The South Carolina Department of Transportation noted that 1,700 of its employees picked up 13,130 bags of roadside trash weighing 209,725 pounds on November 17 in support of Lt. Gov. Pamela Evette’s “Grab A Bag SC 2020” statewide cleanup program.
[Photo courtesy of the South Carolina Department of Transportation.]
“We ask the public to help us keep the newly cleaned highways litter-free,” noted Christy Hall, SCDOT’s secretary in a statement. “Not only is litter an eyesore, but it can clog drains, pollute waterways, and hurt our state’s economy by discouraging economic development.”
The agency added that SCDOT employees are planning to participate in another statewide litter cleanup day in spring 2021.
SCDOT’s Keith Bowman and Peter McKnight picking up litter during the agency’s “Fall Cleanup.” Photo by SCDOT.
SCDOT’s litter cleanup effort mirrors similar efforts conducted nationwide in 2020 by state departments of transportation.
For example, the Georgia Department of Transportation launched an anti-litter campaign in October called “Keep It Clean Georgia” that seeks to prevent and eliminate litter along 50,000 miles of interstates and state routes that crisscross Georgia.
That followed the Virginia Department of Transportation’s recent Virginia is for Lovers, Not Litter public outreach campaign, kicked off in September, that aims to raise awareness about Virginia’s roadway litter problem. The agency noted it spends nearly $3.5 million annually to remove litter from Virginia’s roadways, with more than half of that litter coming from motorists with another 25 percent from pedestrians.
Then there is the Alabama Department of Transportation, which launched an anti-litter campaign entitled “Trash Costs Cash” in August. The campaign uses television, radio stations, and social media sites such as Facebook and YouTube to highlight a major increase in litter fines and penalties authorized by the state legislature in 2019. The agency – which spent almost $7 million in 2019 to clean up litter along state roadways – noted that fines for littering have doubled statewide. The minimum fine is now $500, up from $250 for a first conviction, while the second conviction is $1,000 and up to 100 hours of community service.
In the latest episode of the Environmental Technical Assistance Program or ETAP Podcast, Carlos Swonke – environmental affairs division director for the Texas Department of Transportation – explained how his agency implements environmental Justice or “EJ” strategies within its transportation project work.
[Photo courtesy of the Texas Department of Transportation.]
According to the U.S. Department of Transportation, “EJ” refers to the process by which both the fair treatment and meaningful involvement of all people – regardless of race, ethnicity, income, national origin, or educational level – is integrated into the development, implementation, and enforcement of environmental laws, regulations, and policies.
Texas DOT’s Swonke noted during the 25-minute podcast that the National Environmental Protection Act or NEPA plays an important role in the EJ process.
“NEPA talks about addressing the natural and human environment,” he said. “More recently, in the last 10 to 15 years, we’ve looked harder at the social and economic impacts of transportation projects, especially on urban streets. NEPA is the umbrella law that puts us in the position of looking at those issues and conducting analysis to look at impacts on communities – especially minority and low-income populations.”
Swonke offered up an example of how EJ works within transportation project planning by highlighting the $7 billion North Highway Improvement Project, which seeks to reconfigure four interstates in and around the city of Houston.
“We’ve been working on this project for almost 10 years now and it will result in 160 single-family home relocations, 463 apartment unit relocations, 486 low income, and public housing relocations, and 344 businesses being displaced,” he said. “Along with public meetings to hear directly from affected communities, we engaged in technical analysis using 2010 census data and on-the-ground work to identify populations and neighborhoods considered to be EJ neighborhoods—information we just published in the final report on this project.” To listen to this podcast, click here.
State departments of transportation across of the country are looking at new and better ways to predict traffic noise levels, as well new materials for highway sound barriers, in order to reduce the overall cost of noise abatement efforts.
[Photo courtesy of the Missouri Department of Transportation.
This second of a two-part series on state DOT noise abatement strategies examines some of the research state DOTs are conducting to find more cost-effective and innovative designs and materials to mitigate the high levels of roadway noise: everything from using less expensive materials or smaller barriers to designing duel use barriers such as vegetation walls and solar panels.
Traditionally, sound wall barriers are pre-cast or cast-in-place concrete sections. However, several different types of materials have been in use since the beginning of sound barrier construction in the 1960s. The latest noise barrier inventory – maintained by the Federal Highway Administration –indicates barriers constructed with a single material make up 84% percent of all noise barriers. Furthermore:
Concrete comprises 55 percent of those barriers.
Block represents 18 percent of those barriers.
Wood comprises 5 percent of those barriers.
