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Analysis & News on the Future of Public Finance

CSG AV Technology Hits a Speed Bump

While cities deal with the current simpler forms of technology-based transportation, autonomous vehicle development may not be as imminent as some would hope. The International Institute for Highway Safety released the results of its latest testing of autonomous vehicle performance. For proponents, the results may be disappointing.

Evaluations of adaptive cruise control and active lane-keeping show variable performance in typical driving situations, such as approaching stopped vehicles and negotiating hills and curves. The early results underscore the fact that today’s systems aren’t robust substitutes for human drivers. Do the systems handle driving tasks as humans would? Not always, tests showed. When they didn’t perform as expected, the outcomes ranged from the irksome, such as too-cautious braking, to the dangerous, for example, veering toward the shoulder if sensors couldn’t detect lane lines.

Adaptive cruise control (ACC) maintains a set speed and following distance from the vehicle in front. It is designed to slow for cars ahead and can come to a full stop but may not react to already-stopped vehicles. ACC doesn’t react to traffic signals or other traffic controls. Active lane-keeping provides sustained steering input to keep the vehicle within its lane, but drivers must continue to hold the wheel. On SAE International’s scale from zero autonomy to Level 5 full autonomy, the combination of ACC and active lane-keeping is Level 2. They can assist with steering, speed control, and following distance, but the human driver is still in charge and must stay on task.

The 2017 BMW 5-series with “Driving Assistant Plus,” 2017 Mercedes-Benz E-Class with “Drive Pilot,” 2018 Tesla Model 3 and 2016 Model S with “Autopilot” (software versions 8.1 and 7.1, respectively) and 2018 Volvo S90 with “Pilot Assist” were evaluated. All five have automatic emergency braking systems rated superior by IIHS.

Engineers evaluated ACC systems in four different series of track tests to see how they handle stopped lead vehicles and lead vehicles exiting the lane, and how the systems accelerate and decelerate. One series involved driving at 31 mph toward a stationary vehicle target with ACC off and autobrake turned on to evaluate autobrake performance. Only the two Teslas hit the stationary target in this test.

The same test was repeated with ACC engaged and set to close, middle and far following distance in multiple runs. With ACC active, the 5-series, E-Class, Model 3, and Model S braked earlier and gentler than with emergency braking and still avoided the target. The cars slowed with relatively gradual decelerations of 0.2-0.3 gs, braking in the same manner no matter the distance setting. Braking before impact was earlier for the Teslas than for the 5 series and E-Class.

Not all of the results were negative. The technology is often bundled with forward collision warning and autobrake, and research by IIHS and HLDI has found crash-reduction benefits for these systems combined. A federally sponsored study found that drivers using ACC have longer, safer following distances than drivers who don’t use ACC. Still, IIHS tests indicate that current ACC systems aren’t ready to handle speed control in all traffic situations.

What are the implications for transportation and related credits? The future is farther away than many have projected. This gives more time for municipalities and states to develop standards, create policies, and determine funding streams which may arise from the use of autonomous vehicles. For sectors which might be transformed as the technology can be implemented (healthcare is an example), the potential impacts may be more long term than short term.