By ROBERT L. REID
Sensors, cameras, and other technologies are helping cities monitor and manage their streets better. Data from such "smart streets" are enabling engineers and other transportation experts to improve safety and the flow of traffic, speed up transit, and assist in the integration of autonomous vehicles onto America's roadways.
A street in today's digital age is more than just a route from the proverbial point A to point B. Thanks to the use of sensors, cameras, connected devices, and other data-gathering technology, the streets and their surrounding infrastructure can collect valuable information to help city leaders, urban planners, transportation department officials, and various types of engineers provide myriad benefits to the public. These include improving traffic flows and parking, making public transit more reliable and efficient, creating safer intersections, supporting electric and autonomous vehicles, monitoring weather and environmental quality conditions, scheduling maintenance work, assisting the police, and many more.
Dubbed "smart streets," the approach often involves electronic and information technology applications known as intelligent transportation systems (ITS). But the term smart street itself does not have a single, universal definition—it can involve different technologies, techniques, and goals, depending on where the street in question is located. The phrase is even used for roadway projects that don't rely on technology, and it is sometimes confused with the U.S. Department of Transportation's "complete streets" concept, which promotes making America's streets more accessible to people of all ages and abilities and for all modes of transportation, from walking to cycling to using public transit to driving a vehicle.
For the purpose of this article,
focused on the technology-based, data-collection version of smart streets. The sensors, cameras, and additional devices used to gather and share that data can be embedded in road surfaces, attached to streetlight poles, suspended from traffic signals over intersections, or attached to buildings along traffic corridors. Even the vehicles driving on the streets can be used to collect and share important data. This information can range from traffic speeds and volumes to weather or road conditions, congestion levels, and travel times between destinations. It can be transmitted to a central traffic management center to be analyzed by transportation professionals or sent directly to drivers or pedestrians via their mobile devices. It can be shared directly between a vehicle and a traffic light, or vice versa, or even be sent directly from one vehicle to another without human interaction.
Although many of the elements of smart streets involve the latest digital and wireless devices, some engineers say the concept evolved from longstanding transportation management systems. For example, the engineering firm AECOM began working with the U.S. Department of Transportation on computer signalization systems during the late 1960s and early 1970s, explains Bob Edelstein, Ph.D., P.E., PTOE, a senior vice president and ITS practice leader in AECOM's Fort Lauderdale, Florida, office. Over the decades, those legacy systems were improved and updated again and again, leading to today's more advanced technologies that will eventually enable the integration of connected and autonomous vehicles on American streets, Edelstein notes.
A key change over that period was the shift from "mostly reactive" responses to roadway problems to more proactive responses, Edelstein adds. Previously, when there was an accident or other problem that resulted in lane closures on a city street or freeway, "it would take a long time to actually find out and dispatch the right emergency response," Edelstein says. "But now we have a lot of data, a lot of sensors, a lot of technology out in the field, so information comes in to the control centers through fiber-optic communications, and we're able to get a real-time, situational awareness of what's happening on the roadway system."
This leads to faster responses to, for example, get injured people from an accident to a hospital or get the roadway system cleared and operating again, Edelstein explains. Moreover, it can help transportation officials learn about and thus anticipate problems with safety or congestion in particular locations so that they can develop mitigation measures "to avoid problems rather than just reacting to them," Edelstein concludes.
Matt Volz, P.E., a senior transportation project manager in the Kansas City, Missouri, office of engineering firm HDR, likewise notes that his firm has been installing sensors in roadways for the past 20 or 30 years to help track vehicle volumes and speeds. "We used to saw-cut loops into the pavement," Volz notes, referring to loops of copper coils that were installed in the road surface to detect the presence of vehicles and their speeds. But "the roadway is a very harsh and unforgiving environment for technology," he adds.
Devices set in the road surface itself, especially in regions subject to harsh winters, are easily cut or otherwise damaged by snowplows, road salt, or issues related to the "grit and grime and wear and tear of the road," Volz explains. As a result, the in-ground sensors can lead to increased maintenance costs and inconvenience-such as closing a lane to install, repair, or replace a sensor, notes Edelstein.
Moreover, sensors embedded in curbside parking spaces—used to track where parking is available—can generate inaccurate readings because of construction barriers or piles of snow. These devices often use electromagnetism to detect the presence of metal—in the form of a vehicle—above the sensor, which the snow would not trigger, notes Kris Carter, the cochair of the Mayor's Office of New Urban Mechanics in Boston. Thus, the sensor would report that a parking space was unoccupied at a time when it could not actually be used.