Metal, berm, and brick together account for another 5 percent of single material barriers.
“Other” materials comprise the final 1 percent of those barriers, including acrylic, composite, fiberglass, glass, opaque plastic, and transparent plastic.
There are noise walls designed with absorptive material to absorb sound, but the majority are built to deflect sound. Barrier analysis and design must meet the requirements of federal regulation 23 CFR 772 for all federally funded projects.
The Ohio Department of Transportation is in the start-up phase of a research project expected to begin January 2021 to look at the effectiveness of vinyl fence as a noise barrier as opposed to the now-standard concrete barriers. The project involves constructing two 8-foot tall vinyl fences at two different locations, testing them for noise reductions, and comparing the reductions to nearby concrete noise walls.
Graphic courtesy of the California Department of Transportation
The Ohio DOT plans to use readily available vinyl fence materials that already have specifications available – indeed, one type of fence earmarked for testing is available at the local Home Depot.
Noel Alcala, the noise and air quality coordinator at the Ohio Department of Transportation and noise workgroup coordinator on behalf of the American Association of State Highway and Transportation Officials, explained in an interview that while vinyl is a lot less durable overall than concrete, it is “a lot less expensive and we have an indication that the noise reduction will be very noticeable.”
The Ohio DOT is also studying the feasibility of using vegetation growing on noise walls as both a sound absorber and an air quality improvement and plans to complete a report on that effort by the end of 2020. That effort – based on research conducted in 2010 – looked at a 400-foot long section of “green noise wall.” That wall consisted of a 12-foot-high section of stacked, 70-pound bags sprouting plants and grass as a way to muffle highway sound.
Trees and shrubs can decrease highway-traffic noise levels if high enough, wide enough, and dense enough, but it would take at least 100 feet of dense vegetation to provide the same benefit as the smallest feasible noise wall. Because of this, the FHWA has not approved using vegetation for noise abatement.
However, future studies could show more innovative choices will result in higher levels of noise absorption. For instance, environmentally friendly and sustainable bamboo growth may provide the needed noise level abatement to meet FHWA requirements. One feasibility study presented at the 2016 International Congress and Exposition on Noise Control Engineering indicated that the noise-reducing effect of a bamboo barrier with a height of 5 meters (roughly 16 feet) and a thickness of 6 meters (nearly 20-feet) is roughly comparable to a 3-meter (nearly 10-foot) high solid noise wall.
That study found that sound barriers equipped with solar panels are used successfully in Europe, though there are no current in-place solar panel noise barriers in the United States. However, two states, Massachusetts and Georgia, are currently working with partners to pursue pilot studies using solar panels built into sound walls so they can produce renewable energy without compromising their abilities to reduce noise – and do so safely. Given the number of miles of sound barrier currently constructed in the United States – over 3,000 miles total – the study found the potential for energy production could be at least 400 Gigawatt hours annually, roughly equivalent to the annual electricity use of 37,000 homes.
The California Department of Transportation is also looking at innovative designs to save money on noise abatement construction.
Currently, Caltrans is exploring the feasibility and effectiveness of lower height barriers and berms. Its latest research suggests that at freeway speed, most all light-vehicle noise is at the tire/pavement interface — literally at the zero-foot level. Meanwhile, on most heavy trucks — even with tall exhaust stacks – most noise is below 3.3-foot level.
That means shorter less-expensive noise barriers would help attenuate noise. A low vehicle noise source also means a short (4-foot) solid-concrete safety-barrier could provide noticeable noise mitigation if positioned correctly in the road cross-section. Shorter barriers mean lower overall costs. State transportation agencies across the United States are making strides to protect the public from high levels of traffic noise. Click here for a list of current state DOT noise reduction projects.
Although Florida trails other big states in government support for electric vehicle infrastructure, the Florida Department of Transportation is now taking a lead role in building out an EV recharging network, according to a new report.
[Photo courtesy of the Florida Governor’s Office.]
The Southern Alliance for Clean Energy and Atlas Public Policy recently published “Transportation Electrification in Florida,” a brief that makes the case that Florida’s government has not kept pace with its own citizens in transitioning to EV transportation. Floridians purchase 4 percent of all EVs in the country, but Florida’s government only spent $23.3 million on EV infrastructure, representing about 1 percent of all states’ spending, according to the report.
This has put Florida is in a “really unique situation” because it is second in the country in EV sales and number of chargers, but only 18th in per-capita sales and 30th in per capita chargers, according to Stan Cross, Electric Transportation Policy Director for SACE.
