Autonomous vehicles – Implications for highway infrastructure

Autonomous vehicles have the potential to reshape transportation for the better. Their safety improvements are a potential boon to public health and safety since they can reduce human error on roadways.

Their ability to improve road capacity, mobility and the productive utilization of our travel time also promise significant convenience, productivity, and accessibility for all people, including young, elderly, and disabled.

Though most of these technologies are still in a developmental or testing stage, it is clear that autonomous vehicles have many advantages. The first benefit is safety as they have autonomous guidance systems to continually scan the road for other vehicles, bicyclists, pedestrians, traffic patterns, and potential hazards, and accurately navigate via a combination of onboard sensors and GPS data.

Integrated with vehicle communication systems, they can also share information with other vehicles, allowing them to perceive the road ahead in great detail than a human driver or standalone sensors. The autonomous vehicle of the future can represent a quantum leap in safe transportation by combining these systems and capabilities with state-of-the-art vehicle construction and safety equipment.

Below, we have summarized some of the key benefits and challenges that autonomous vehicles will bring about in our pursuit of better, safer, and cleaner transportation.

Benefits

  • Reduced drivers’ stress and increased productivity. Drivers can rest, play, and work while traveling.
  • More independent mobility for non-drivers, reducing chauffeuring burdens, and transit subsidy needs.
  • Reduce costs for taxis services and commercial transport drivers.
  • Reduce crash risks and insurance costs.
  • Increased road capacity. Reduced congestion, roadway, and parking costs.
  • Reduced energy consumption, pollution, and emissions.
  • Facilitate car sharing and ridesharing, reducing total vehicle ownership and travel and associated costs.

Challenges

  • Increased vehicle costs as it requires additional vehicle equipment, services, and fees.
  • Additional crashes caused by system failures, platooning, higher traffic speeds, additional risk-taking, and increased total vehicle travel.
  • Reduced security and privacy due to system vulnerabilities, information abuse (hacking), location tracking and data sharing, etc.
  • Increased infrastructure costs, higher roadway design, and maintenance standards.
  • Loss of jobs for drivers
  • Social equity concerns because of the lack of affordable mobility options, including walking, bicycling, and transit services.

Now, the deployment of fully autonomous vehicles will require not only a suite of new technologies but also changes to the highway infrastructure on which those vehicles will operate. Autonomous vehicles being tested today rely on clear pavement markings and legible signage to stay in their lanes and navigate through traffic. They require dedicated lanes to allow platooning (numerous vehicles driving close together at relatively high speeds).

Therefore, in order to accommodate autonomous vehicles in highways and side roads in urban and rural areas, we will require elaborate public planning, maintenance standards, regulations, and additional public infrastructure, including special signs, roadway markings, signals, and transponders, that will impose external costs.

Shared autonomous vehicles will need docking stations and passenger loading areas. The policymakers must decide whether to build special autonomous vehicle lanes, price them and how to regulate their operation to maximize total benefits.

In today’s transition period, which is likely to last several decades, the Federal Highway Administration (FHWA) plays a crucial role in administrating the Manual on Uniform Traffic Control Devices (MUTCD), which sets standards for all traffic control devices, including signs, intersection signals, and road markings.

FHWA is in the process of updating the 2009 MUTCD to address issues specific to autonomous vehicle technologies. However, state compliance with MUTCD is voluntary, and not all states uniformly apply all standards. In 2018, Audi reportedly announced that it would not make its new Level 3 autonomous vehicle technology, because of laws, insurance requirements, and things like lane lines and road signs that change from one state to the next. Other automakers have made similar complaints.

Despite national standards based on MUTCD, not all states maintain their highway markings at a level that would be useful to guide autonomous vehicles. Inadequate road maintenance may affect the pace of autonomous vehicle deployment. Some 21% of major U.S. roads are in poor condition, and a road with many potholes or temporary pavement repairs may also lack continuous lane markings.

Many minor roads, which are generally responsible for the county or municipal governments, lack road-edge lines and centerlines, potentially making it difficult for autonomous vehicles to position themselves correctly. Dirt and gravel roads pose particular challenges for autonomous vehicles, as they generally have no pavement markings, and cameras may be unable to detect potholes or edges in low-visibility conditions.

Another challenge is that over time, lines and highway markings may fade. Automakers and developers are required to find new ways for autonomous vehicles to navigate, including greater use of guardrails and roadside barriers, sensors, and three-dimensional maps.

If highly detailed mapping is deemed to be a replacement for visual cues such as lane markings, transportation agencies, and automakers must need to develop an open standard so that all vehicles will understand the mapping technology. V2X communications through DSRC and cellular may evolve to provide a mechanism for new types of vehicle guidance.

Notably, the Transportation Research Board (TRB) has been evaluating how states should start planning, developing, and standardizing the types of connected vehicle infrastructure required to deploy fully autonomous vehicles. TRB’s research focuses on how cash-strapped transport agencies can identify the significant investments that, in turn, will be needed to implement connectivity in addition to regular maintenance of highways, bridges, and other traditional infrastructure.

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