As a result of such problems, experts say that transportation management professionals are moving away from installing smart street devices within the actual asphalt or concrete of the roadway. The in-ground approach is still used, but other approaches are increasingly popular—including side—fire radar systems, elevated cameras, and devices located on poles or other structures along the road. In the future, devices onboard vehicles traveling along the road will also provide critical data.
A pilot project in Boston, for instance, involved the installation of more than 60 devices at the intersection of Massachusetts Avenue and Beacon Street, a site that had experienced numerous vehicle crashes as well as at least two fatal accidents, says Carter. Working with the telecommunications firm Verizon, the city deployed a series of video cameras, electromagnetic and infrared sensors, and numerous other systems. The cameras were mounted on poles or adjacent properties, and the sensors were located in the roadway, on poles, or in traffic cabinets along the route, notes Carter.
The devices helped traffic managers conduct predictive crash analyses, examining what behaviors might be making the intersection unsafe or whether the signal timing, the design of the roadway, the pedestrian crossing distances, or other factors were at fault, says Carter.
Ultimately, the intersection was redesigned to improve safety, Carter says, with a protected area for cyclists, signal timing that provides pedestrians with more time to cross, and changes to how vehicles turn from a bridge onto Beacon Street.
Although it is not feasible to install 60-plus devices at every intersection, Carter explains that the pilot project served as "a learning curve for us and Verizon on what works, what doesn't, what combination of things [we need], and what can be turned off and still get the same accuracy."
In Detroit, the city is working with Miovision Technologies Inc., headquartered in Kitchener, Ontario, Canada, to install elevated cameras at hundreds of intersections as part of a remote traffic-signal maintenance system. The technology for that system was put on display during the latter half of 2018 in a six-month-long demonstration project dubbed "the world's smartest intersection." It involved technology installed at five intersections along a roughly 1 mi long section of Larned Street, just outside Detroit's central business district. The demonstration project coincided with an ITS conference being held in Detroit that year.
The project's goal was to study the capabilities of the camera technology and adapt it to the city's existing traffic-signaling system, which in recent years had suffered from power supply issues and other problems, notes Sunny Jacob, P.E., the head transportation engineer in Detroit's Traffic Engineering Division. Traffic engineers had even previously relied on citizen complaints or reports from other agencies to determine where specific traffic signals were malfunctioning, Jacob explains.
Now, the use of fish-eye cameras will provide real-time images of all four sides of an intersection, making it possible for Detroit's traffic managers to study the movement of vehicles through the intersection, including counting how many vehicles go straight and how many turn, in which direction they turn, and what they do after turning, notes Tony Geara, P.E., PTOE, an ITS and traffic engineer for the city.
The system will also provide telemetry on which traffic signals are working properly and which require attention, saving the city from potentially expensive but unnecessary maintenance efforts, says Jacob. Because the system also provides historical information on traffic-signal performance, the city will be able to easily determine if a signal was working properly at the time of an incident or accident, Jacob adds.
Data on near misses involving vehicles and pedestrians or cyclists is critical to setting the timing of traffic lights at intersections, notes Dan Corey, P.E., M.ASCE, AECOM's deputy ITS national practice lead in the firm's Philadelphia office. "As people cross streets, how are they crossing—legally or not legally?" Corey asks. Cameras can capture the movement of pedestrians, Corey notes, and then artificial intelligence tools can help analyze the close calls to help traffic managers "make sure drivers stay aware of pedestrians in the area," he explains.
At present, the data collected by cameras and sensors in various cities are often sent to a centralized transportation management center for each municipality, where engineers or other transportation professionals review and analyze the information or images to respond to traffic incidents, make decisions about road or signal maintenance, and deal with other concerns. Sometimes, the information is sent to drivers or pedestrians so they can react to incidents in real time. The pedestrians might receive information via their smartphones, while drivers can be contacted via phones or a local radio broadcast. Volz says communications of data collected is key to the use of smart technologies. The FM high-definition radio system in his car receives graphical data about the weather, traffic, road conditions ahead, and even alternate routes he might want to use. It also has satellite, cellular, and other wireless communication systems through transponders.
The engineering firm Arup is working with the New York State Department of Transportation on an integrated corridor management program along Interstate 287 in the state's Rockland and Westchester Counties. Known as the Lower Hudson Transit Link, the project features vehicle messaging signs, sensors that detect the volume and speed of vehicles, and meters designed to help prevent traffic from backing up on the entrance ramps and spilling over onto arterial roads, notes Trent Lethco, AICP, a principal in Arup's New York City office. Designed to also support a bus rapid transit system, the project will bring together highway and transit engineers in a traffic management center "to ensure that if any issues come up, they get addressed quickly and keep things moving," Lethco says.
