential factors of bridge deck deterioration in cold climates include materials characteristics, construction quality, freeze/thaw cycles, deicer exposure, and overload trucks. Unlike laboratory testing where all test samples are subjected to similar environmental conditions, the concrete samples cored from bridge decks experienced much more complicated conditions. As such, it is a challenge to evaluate the field conditions of concrete structures, pavements and bridge decks through the analysis of their core samples. An assessment tool to facilitate the condition assessment of concrete bridge deck using a limited number of core samples is useful for bridge owners to implement preservation, repair and rehabilitation strategies in a timely fashion. In this study, the maintenance history and gas permeability and strength testing results from limited core samples were analyzed using a simplistic empirical-mechanistic model. The model was developed to assess the current condition of bridge decks exposed to deicer environments. This was made possible by coupling the percolation theory with the power law for strength and permeability. Specifically, the model accommodated input parameters of freeze/thaw cycles, average daily traffic (ADT), average annual deicer usage, and engineering properties measured from deck core samples (e.g., splitting tensile strength and gas permeability coefficient). Microscopic characterization through scanning electron microscopy (SEM) confirmed the validity of the new tool, as it better captured internal damage in concrete decks that showed little signs of surface distress.

The engine of any economy is good transportation infrastructure and the supply of energy to support the freight transport and traveling public. Transportation infrastructure network assets have been the backbone of passenger mobility, vital for freight transport, and an important contributor to the nation’s economy. Transportation infrastructure systems in a “sustainable” world require engineers to minimize demand on natural resources, energy consumption, and adverse impacts on the environment. This paper presents key results of a case study of technical feasibility and economic viability of an alternative transportation corridor on the Gulf Coast of Mississippi. The results of the life cycle costs and benefits favor a commuter rail service on a shared rail corridor. Added benefits include reduction of auto traffic and auto emissions. Additionally, this paper discusses the feasibility of utilizing piezoelectric materials in the harvesting of lost energy from the vibrations produced by train-rail corridors. The use of the piezoelectric sensor is a well-established technology for counting traffic on roads. In recent years, piezoelectric material has emerged as one of the most promising methods for energy harvesting from traffic-induced vibrations. This paper presents a second case study that investigates the enhancement of the piezoelectric material by coating it with a special nano particle mixture. The results indicate a more than 400% improvement in energy harvesting compared to the traditional piezoelectric material. This provides a great opportunity to tap into this source of energy being lost to the environment in the form of vibrations from train-rail corridor systems.

In the United States, the Federal Bridge Formula (FBF) has been used to set the Gross Vehicle Weight (GVW) limit and axle weight limit for various vehicle configurations. Further, the American Association of State Highway and Transportation Officials (AASHTO) developed a set of legal loads that closely match the FBF in the short, medium, and long truck length ranges and are used to evaluate the need for bridge weight limit posting. Specialized Hauling Vehicles (SHVs) were developed in recent years and they play an important role in the trucking industry. Typically, SHVs refer to single unit (SU) vehicles with closely spaced multiple axles that can carry up to 80,000 pounds. Even though SHVs meet the requirement under FBF, these newer axle configurations were not considered in the original development of the FBF and AASHTO legal loads. As such, FBF does not adequately restrict SHVs and most likely overstress the bridges. This study was conducted to examine the current knowledge related to the impact of SHVs on highway infrastructures, economy, and safety. The key findings from the study include: (1) Relative to conventional trucks, SHVs may not induce significant damage to asphalt pavements and can potentially induce additional damage to concrete pavements; (2) Relative to conventional trucks, SHVs can induce significant damage to short span bridges particularly to short span timber and steel bridges; (3) Bridge weight limit posting is expected to increase with the allowance of SHVs; and (4) SHVs are likely to benefit economy and safety. Findings of the study will contribute to environmentally sustainable highway infrastructure in the presence of SHVs.

With the growing reliance on chloride-based deicers in winter roadway maintenance operations, the concerns over their adverse impacts have been highlighted in recent years, especially the direct stress that applied chemicals bring to the receiving roadside soil, water bodies, aquatic biota, and vegetation through snowmelt runoff, infiltration and wind blow. This work started from synthesizing current knowledge on the negative/toxicological effect of chloride-based snow and ice control products to the natural ecosystem, and then put an emphasis on the examination of typical methods used to assess the toxicity of chloride-based deicers on the water quality and aquatic biota in the laboratory and field tests. The summary focused on the species to test, calculation process, and influential factors in the laboratory test, followed by the field sample collection options, timing of sampling, key variables and bio-assessments in the field test to quantify toxicological effects of chloride-based chemicals. Finally, efforts on current theoretical research and the need for further work (e.g., field monitoring and bio-assessments or bio-monitoring over time, the effective correlation between laboratory toxicity data with field data, and the relationship among key variables and resulting toxicity index) were discussed.

Traditionally, the main priority of winter road maintenance has been assigned to level of service, cost-effectiveness, and corrosion rather than other less well-characterized effects such as impacts to water quality. It is increasingly vital to understand the environmental footprint of deicers, including their impacts on aquatic ecosystems. Chloride based deicers do not degrade in the natural environment and their application on winter pavements can lead to accumulation in adjacent environments over time. Information presented to date on deicers generally includes chemical composition and performance of deicers, while additional information on deicer aquatic toxicity is needed to enable fully-informed decisions by stakeholders. This work presents a state-of-the-knowledge review of the impacts of chloride based deicers and additives on water and aquatic species, and the issue of heavy metal leaching. Toxicity associated with the direct effect of deicers or with the indirect effect via their interactions with runoff chemistry is reviewed as well. This work will assist the stakeholder agencies in the search for effective practices to reduce the toxicity and other water quality implications of chloride based deicers.