Pavements Past and Future
When Henry Ford introduced the Model T to the public in 1908, transportation was forever changed. Automobiles ballooned in popularity and with that came the need for infrastructure capable of supporting them. The past 100 years have been transformative for highway construction and engineering, with the formation of the Transportation Research Board, the establishment of the Interstate Highway system, the engineering of unique roads, and the development of technologies that have streamlined transportation and improved safety.
Formation of the Transportation Research Board
The National Advisory Board on Highway Research (NABHR) was established in 1920 in New York City as a way of sharing information and research on highway engineering.
The first NABHR annual meeting was held in 1922 in New York City, which hosted 30 attendees and created its first six technical committees. Through the decades, NABHR managed a number of highway research projects that have provided crucial knowledge regarding highway technology and pavement performance.
NABHR has since been renamed to the Transportation Research Board (TRB), and continues to manage and promote transportation innovation through research.
Development of standard highway signage
In the early days of automobile travel, organizations called “automobile clubs” were formed to lobby for better, safer roads. One aspect of this was creating road signage, to display highway names/numbers and direct drivers to their destinations. Around the beginning of the 1900s, the Buffalo Automobile Club began establishing a signage network in the state of New York, and the Automobile Club of California began posting signs on main highways around San Francisco. Following suit, clubs all over the country worked to provide similar resources for their drivers.
In the 1920s, representatives from several states toured the US, gathering data to assemble some kind of standard for signs and road markings. Their research led to the development of the idea that sign shapes would reflect the level of danger of a situation—circular signs represented dangerous situations, such as railroad crossings, octagonal signs indicated lesser dangers, such as stopping at intersections, and diamond and rectangular signs were associated with the least amount of danger. Circular signs were chosen for the most dangerous situations because they were the least frequent, and the more circular a sign was, the more material waste manufacturing the sign would produce. Shapes became a popular way of distinguishing between types of signs because signs were difficult to read at night, and shapes were more easily recognizable.
Soon after, in 1924, the First National Conference on Street and Highway Safety updated highway signage standards and proposed standardized colors—such as white text on a red background for stop signs. In 1935, the first Manual for Uniform Traffic Control Devices (MUCTD) was printed, setting standards for regulatory, warning, and guide signs, as well as defining some pavement markings. This establishment of standard signage in the US helped streamline vehicular travel and increase safety on highways, through simple, easily-recognized signs.
Construction of Going-to-the-Sun Road through Glacier National Park
When Glacier became a National Park in 1910, only a few miles of wagon roads existed in the millions of acres of parkland. Park officials wanted to expand this small network by building a trans-mountain road, which would make some of Glacier’s wilderness more accessible to tourists traveling by car.
This road, known as Going-to-the-Sun Road, was built following National Parks Service (NPS) values of preserving the landscape and harmonizing with nature, reducing concerns that building infrastructure through the park would mar its integrity. The roads and bridges were constructed out of native materials, and blasts were kept to a minimum to reduce impact on the surrounding landscape. During the construction of the road, surveyors often had to walk several miles and climb a few thousand feet to get to work every morning, where they had to navigate narrow ledges and steep cliffs to take measurements. Animals encounters, such as with black bears and grizzly bears, also posed a constant threat.
The Going-to-the-Sun Road opened July 15, 1933, providing a route through the heart of the beautiful landscape of Glacier National Park. This highway helped encourage the idea that roads are not just a means of getting from one place to another. It does not focus on ease of transport or convenience, but instead on landscape preservation and environmental sensitivity. Going-to-the-Sun Road was the beginning of a long partnership between the National Parks Service and highway entities to build highways, through the most beautiful parts of the country, that both respect the landscape and provide a safe route of transportation for drivers.
The legacy of Route 66
The idea for an interregional link through the heartland of the United States was spawned in the 1910s. But this lay stagnant for a decade, only coming into fruition with the onset of interest in automobiles and federally funded highways. In the summer of 1926, this highway between Los Angeles and Chicago was officially named: Route 66. During the following decade, workers from dozens of states worked on the highway’s construction, and Route 66 was officially declared continuously paved and complete in 1938.
Route 66’s course through the Midwest allowed families to drive from LA to Chicago, linked rural Midwestern communities together, gave farmers the ability to transport produce in summer and winter alike, and routed truckers around more northern roads fraught with precarious weather and driving conditions. After nearly five decades of serving the Midwest, the road was decommissioned in 1985, but parts of it have been preserved. Route 66 has since been recognized as a “symbol of the American people’s heritage of travel and their legacy of seeking a better life,” becoming an iconic representation of the boom of automobile transportation and the romanticizing of road trips through America’s heartland.