In addition to collecting data from technology on the buses and sensors across the corridor, the project uses a predictive traffic modeling software tool that enables transportation managers to use traffic conditions, weather information, and other inputs "to determine if they need to be prepared for incidents because of the probability that rain will cause crashes or delays from growing congestion," Lethco explains.
In Columbus, Ohio, the engineering firm HNTB, which has its headquarters in Kansas City, Missouri, has been assisting the city for roughly the past decade to develop and operate the Columbus Traffic Signal System. This work included the design and construction of a new traffic management center, the installation of some 750 mi of fiber-optic cables, and other measures to create a "streamlined, connected system across central Ohio," involving Columbus and its surrounding suburbs, notes Matt Graf, P.E., an HNTB project manager. To ensure that the system will function well into the future, the city decided to install more fiber-optic capacity than it currently needs—using cables with hundreds of strands instead of the dozen or so that a more traditional signal system might require, Graf says. This will not only help Columbus's transportation managers be better prepared for connected and autonomous vehicles but will also enable other departments and agencies within the city government to use that connectivity for nontransportation projects, Graf explains.
Like vehicles themselves, the transportation management industry is becoming increasingly automated, with vehicle-to-infrastructure and even vehicle-to-vehicle systems likely to proliferate, suggests Ben Pierce, the transportation technology program lead in HDR's Cleveland office. In such automated systems, a public bus, for example, can approach a stoplight and communicate electronically with the light to ensure that it stays green long enough for the bus to pass through the intersection. Likewise, the walk signal can be extended for a wide street immediately after a full bus lets off passengers or "counters could recognize the number and speed of approaching bicycles and give cyclists priority at intersections," according to a 2019 report,
Blueprint for Autonomous Urbanism, Second Edition
, from the National Association of City Transportation Officials, based in New York City. In the future, automated windshield wipers on cars might send out alerts to other approaching vehicles when heavy rain starts, says Volz.
Although a human operator is currently involved in most traffic management decisions, "our industry as a whole is shifting," Pierce notes, and these automated systems "will continue to change the nature of what sensors we deploy."
At the same time, the human factor can be essential to maintaining a system's credibility. "As you automate things, you get a lot of false positives-a lot of false warnings that could erode the public's confidence in the information you're putting out there," notes Volz.
Even so, advances in technology are assisting or replacing certain road-management efforts that were once performed manually. For example, the city of Savannah, Georgia, previously relied on a half-dozen interns to subjectively assess the condition of roughly one-third of its road network each year. This meant that the entire 700 mi assessment took three years to complete and might force city officials to include information that was already outdated when it planned its road paving and maintenance schedule. So the city adopted a technological solution from RoadBotics, of Pittsburgh, that involved the use of smartphone images, an assessment by an artificial intelligence system, and a data-visualization platform created via geographic information system mapping and time-stamped images. Savannah's transportation managers were able to complete their most recent road assessment in less than three months and at a cost of just $50,000—versus $130,000 for its traditional, three-year-long approach, according to the RoadBotics website.
In Detroit, an attempt to change signal timing previously required a manual traffic count made by two people sent into the field, notes Jacob. Likewise, in Boston, gathering certain parking data involved sending "a person with a tablet walking around the street for a year on a randomized route," says Carter. Both cities have now automated those activities.
The backbone of smart street efforts is often the installation of communications infrastructure, especially extensive networks of fiber-optic cables, notes Katherine Zehnder, P.E., PTOE, M.ASCE, an HNTB vice president in the firm's Columbus office. In Columbus, Zehnder is working on a comprehensive, citywide plan to connect 58,000 streetlights to the city's fiber-optic infrastructure, enabling the future use of smart street technology. Such "smart poles" can not only help count traffic and monitor how long a car has been parked in a curbside spot, they can also feature light-emitting diode (LED) signage that alerts drivers to how fast they're driving and provide Wi-Fi service to pedestrians and drivers. They can even communicate with electric vehicle charging stations (see figure on page 66).
By connecting the streetlights to the city's fiber-optic network, additional smart technology opportunities are created. For instance, the smart poles can host pollution and air-quality control monitors and even carry acoustical sensors to help provide triangulation services to the police for investigating gunshots, among other capabilities.
In Boston, the city's transportation managers are also installing smart streetlights and "adaptive signal technology" that enable traffic lights to communicate with each other to adjust their timing and keep traffic moving safely. At the same time, private developers also increasingly require the installation of new fiber-optic capacity between buildings and the connected streetlights. "As things are getting smarter and more things need fiber, we're experiencing an uptick in the number of people who need to make physical connections within the streets," notes Amy Cording, the interim director of engineering for the Boston Transportation Department. This leads to more and more trenches being cut across the city, all of which must be completed during the region's weather-compressed construction season, Cording says.