“What that means is that Florida runs the risk in getting behind in charging really quickly,” Cross said. “If numbers [of EV buyers] go up quickly, Florida can’t keep up.”
However, the Florida DOT is not only playing catch up, it is working to get ahead of the curve with a stated goal to “position Florida as a national leader in EV adoption and infrastructure,” according to a presentation to other agencies and stakeholders.
As a result, the agency is developing an EV charging infrastructure master plan for the state and preparing legislative initiatives to encourage even more EV usage. These actions were the result of the new Florida Essential Infrastructure Law that puts the Florida DOT and other state agencies in the EV business.
Right now, the agency is modeling location criteria for EV charging sites, formulating an implementation strategy, and forecasting future EV usage and its impact to the state’s Transportation Trust Fund – largely fueled by gasoline and diesel taxes. Florida DOT’s effort is comprehensive, including support of EV transit and school bus fleets and integration with hurricane and disaster evacuation plans.
“The [Florida] DOT is thinking through what some of the policy implications are for moving the needle, the principles that should drive the state’s thinking on this,” Cross said. “[They] have a lot to figure out, and they’ve put many of the right policy recommendations on the table.”
In a recent blog, Cross noted that many of the policies the Florida DOT is studying “are aligned with policy considerations being implemented successfully” in other states, including promoting EV usage throughout the state, supporting rural infrastructure development and study incentives to potential EV buyers and to utility companies to help build charging stations. Most of Florida DOT’s work is in the planning stages as it prepares to issue a status report with preliminary recommendations to the governor by December 1.
State departments of transportation across of the country are looking at new and better ways to predict traffic noise levels, as well new materials for highway sound barriers, in order to reduce the overall cost of noise abatement efforts.
[Photo courtesy of the Ohio Department of Transportation.]
The first article of this two-part series will examine some of the new tools state DOTs are developing to better gauge the impact of noise on communities near transportation infrastructure such as highways.
First, some background: According to the noise barrier inventory maintained by the Federal Highway Administration, more than 3,000 linear miles of noise wall barriers have been built since the 1970s across the United States.
Such sound barriers remain an essential part of highway design and construction as the World Health Organization determined that prolonged exposure to high levels of noise “interferes with people’s daily activities … disturbs sleep, causes cardiovascular and psychophysiological effects, reduces performance and provokes annoyance responses and changes in social behavior.”
Photo courtesy of the Iowa Department of Transportation
The Noise Pollution and Abatement Act of 1972 requires state departments of transportation to monitor and manage highway traffic noise generated by federally funded projects on existing and planned roadways. When that sound exceeds certain thresholds, 23 CFR 772 specifies mitigation efforts must be undertaken to reduce highway traffic noise.
Yet the cost of meeting those regulations and protecting the public against the roar of the vehicles — the predominant sound for both cars and trucks is that of tire-pavement interaction – takes considerable funding.
For example, between 2014 and 2016, FHWA found that total construction costs for noise barriers topped $671 million in just a three-year period – an average of $2 million per mile of noise wall.
That’s why many state DOTs are trying to find ways to reduce the cost of noise abatement efforts, noted Noel Alcala.
“The main goal of more accurate noise abatement modeling can result in cost reduction,” explained Alcala, the noise and air quality coordinator at the Ohio Department of Transportation and noise work group coordinator on behalf of the American Association of State Highway and Transportation Officials, in an interview. “Modeling noise levels more accurately can likely reduce costs noise wall in construction.”
States currently use the FHWA Traffic Noise Model 2.5 to predict noise levels that will occur once a road is built or expanded – even if that expansion occurs several decades in the future.
That complex formula includes the mixture of cars and trucks expected on the road; the buildings and vegetation in the area that would block some sound; the configuration and ground quality of the land between the road and the homes; the ways the sound is expected to diffract around the wall; and other key factors. Other weather factors can also play a role, such as wind direction and ground and air temperatures. Also considered is the height where the noise is actually originating – at roadway level or top of truck stacks.
Courtesy of Caltrans
The overall goal of some states, such as California – which sports over 750 miles of highway sound walls – is lowering the noise level at the transportation infrastructure source – a far-cheaper effort than blocking the noise with a more expensive sound wall.
To that end, the California Department of Transportation has worked over the last few years to implement the most recent National Cooperative Highway Research Program or NCHRP findings into newer modeling techniques.
Caltrans relied on documents such as NCHRP Report 635: Acoustic Beamforming: Mapping Sources of Truck Noise, which experimentally validated a practical acoustic “beamforming” measurement technique.