The Pennsylvania Turnpike: the first toll road
One of the key roads in early US highway history was the Pennsylvania Turnpike. A 160-mile road stretching from Carlisle to Irwin, PA, the Pennsylvania Turnpike opened in 1940 and was the first major toll road and the first long-distance, highspeed, limited-access road in the country. This toll road was predicted to have an average traffic volume of 1.3 million vehicles per year, but actual usage surpassed expectations, reaching an upwards of 2.4 million vehicles a year. The Pennsylvania Turnpike’s massive success helped establish the country’s burgeoning dream: a future of highspeed automobile travel through a nationwide network of roads. Today, the Turnpike extends across the entire state of Pennsylvania, connecting the metropolitan areas of Philadelphia, Harrisburg, and Pittsburgh.
Creation and development of the Interstate Highway System
Privately and publicly owned toll roads, such as the Pennsylvania Turnpike, provided cars with routes for highspeed, long-distance travel. But as the need for more transportation infrastructure steadily increased, the idea of building roads with money from an increase in taxes, rather from through tolls, began to come to fruition as a more effective way of building highways.
Car companies and tire manufacturers alike lobbied for these “free” roads, because public roads would provide the necessary infrastructure for their products without needing to fund the infrastructure themselves. Over the course of a decade, plans for this network of freeways were made, but it wasn’t until President Eisenhower signed the Federal-Aid Highway Act in 1956 that the Interstate Highway System was created. This act created 41,000 miles of a “National System of Interstate and Defense Highways” and allocated $26 billion for the building of this network. The money would come from a one-cent increase in gasoline tax and would provide the country with highspeed, long-distance travel, as well as an evacuation route to and from major cities during the event of a nuclear attack.
Since then, the Interstate Highway System has been considered one of the greatest civil engineering projects in the US, extending 46,876 miles through all 48 contiguous states and Alaska, Hawaii, and Puerto Rico.
AASHO Road Test sets pavement design standards
Until the 1960s, new pavements were based on the design of similar pavements in similar traffic and environmental conditions. While this experience-based method often yielded successful roads, it lacked the ability to predict the life of a pavement for new situations, such as a higher traffic volume or heavier vehicles.
The American Association of State Highway Officials (AASHO), now the American Association of State Highway and Transportation Officials (AASHTO), recognized the need for scientific research on pavement performance. This spawned the idea for the AASHTO Road Test, which was a massive research project to develop relationships between pavement design, traffic, and performance. A 10-lane test track, composed of both asphalt and concrete pavements of various thicknesses, was built in Ottawa, Illinois. Beginning on October of 1958 and continuing until November 1960, over one million axles of different weights were applied to the pavement, meant to mimic the variety of traffic that roads can experience, allowing engineers to quantify the damage caused to the pavement by each axle load.
The results from the AASHO Road Test helped measure how pavement thickness and traffic can be related to the life of a pavement. The test is widely considered to be some of the most comprehensive and valuable research done in pavement engineering, establishing the concept of pavement serviceability.
Strategic Highway Research Program is established
The Strategic Highway Research Program (SHRP) was conceived in the late 20th century as a means of addressing the parts of the Interstate Highway System approaching the end of their design life. SHRP was authorized by Congress in 1987, beginning a five-year applied research initiative to develop technologies that would aid in repairing deteriorating highways and improve their efficiency and safety. Conducted under contract with universities and private organizations, SHRP initiated hundreds of research projects on asphalt, concrete and structures, highway operations, and pavement performance.
In the end, over a hundred products were developed through SHRP and guided into use by state and local agencies, so they could be implemented in highway maintenance programs. Successful technologies, such as the Superpave design system for asphalt and various nondestructive pavement testing technology, have demonstrated the success of SHRP and the crucial partnership between researchers and government agencies in pavement technology.
Interstate 70 through Glenwood Canyon: the final link of the Interstate Highway system
Opened to traffic in 1992, the construction of Interstate 70 through Glenwood Canyon in Colorado marked the symbolic completion of the Interstate Highway system. It was the final section of I-70 to be built, connecting the Denver metropolitan area to the rest of the state and rest of the country.
When the idea of completing Interstate 70 came about, directing it through Glenwood Canyon seemed to be an impossible task. A two-lane highway already wove through the canyon on one bank with the Rio Grande Western Railroad on the other, and between these two routes, there hardly seemed to be enough room for an even wider, four-lane interstate highway.
Other options for I-70 were explored both to the north and south of Glenwood Canyon. However, engineers and planners began to realize that Colorado’s mountainous terrain would require construction at high elevations and steep grades, environmental impact, technical challenges, and most importantly, high costs. The Glenwood Canyon route was determined to be the optimal path, and construction began in 1980.
