Some Thoughts on the Future of Transportation Engineering

In honor of the 60th anniversary of the Journal of Transportation Engineering, we are publishing two articles, one on the history of the Journal and one on prospects for the future of transportation engineering.

Predictions of the future of transportation engineering have a long history of being incorrect. Some predictions are fanciful, such as travel to the moon via a projectile. Some predictions are overly optimistic, such as the expectation of common urban air travel from 50 years ago. Some predictions lack imagination, such as the prediction that the market for home computing would be minuscule.

This article will focus on the revolutionary changes in transportation that are occurring right now and will be continuing over the next decades. These changes include (1) automation and connectivity, (2) alternative fuels and fuel economy standards, and (3) the availability and use of so-called big data. I do not believe transportation has seen such drastic changes since the early twentieth century, which was a time when motor vehicles became a dominant mode of travel, petroleum products became the fuel of choice for transportation, and airplanes first appeared.

First, vehicles are becoming more automated and starting to communicate. Basic automation and communication technologies have been around for several decades. At Carnegie Mellon University, we just celebrated 30 years of research on automated vehicles. Initially the vehicles were fairly primitive: I remember one pioneering vehicle programmed to follow straight lines. It tried to go up a tree rather than follow a pathway in Schenley Park. But the Carnegie Mellon work continued and resulted in winning the 2007 DARPA urban challenge, which involved obeying all traffic regulations over a 60-mile course (DARPA 2015). Now there are driverless vehicles for off-road driving, for agriculture, for space exploration, and for on-road driving in traffic. Google (now named Waymo Division within Google parent Alphabet) reports that its autonomous vehicles have traveled more than three million miles in automated mode (Bhuiyam 2017).

Although there are numerous technical and policy barriers to overcome before we routinely see self-driving vehicles on the roads, we can expect to see increasing automation and increasing communication between vehicles and infrastructure. Most motor vehicle manufacturers are already offering packages of automated driving aids and improved sensors. A good example is a back-up camera and warning to prevent slow-speed, backing-up collisions. Benefits from all of this automation should include fewer crashes, less congestion, better traveler information, and more fuel-efficient driving. With truckers eager for fuel savings, vehicle platooning with headways shorter than usually assumed in traffic engineering are already being seen on our roadways. Connected-vehicle communications and automation aids will increase the amount of platooning and reduce its risks. As another example, it is always annoying when vehicles in a queue fail to start up when the light turns green. Adaptive cruise control is a simple technology that can manage these starts and make traffic flow more smoothly.

What are the implications of these new technologies for our roadway infrastructure? Biehler et al. (2014) looked at some appropriate policies. For example, roadside message signs will not be necessary with an entire fleet of connected vehicles. In rural areas, moving farm and other equipment should be easier and safer with communication connectivity and improved traveler information. In the short run, Biehler et al. recommend moving ahead on installation of dedicated short-range communication equipment with traffic signal upgrades to enable future communications. Because dedicated short-range communications can be used in existing vehicles, the introduction of widespread connectivity could happen relatively quickly.

There are some big uncertainties in the Biehler report. Will crash reduction, better traveler information, and platooning be sufficient to reduce congestion and thereby make capacity expansion unnecessary? Will safer vehicles be designed to downsize and achieve better fuel economy? How much extra travel will result from making driving less burdensome and, eventually, available to population groups for which driving is now difficult or impossible? How much and in what fashion will traffic engineering procedures and standards require change? These are pressing questions that transportation engineers will have to answer in the next few decades.

Beyond infrastructure and vehicle impacts, there will also be a wide range of effects on virtually everything and everyone connected with transportation: freight systems, public transportation, taxis, the insurance industry, component suppliers, parking lot providers, and real estate developers. Transportation engineers will have to change their assumptions about traffic flow and driver behavior. Automation and connectivity are truly revolutionary changes in how transportation performs.

As noted earlier, vehicle automation and connectivity will likely affect the amount of travel overall as individuals with impairments or those having other tasks to perform take advantage of driverless vehicles. At the same time, telecommuting and better communications may reduce overall transportation demand.

Two other significant in-vehicle changes are increased use of alternative fuels and increasingly stringent fuel economy standards. For decades, petroleum-based internal combustion engines were prevalent. Concerns about national energy security, climate change, support of agriculture, long-term petroleum scarcity, and (old-fashioned) money saving are motivating a variety of alternative-fuel vehicles on the market. Most U.S. light-duty vehicles already operate with 10% ethanol biofuels. In the future, we will likely have a variety of fuels in regular use, including natural gas, biofuels, and grid electricity. Different kinds of transportation infrastructure will be required, such as residential charging stations. For vehicles still relying entirely on petroleum for fuel, sophisticated technology and downsizing will be required to meet fuel economy standards.

Long-standing reliance on gasoline taxes for transportation financing will be a major problem in this new environment. Alternative-fuel vehicles and new fuel-efficient vehicles will pay lower or no gasoline taxes. Coupled with a reluctance to increase tax rates in line with rising costs and inflation, this reduction in taxes is already causing major problems for transportation providers. Even though Pennsylvania has bucked the trend of declining revenues, the underlying paradigm of gasoline taxes will need to be replaced by general-fund appropriations, a mileage tax, or some other user fee.

For a final technology change in transportation, we are in the new era of big data and powerful computing. Video cameras are cheaper and becoming much more widespread. They can provide real-time vehicle counts, vehicle speeds, incident detection, and pavement condition. Smartphones provide a means of tracking individual travelers in addition to communicating with vehicles, infrastructure, and the Internet. Transportation agencies should be able to rely on private providers of volumes and travel times. Unmanned aerial vehicles—drones—provide a new way to gather information. Transportation engineers must identify the best way to use this new flood of information to better manage the transportation system.

Shared services and new social media are also beneficiaries of big data applications. Transportation systems have excess capacity in uncongested or idle periods. Ride-sharing services are already leading to operational efficiencies, and the potential for greater improvement is evident. Vehicle sharing will also lead to changes in vehicle ownership, likely leading to an overall decline in the number of vehicles licensed.

Big data applications also highlight opportunities for multimodal coordination and integration of multiple functions. Transportation, environmental monitoring and management, energy systems, and other infrastructures will become much more integrated and hopefully better managed.

The coming technological changes—automation and connectivity, alternative fuels and fuel economy standards, and the availability and use of big data—along with associated management and policy challenges, will profoundly affect our transportation system, both now and in the next few decades. This discussion focused on roadway transportation, but these technologies will also revolutionize other modes. In railroads, the newest step in automation is called positive train control. In aviation, considerable automation has already been introduced in cockpits, and what is called next-generation air traffic control is under development. In both aviation and railroads, alternative fuels and big data are affecting how each mode is managed and performs.

For the Journal itself, we are seeing changes in its management and use. We have already moved the submissions and review process from reliance on paper and conventional mail to an entirely digital process. Downloads of articles are a direct measure of article impact, and the number of downloads is likely to replace the counting of citations to help assess impact. More and more calls for open access are occurring, and we will have to adopt a different business model to continue. However, we do not expect that the role of the Journal as an authoritative repository of knowledge will change.

In sum, we can expect great change but also great opportunities. I think it is a very exciting time to be transportation engineer.