To better manage such disruptions, the city now requires that any project of a certain size or that involves construction along a certain length of street must also install ductwork that has enough extra fiber-optic capacity to avoid the need for repetitive trenching. As Cording explains, "We're saying: if you're going to dig up this roadway, provide us with the extra fiber capacity so that when your building comes online and your customers show up and want to be hooked up, the blank conduit is already there."
The technology for smart streets also has implications for the curbs along such streets. AECOM is developing pilot projects that focus on the use of curb space for parking or making pickups or deliveries at given times of the day, says Corey. These "flex zone" projects will consider variable pricing models to cover, for example, freight services during business hours, ride-hailing services throughout the day, or drivers who want to come to downtown shops or restaurants in the evening, Corey explains.
"Curbs are kind of the next frontier for all of this type of work," notes Lethco, who points to an innovative approach in San Francisco known as SFpark. This project uses sensors and wireless communication technology "to collect and distribute real-time information about the number and location of available parking spaces," according to the 2014 report,
Urban Mobility in the Smart City Age,
which Arup and The Climate Group, which has offices in New York City, London, and New Delhi, prepared for Schneider Electric, based in Rueil-Malmaison, France. "SFpark uses demand-responsive pricing to open up parking spaces on each block and reduce circling and double-parking in congested areas. Parking fees may vary by block, time of day, or day of the week," the report states.
Looking ahead, civil engineers see a variety of futures for the role that they can play in the design, development, and operation of smart streets. For example, the engineering firm Stantec, which has its headquarters in Edmonton, Alberta, Canada, has partnered with the University of Alberta to help create a connected vehicle test bed that features roadside technology and a central traffic management laboratory to monitor vehicles in a variety of settings, including a rural freeway, an urban freeway, and urban arterial roads. The applications being tested include road safety alerts, pedestrian detection alerts, vehicle-to-vehicle safety messaging, and priority signal control for mass transit.
The technology for smart streets is also moving beyond just gathering data on traffic, notes Corey. "We're looking toward taking that data and creating more of a connected community, and with that connected community you're looking at multiple types of transportation," including bicycles, pedestrians, autonomous shuttles, electric scooters, and ride-hailing services, Corey explains.
Traffic managers might also benefit from approaches that gather data without the need to install or maintain sensors, cameras, or other devices. For instance, some city and state departments of transportation are already using information from Google's Waze navigation software app, which lets individual drivers report road congestion, accidents, or bad weather, notes Volz. Traffic management centers "can not only look at the sensors and the cameras they have on the roadway but also get this crowd-sourced data and use it as another way of detecting where things are happening on the roadway," Volz says. "We typically need a second verification before putting up a message or broadcasting an alert" about Waze-reported incidents, he adds.
One potential roadblock to the growth of smart street systems, however, is the question of privacy. Although several engineers contacted for this article stressed that their clients are concerned and careful about any data collected, at least one city-San Diego-is currently being sued by a citizens' group in a dispute over the information gathered by its network of smart streetlights.
A question for civil engineers to consider is what role they will play in these systems, which rely so heavily on other disciplines, such as electrical engineering and software or computer science engineering.
For Zehnder, civil engineers will always play a central part in smart street efforts because "civil engineers are closest to the citizenry. We interact with the public a lot more than other types of engineers because we typically work for public agencies."
At the same time, notes Graf, "the technology thing isn't going away! It's becoming cheaper and more capable and more reliable." So he feels civil engineers "need to make sure they have the awareness and overall knowledge of it so they will include these things in their designs."
Jagannath Mallela, Ph.D., a senior vice president in the Washington, D.C., office of the engineering firm WSP, stressed in written answers to
's questions that "a command of traditional civil engineering disciplines—such as materials, hydraulics, hydrology, structural, geotechnical, pavement engineering, et cetera—is still central to planning and designing smart streets. However, a deep understanding of material chemistry, sensor technologies, mechatronics, control systems, data science, and computer engineering is vital for civil engineers in this era of fast-paced change—where the physical, digital, and biological worlds are coming together to create new and, hitherto unimagined, possibilities."
For the cities installing smart technology, "it's easy to believe the hype … that if you buy this one widget, it will solve everything for you [and] make traffic flow like in a car commercial!" notes Carter. But "cities are messy and complicated, and even if you solve one problem, two more will emerge," he explains. "The technology doesn't answer the questions for you—it just gives you more information to work from. You still have to use sound engineering judgment to make the decisions that prioritize your objectives."
Robert L. Reid is senior editor and features manager of
Civil Engineering, February 2020, © American Society Of Civil Engineers. All Rights Reserved