The interstate was constructed as an elevated roadway, with the eastbound and westbound directions nearly on top of one another in the narrowest parts of the canyon. Engineers collaborated with environmental scientists to minimize all possible disruptions to the natural environment both during construction and implementation. Rest areas and recreational facilities were constructed along the canyon to direct human impact away from the more delicate sections of the canyon, and to provide opportunities to hike, bike, and fish. Today, the Glenwood Canyon portion of this interstate is regarded as an engineering marvel, due to its careful planning, environmentally-sensitive design, and breathtaking views.
Fixing America’s Surface Transportation (FAST) Act
The Fixing America’s Surface Transportation (FAST) Act, signed into law in 2015, was the first federal law in a decade that provided long-term funding for surface transportation infrastructure. It allocated $305 billion over five years for development and maintenance in road safety, public transit, and highway research. Though the FAST Act is mostly geared towards funding the maintenance of current transportation infrastructure, it provides transportation agencies access to critical funding for transportation upkeep and innovation for the next half decade.
Now, new tech is coming to surface transportation faster than ever before. Connected and automated vehicles and trucks, new sensors, drones, and new tech will make major changes to the way roads are designed and built and used.
Harvesting clean energy from roadways
While many engineers are concerned with the deleterious effects of vehicles on pavement, others are searching for positives: how can we use highway traffic to generate clean energy?
A research team at the University of Texas at San Antonio has been awarded a $1.32 million contract from the Texas Department of Transportation (TxDOT) to develop piezoelectric sensors that can be embedded in roadways and harvest energy. A car passing over one of these piezoelectric sensors creates a voltage, and that voltage can be converted into electricity. By lining an entire roadway with these sensors, the vehicular traffic that passes over the road can generate enough power to be pushed back into the grid, stored, or even light roads at night. Innowattech, an Israeli-based company, is developing a similar technology and has run a successful test section that points to this technology becoming a viable option in the future.
Energy can not only be generated from the pavement, but also from the wind that cars generate as they drive by. Dutch designer Daan Roosegaarde and civil engineering firm Heijmans Infrastructure have partnered to develop a project called “Smart Highways”—concepts to “make highways safer while saving money and energy.” One design concept is to place pinwheels along roads—like mini wind turbines—turning the drafts of air generated by passing cars into energy that can power street lights. In Dundee, Scotland, there is a wind turbine that spins in the wind of passing traffic. Created by a Pakistani entrepreneur, these turbines take advantage of both the high vehicle traffic and windy geographical location to harvest clean energy.
Even if the energy generated from these technologies is minimal at first, any amount of energy harvested can help offset the costs of powering these highways at night—a small, but significant step towards creating renewable highways.
Glow-in-the-dark, dynamic paint
As part of the same Smart Highways project, artist Daan Roosegaarde and Heijmans Infrastructure are also creating dynamic paint for highways that can reduce energy usage and increase safety.
The paint used in this project is photoluminescent, which means it soaks up energy from the sun during the day and uses that energy to light up at night. Glowing lane markings could reduce the amount of traditional street lamps needed to properly light the road, saving energy costs.
This paint would also have temperature-sensitive properties, such as changing color or displaying markings on the road that become visible during poor road conditions. Drivers would be notified of ice or slick surfaces by warnings on the pavement, allowing them to take measures to avoid crashing or hydroplaning. When the conditions subside, the markings would become transparent, returning the pavement surface normal.
Roosegaarde and Heijmans are testing their innovative paint concepts on a 500-meter section in the Netherlands. An artistic and technologically-savvy solution to highway safety, this dynamic paint furthers Roosegarde’s mission “to connect people and technology in artworks that improve daily life in urban environments.”
Concrete roads that can de-ice themselves
In cold regions, spreading de-icing chemicals or salt on roads is a necessary ritual during the winter. Such is a tedious but necessary task to prevent ice and snow from creating hazardous conditions for vehicles. But what if de-icing chemicals were no longer necessary? What if roads could de-ice themselves?
Conductive concrete may be the answer. By mixing steel fibers, carbon particles, or other electrically conductive material into concrete, an electrical current can be passed through the slab. During snowstorms, transportation agencies can pass currents through conductive slabs on their roads, causing the slab to act like a heating blanket and melting the snow on top of it. Researchers at the University of Nebraska—Lincoln have tested this technology on a 150-foot bridge near Lincoln, Nebraska with successful results. During 15 major snowstorms, the conductive concrete kept the bridge free of ice for only $250 per storm.
The Federal Aviation Administration (FAA) is interested in using this technology for airports. Embedding anti-icing technology in airport pavements would remove the need for de-icing vehicles or snow plows, thus expediting the de-icing process and reducing vehicle traffic on the tarmac. Developing and installing these conductive slabs is pricey, but could be worth their cost in specialized situations, such as airport tarmacs, hard-to-plow places, or critical areas where excessive snow is a nagging problem.
