Transportation Systems Software – Reliable and Resilient

by Tracy Zafian, Research Fellow

A research team led by Dr. Lance Fiondella, UMTC Research Affiliate, and professor at UMass Dartmouth, studies software reliability related to various transportation systems; and has developed a quantitative approach to assess the dynamic vulnerability of transportation networks.

lance
In September 2017, flights for many airlines worldwide were temporary disrupted when the check-in system software experienced a network glitch. (Mike Schuh/Twitter)

The role of computers in operating, optimizing, and securing transportation networks and systems has grown tremendously in the last few decades. Onboard computers help run, sometimes autonomously, individual vehicles for land, sea, and air. On a larger scale, computers assist with the monitoring of traffic and transportation infrastructure to help transportation networks operate safely and efficiently.

Unfortunately, the computers performing such tasks do not always run as intended. For example, in September 2017, the New York Times described how air travel was temporarily delayed at airports on at least four continents when airline software that manages customer reservations and check-ins for close to 200 airlines worldwide experienced network glitches. In another example, in February 2018, traffic signal lights for an estimated 600 intersections in New York City failed to work properly after a “routine software upgrade” was carried out overnight. CBS news reported that some signal lights became flashing red lights and others went completely dark. Drivers, pedestrians, and others traveling through those intersections needed to exercise extra caution until the impacted traffic lights were fixed; over 99% of the lights were fixed within 18 hours.

Dr. Lance Fiondella, UMTC Research Affiliate and a professor at UMass Dartmouth in the Department of Electrical and Computer Engineering, conducts research on software reliability engineering, and transportation. The American National Standards Institute defines software reliability as the probability of failure-free operation for a certain amount of time in a certain environment. Unlike hardware, software does not fail due to physical flaws and wear, but due to design flaws, which as described in the Handbook of Software Reliability Engineering (Michael Lyu, editor), can be harder than hardware flaws to visualize, detect, and correct.

Dr. Fiondella and his Ph.D. student Vidhyashree Nagaraju authored a chapter in the recently published Handbook of RAMS in Railway Systems: Theory and Practice. RAMS stands for Reliability, Availability, Maintainability, and Safety, and Fiondella and their chapter focused on software reliability in RAMS management. As the chapter describes, “In the context of railway systems, software reliability is important in critical applications such as dynamic control of safe separation between trains in railway signaling, railway interlocking systems, monitoring and real-time control software, and hardware control software.” The chapter presents different software reliability models, discussing their mathematical formulation, the underlying assumptions, and procedures to fit these models to failure data obtained during testing with examples from the research literature. The chapter also provides a web link to an open source software failure and reliability tool created at Fiondella’s lab that implements many of the concepts discussed in the chapter.

Dr. Fiondella and his team have also developed a quantitative approach to assess the dynamic vulnerability of transportation networks. The approach uses methods from traffic simulation and incorporates traffic demand and congestion changes as a function of time, including the peaks in traffic volumes by time of day and for community activities such as large sporting events or other gatherings. Fiondella and his students, including lead author Ph.D. student Venkateswaran Shekar, presented a research paper describing this approach at the 2017 IEEE (Institute of Electrical and Electronics Engineers) Symposium on Technologies for Homeland Security, along with a series of examples. The paper stated that “this approach can quantify the time-varying criticality of [network] links, which can inform network defense and resilience planning. Because pervasive deployment of defenses is prohibitively expensive, identifying how the vulnerability of links changes over time will provide greater insight, enabling quantitative assessment of competing for defense strategies to preserve continuity of travel time reliability within a transportation network despite disruptions.”

Fiondella is currently part of a MassDOT sponsored project, multi-campus (Lowell, Dartmouth, and Amherst) UMass research team studying the use of unmanned aerial systems (UASs, commonly referred to as drones) for surface transportation applications. This study is being sponsored by MassDOT.  Fiondella’s project task includes researchers from UMass Dartmouth and UMass Lowell and focuses on the security of UAS systems and data. As described in the study proposal, “there is an urgent need to ensure that UASs are engineered with sufficient security to withstand and recover from inevitable cyber-attacks.” The researchers are conducting a detailed literature search and synthesis on state-of-the-art secure UAS engineering techniques including compliance with national and international standards. The results from this work and the other project tasks will be used to help develop a pilot program for using UASs at MassDOT.

Fiondella recently received a prestigious National Science Foundation CAREER Award and multi-year grant for his research on Software Reliability and Security Assessment: Modeling and Algorithms.

