By Rayla Bellis, SSTI
The Florida Department of Transportation plans to lower speed limits and design speeds in some areas from their current 40-45 mph limit to a 25 mph limit to improve roadway safety. They will start with a pilot program in the Tampa Bay region. This makes FDOT one of the first states to tackle head-on the safety impacts of vehicle speeds.
Speed is one of the most significant factors in roadway crashes and fatalities in the U.S., and an especially serious problem for pedestrians and bicyclists. A 2011 study conducted by the AAA Foundation for Traffic Safety found that nine out of 10 pedestrians survive a crash with a car going 20 mph. However, only five out of 10 pedestrians survive when hit at 30 mph, and just one in 10 survive when hit at least 40 mph.
FDOT has been working to improve conditions for people walking and biking since 2014 through the department’s Complete Streets implementation initiative, which aims to address the state’s ongoing pedestrian danger epidemic. FDOT is also considering other strategies for reducing vehicle speeds, including reducing lane widths to 10 feet in some urban areas. The department will be finalizing its plans later this year based on feedback submitted by stakeholders in response to the department’s draft FDOT Design Manual and new draft Complete Streets Handbook.
FDOT’s government liaison administrator Stephen Benson noted, “When people drive slower, it improves safety. If we don’t design roads like a highway, they won’t drive on the roads like a highway.”
Other states may soon follow FDOT’s lead. The National Transportation Safety Board released a studyon July 25 linking speeding to 112,580 highway crash fatalities between 2005-2014, roughly equal to the number who died in alcohol-involved crashes over the same period.
“Substantial reductions in highway crashes cannot be achieved without a renewed emphasis on the impact of speeding,” said NTSB Director of Research and Engineering Jim Ritter. “Lowering speeding-related highway deaths requires more effective use of countermeasures to prevent these crashes.”
NTSB presented recommendations from the study at a recent board meeting, including a recommendation that FHWA replace the current 85th percentile rule for determining speed limits with guidelines proven to improve safety. The NTSB study notes, “Raising speed limits to match the 85th percentile speed can result in unintended consequences. It may lead to higher operating speeds, and thus a higher 85th percentile speed. In general, there is not strong evidence that the 85th percentile speed within a given traffic flow equates to the speed with the lowest crash involvement rate for all road types.”
NTSB also noted that while speeding is one of the most common factors in motor vehicle crashes in the US, it is an underappreciated problem. The public is less aware of the risks of speeding compared with other risky driving behaviors, and it doesn’t carry the same social stigma as drunk and distracted driving.
NTBS hopes to change this perception by bringing the results of their study into the spotlight. “The simple truth is that speeding makes a crash more likely. In a crash that’s speeding related, you’re more likely to be injured, your injuries are more likely to be severe, and you’re more likely to die,” NTSB Acting Chairman Robert L. Sumwalt said in his statement at the board meeting. “And that’s true whether you’re the speeding driver, another driver, a passenger, a bicyclist, or a pedestrian.”
Rayla Bellis is a Program Manager at SSTI.
Autonomous vehicle technology has been touted as a boon to safety, avoiding or mitigating the majority of crashes that are due to human error. Now a new report attempts to put numbers to how many pedestrian crashes could have been avoided or mitigated, and the value of avoidance.
In 2012 the U.S. saw about 4,800 pedestrian fatalities involving traffic crashes; on average, a pedestrian was killed every two hours and injured every seven minutes in traffic crashes. In 2015, fatality numbers rose to 5,376 deaths. As the frequency of traffic fatalities overall has decreased over the last 10 years, the proportion of those fatalities that are pedestrians continues to slowly increase (Figure 1). With the emergence of autonomous vehicle technology, how will these numbers be impacted?The Volpe National Transportation Systems Center, in support of the National Highway Traffic Safety Administration, developed and tested a methodology to estimate potential safety benefits of pedestrian crash avoidance/mitigation (PCAM) systems. PCAM systems are installed on vehicles and use detection technologies to prevent collisions with pedestrians by warning drivers, warning pedestrians, braking the vehicle, and/or steering the vehicle. Volpe utilized two national crash databases to gather historic crash data from 2011 to 2012. Under computer-simulated conditions, Volpe tested three different manufacturer’s PCAM systems to determine if they would have aided the vehicles enough to avoid or mitigate the crash.
Volpe’s simulations focused on two types of vehicle-pedestrian crashes: 1) a vehicle going straight and a pedestrian crossing in front of it, 2) a vehicle going straight and a pedestrian walking with/against the traffic, or standing in/adjacent to the road. When pedestrians crossed in front of the vehicle, PCAM systems avoided 7 to 77 percent of crashes using automatic emergency breaks (AEB). When pedestrians were walking along traffic or standing next to the roadway, 27 to 86 percent of crashes were avoided using AEB. The wide range of system effectiveness values was due to variations caused by technology differences in each manufacturer’s PCAM systems, in addition to differences among the two databases of historical crashes. On average, the simulations revealed that the PCAM systems avoided an average of 37 percent of crashes where a pedestrian crossed in front of the vehicle and 57 percent of crashes with pedestrians on the roadside.
Based on successful crash avoidances during simulations, the report estimates that from 2011 to 2012, PCAM systems would have saved up to $8.236 billion in comprehensive costs, including 901 lives valued at $9.146 million each. In addition, these statistics only include crashes that were avoided, and significantly rise when crashes that were mitigated are included.
PCAM systems research will play a vital role in the future as more autonomous vehicles enter our roadways. The ability of researchers to improve such technologies will increase with new vehicle crash reporting regulations by NHTSA that set future crash reporting guidelines for law enforcement and other authorities.
Logan Dredske is a Project Assistant at SSTI.