Making infrastructure more readable for autonomous cars
A challenge to autonomous vehicles is the decaying state of infrastructure. Fading lane markings, difficult-to-read road signs, and poorly-placed signs are all challenges to a computer-based system. To address this, 3M has launched a project called Connected Roads in order to develop low-cost solutions to making infrastructure more readable to autonomous technology. One method of doing so is by changing lane markings to reflect outside the visible spectrum, allowing these markings to be “seen” by autonomous vehicles even in inclement weather. Other changes include installing more reflective road signs and making signs more machine-readable. Making roads more compatible with new technology means updating current infrastructure technology.
The Texas Department of Transportation (TxDOT) has partnered with the Texas A&M Transportation Institute (TTI) to research the idea of embedding road signs with machine-readable code for autonomous vehicles. These road signs would appear the same to the human eye, but would contain code with additional information that autonomous cars could read, such as providing the date of sign installation or acting as wrong-way detection. This technology would also be able to inform DOTs if it needs to be repaired or replaced, helping DOTs maintain the quality of their highway signage.
An important step to preparing roads for autonomous vehicles is ensuring that the existing infrastructure can be easily interpreted not only by human drivers but by autonomous ones as well. Projects like 3M’s or TxDOT’s and TTI’s provide concrete solutions for communicating useful information to cars without disrupting the information that humans are used to.
Repurposing non-recyclable plastic waste in asphalt roads
In the United States, the most recycled material isn’t aluminum, glass, or paper—it’s asphalt. Over 70 million tons of asphalt are torn up from old roads and processed to be reused in new roads each year. Around the world, asphalt roads are recycled at the end of their service life and mixed with new asphalt. The recycling of this popular material may hold the key to another recycling problem: plastic waste sitting in landfills.
MacRebur, a UK-based firm, is on a mission to “help solve the waste plastic epidemic and the poor quality of roads we drive on around the world today." They have created an innovative road material design, mixing non-recyclable waste plastic with asphalt. Numerous roads around the world have been built using this design, and MacRebur claims that their mix is not only ecofriendly but produces longer-lasting roads.
This technology is also making its way to India. Chemistry professor Rajagopalan Vasudevan has developed an asphalt mix that contains finely shredded plastic waste, similar in concept to MacRebur’s. He has helped build hundreds of thousands of kilometers of roads in over 11 states in India and also argues that his roads are more robust than other roads without plastic.
These plastic roads must stand the test of time before they are trusted as viable plastic repurposing and road design alternatives. But if using waste plastics in asphalt is proven to be effective, it could be a significant contribution by the transportation industry towards environmental sustainability.
Dynamic electric vehicle charging: charging cars as they drive
Range anxiety, or the concern that an electric vehicle’s battery will not last long enough to reach the destination or the nearest charging station, is a common fear among electric vehicle drivers. While battery technology is progressing, long trips remain a major weakness for electric vehicles. Technology companies are looking to expand electric vehicle capabilities by developing innovative solutions to charging on the go.
Qualcomm Technologies is one company that is using Dynamic Electric Vehicle Charging (DEVC) to solve this problem. In DEVC, coils are embedded in pavement and send power up to a vehicle traveling across it. This allows a vehicle to charge while driving, potentially even exiting a highway with a battery fuller than when it entered the highway. This technology could enable electric vehicles to travel farther between charges than ever before, possibly even eliminating the need for large, heavy batteries, further saving cost and weight.
But even if Qualcomm’s tests are successful, the cost of implementing such a technology is a major hinderance—the price and hassle of tearing up roadways to install inductive coils may not be worth the benefit it gives to passenger vehicles. However, there may be a future for this technology in public transportation, where routes are standardized and vehicles carry more passengers. DEVC could be the next step towards fully-automated fleets of buses and taxis.
Drones overhead that monitor highways and predict maintenance
The Ohio Department of Transportation (ODOT) is looking towards an innovative technology to monitor their highways: drones. In collaboration with Ohio State University, ODOT is learning how to use drones to monitor and send traffic data to ODOT’s Traffic Management Center, where measures can be taken to improve traffic flow.
Other countries are utilizing drones for similar purposes as well. The National Highways Authority of India (NHAI) plans to use drones to do surveying for road projects, turning a process that take surveyors months to complete into a task that takes drones a few days. Drones can take pictures of structures, determine topography, and provide information about a project site in detail. They will also be able to predict maintenance, allowing for preemptive repairs and extending the structure’s lifetime and durability.
While highway maintenance drones are still in the research and development phase, the implementation of this technology may prove to reduce time, streamline construction projects, and eliminate the need for tedious manual tasks.