“Beamforming” uses a type of camera that takes pictures (or video) of soundwaves and illustrates that very little acoustic energy comes from tall truck exhaust stacks. Meanwhile, it shows that most highway noise is tire/pavement related and usually occurs very close to the pavement.
NCHRP Project 1-44, reported in NCHRP Report 630, also proved valuable to Caltrans efforts as it proposing a test method for measuring tire-pavement noise at the source using the on-board sound intensity (OBSI) method.
The agency also is implementing AASHTO T 360-16 (2020) – the Standard Method of Test for Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity (OBSI) Method – to reevaluate noise modeling efforts and improve modeling to provide more accurate results. Caltrans has also moved to use more precise noise measurement processes, which it believes will lead to lower community noise levels.
“The AASHTO Standard which precisely measures pavement acoustics, allowed a lot of this work to be accomplished, explained Bruce Rymer, senior engineer in the Hazardous Waste, Air, Noise, & Paleontology Office within Caltrans.
“Using this new measurement technology, we found pavement acoustics had a much larger influence on roadside noise levels than previously acknowledged,” he said, “This is important for state DOTs because noise impacts of transportation projects on roadside communities have to be quantified and analyzed in order to receive federal funding.”
Other states are looking at ways to more accurately predict the costs of sound mitigation as well – now and in the future.
Iowa, for example, is looking at developing a new noise wall cost GIS-based prediction tool that incorporates residential lot information while ensuring that projects requiring noise abatement are properly planned and funded.
Charles Bernhard, Iowa DOT’s Traffic Noise Engineer, said those new processes include five distinct efforts:
Mapping out five-year highway project plans.
Eliminating highway projects that do not have an annual average daily traffic or AADT of greater than 10,000.
Eliminating projects by “work type” that do not meet the definition of a Type I project for noise
Creating a “parcel layer” that includes all residential parcels within 200 feet of the “edge of pavement” of the remaining highway segments.
Visually evaluate each remaining highway segment to determine if the segment has a “cluster” of seven or more residential parcels within the 200-foot “buffer.”
Part 2 of this noise abatement series will examine some of the new types of sound wall materials some state DOTs are studying.
The Virginia Department of Transportation recently made a major historical discovery at an old Civil War fort uncovered in the median of Interstate 64 near Williamsburg: A “witch bottle.” The superstition surrounding this rare artifact dates back hundreds of years to 17th century England when such “counter magical devices” served as “protection” against witchcraft and evocation.
[Photo courtesy of the Virginia Department of Transportation.]
To determine the effectiveness of its erosion- and sediment-control techniques, the Iowa Department of Transportation recently teamed up with Iowa State University over two construction seasons to establish which ones worked the best and which ones needed improvement.
[Photo courtesy of Iowa Department of Transportation.]
According to an Iowa DOT blog post, Melissa Serio with the agency’s construction and materials group teamed up with Mike Perez, an Iowa State researcher, to examine alternative erosion and sediment control techniques and adaptations used successfully by other transportation agencies to see how well the Iowa DOT’s standard practices.
Some of Iowa DOT’s frequently used erosion and sediment control techniques include: fabric silt fences to slow water flow and collect sediment; porous mesh tubes (called wattles) filled with straw or other material to control storm water flow; sediment basins or small retention ponds to hold water until solid materials can settle; and rock check dams.
“While we were convinced these elements help control erosion and sediment, it wasn’t clear whether these were the most effective or whether there were other approaches that could be undertaken to achieve better or less expensive results,” Serio explained. “It was important to understand the feasibility of possible changes to practice and identify the right improvements that could be put in place at the right price.”
Photo courtesy of Iowa DOT
While some of Iowa’s existing techniques already performed well, several potential improvements became apparent over the course of the two-year study. For example, simple adjustments to silt fences included reducing the space between posts, adding wire support to the fence’s fabric backing, and cutting a notch, or weir, at the top of the fence so that overtopping of water could be directed to the most desired location.
Even as the research pointed to potential new best practices, the Iowa DOT said this study “also challenged our expectations.” For example, sediment basins appeared not to be as effective a sediment control measure as had been previously thought. In fact, some data collected suggested that water leaving the basins might have more sediment than it had when entering.
“Further research in a controlled environment will provide more insight, but these initial findings are extremely valuable as we seek to maximize the effectiveness of our erosion and sediment control measures,” the agency noted. “We plan to include the most effective and cost-efficient erosion and sediment control treatments identified in this research project as part of standard road plans in the near future – mostly likely beginning the spring of 2021,” the Iowa DOT said.
