Setting speed limits based on safety, not driver behavior

The 85th percentile rule in speed limit setting—an arbitrary but longstanding convention—has begun to weaken in recent years, with new guidance now allowing for lower speeds. FHWA’s USLIMITS2, for example, allows for speeds down to the 50th percentile in certain cases. Now there’s a growing push to take observed vehicle speed out of the speed limit equation entirely.

The persistence of pedestrianism

An investigation of the “persistence of pedestrianism,” written by Peter Norton, explores the history of both the rise of the dominance of automobiles as personal transportation and the continuing pushback by pedestrian advocates against this dominance from the 1920s to the 1960s. It is a fascinating look at how our perception of the urban landscape and mobility has been shaped by social and commercial forces as well as a rejection of the idea that most Americans drive because they prefer auto travel over walking. Norton instead contends that the cause and effect have been confused in most transportation analyses; people don’t walk, not because driving is their preferred method of travel, but because walking has been made so difficult.

Places with most crash exposure also fear enforcement bias

Low-income and minority Americans face a dilemma: They are disproportionately victimized by our transportation system. And while law enforcement could help, those same Americans are subject to profiling and fines that can lead to economic ruin. SSTI’s mid-November Community of Practice meeting, attended by CEOs and top staff from a dozen state DOTs, took on this problem. Jill Locantore, executive director of Walk Denver, gave us permission to share her presentation, and we can also summarize the thrust of the conversation.

Nighttime pedestrian fatalities soar

While other crash types have gone down, pedestrian and bicycle crashes continue to rise, and crashes happening at night account for 90 percent of the increase in pedestrian fatalities in the last ten years. A recent article asks, “Why?” but comes to no definitive conclusion. The authors cites possible factors for the rise in nighttime pedestrian fatalities: A general increase in people walking and biking for transportation, larger vehicles such as SUVs are more deadly to those outside the vehicle; more people are working at night; and new autonomous technologies do not do well detecting pedestrians, especially in low-light conditions. One factor not mentioned in the article is the number of lighted devices now in vehicles, but research in this area appears to be slim.

More sharp curves make roads safer

Unlike other risk factors such as speed or impairment—where more is not safer—increasing the number of sharp curves on a road segment appears to lower the risk of crashing, according to a new paper in the journal Accident Analysis & Prevention. Curves carry a level of inherent risk—they’re more dangerous than a straight segment of road, independent of other risk factors. As this paper points out, a decrease in a curve’s radius can make it safer, as can an increase in the number of sharp curves on the road itself.

Parents don’t always agree with practitioners about safe cycling routes for kids

Bicycle Level of Traffic Stress, a system for rating bicycle routes from low- to high-stress based on factors like vehicle speed and separation from traffic, has been gaining traction nationwide as an approach for identifying needed investments, evaluating the overall completeness of bicycle networks, and even making project ranking and selection decisions. However, a recent study indicates parents’ perspectives about “low-” and “high-stress” environments don’t always align with transportation practitioners when it comes to the safety of their children.

Auto-braking is becoming more common, but the tech is still evolving

One hope for reversing the growing death toll among pedestrians and cyclists lies in technology that senses crashes before they happen and avoids them. About half the new cars sold have automated emergency braking technology, and these systems have the potential to prevent thousands of crashes each year. But AEB in some cars is far from perfect, as a recent AAA report shows. Even under ideal conditions, the cars tested often hit pedestrian dummies.

Bellevue, WA, plans to use AI to leverage cameras for safety

Agencies that aspire to achieve zero traffic fatalities need to know where to invest for the biggest crash reductions. Advances in artificial intelligence are allowing DOTs to leverage their existing camera technology in order to extract large quantities of data that can then inform decisions about how to improve or control intersections. The city of Bellevue, WA, recently announced a plan to study footage from its traffic cameras in order to “analyze the correlation between past collisions” and near misses, according to a press release.

It’s not distracted walking that is killing NYC pedestrians

“[NYC]DOT found little concrete evidence that device-induced distracted walking contributes significantly to pedestrian fatalities and injuries.” So concludes a recent report examining whether device-distracted walkers are killing themselves by stepping out in front of motor vehicles. It’s dangerous driver behavior—speeding and failure to yield—that is killing pedestrians.