 

Safety with a Rumble

by Matt Mann, Research Program Coordinator

Centerline rumble strips have been shown to reduce lane departure crashes by as much as 25% on rural roads, and are now being installed on undivided, rural, two-lane highways in Massachusetts as appropriate.

rumble
The sinusoidal rumble strip uses a wave-shaped rumble strip to create the noise and vibration necessary to alert the driver. (Road and Bridges, 4/3/2017)

Improving safety, at a low-cost, can reduce crashes and save lives. In the U.S., 60% of crashes on rural roads result in a fatality. Of these fatal crashes, approximately 90% are on two-lane roads. Lane departure crashes from vehicles crossing over the centerline on undivided, two-lane, rural roads have been proven to decrease with the installation of centerline rumble strips (CLRS). This reduction can be as high as 25% along certain rural roads, and even higher when CLRS are installed along with shoulder rumble strips (SRS).

Many factors contribute to drivers crossing over the center yellow line, including speeding, fatigue, and drowsiness, and distracted driving. Some common techniques on the roads now that try to mitigate lane departures and improve safety include, but are not limited to centerline and edge line pavement lane markings, higher retroreflectivity of traffic signs (for day and nighttime visibility), and vertical reflective panels. All of these have had some success. A number of studies, however, have shown CLRS to be more effective along certain rural sections of highways, in decreasing lane departures.

The purpose of CLRS is to prevent vehicles from crashing head-on or sideswiping each other. Vehicles tend to veer outside of their lane on all types of roadways, especially on undivided, two-lane rural highways where cross-over crashes are most common. CLRS can also act as a traffic calming tool. Similar in design to the rumble strips on the shoulders of Interstates and other limited access highways, CLRS are located along the centerline. With either placement, the objective of the rumble strips is to alert inattentive drivers that they are veering outside of their lane, and ideally help them correct this action before a crash occurs.

The main reason for CLRS’ effectiveness is their design, specifically the vibrations and noise when tires cross over them. However, this noise has also been a major reason why CLRS are not used on more roads. Abutters and businesses have complained about CLRS being too loud as vehicles cross over them. California Department of Transportation (CalTrans) and Minnesota DOT (MnDOT) have conducted research on creating effective, quieter CLRS. MnDOT has developed the sinusoidal wave-shaped rumble strip. Some study results have shown a decrease in noise levels outside the vehicle, as vehicles cross over these sinusoidal rumble strips, while the CLRS still maintain the effectiveness by alerting drivers of lane departures. In addition to noise, another concern of CLRS is the potential reduction of visibility of the centerline yellow strip, though, in a survey by the Insurance Institute for Highway Safety, some respondents reported that the visibility of the centerline yellow strip in the rain was better over CLRS than on flat pavement.

MassDOT, along with other DOTs, continues to develop and implement CLRS on their rural, undivided, two-lane highways. MassDOT currently considers implementing CLRS on an as needed basis. Decisions about where to install CLRS are based on a couple of variables, including lane departure crash data and land use (regarding the noise factor). As discussed with Bonnie Polin, MassDOT Highway Division Manager of Highway Safety, CLRS were recently included in a paving project along sections of Route 140 in Gardner and Winchendon. CLRS are easier and more cost effective to install when a roadway is being re-paved as was the case along Route 140. As MassDOT updates its Strategic Highway Safety Plan, CLRS are referenced as a safety measure to prevent lane departures.  MassDOT will continue to support and install CLRS on their secondary roads, where appropriate.

 

 

Listening Session on Transit, and Active Transportation, and Mobility – A Recap

by Tracy Zafian, Research Fellow

UMass Amherst faculty and UMTC Research Affiliates Dr. Song Gao and Dr. Eric Gonzales presented at the Governor’s Commission on the Future of Transportation listening session on transit, active transportation, and mobility.

FoT
From left: UMass Amherst Professors Eric Gonzales and Song Gao talk with Secretary of Transportation Stephanie Pollack and members of the Commission on the Future of Transportation at the Commission’s listening session at UMass Lowell. (UMTC)

In June, Governor Baker’s Commission on the Future of Transportation in Massachusetts held a listening session to discuss transit, active transportation, and mobility in Massachusetts. This session, at UMass Lowell, was the third of the Commission’s five listening sessions around the state. Each session focused on different transportation topics as the Commission gathered ideas, information and public comment that it will then incorporate into a report with recommendations for transportation investments and policies in Massachusetts for the 2020-2040 period. The report will be sent to the Governor by December 2018.

As with the other listening sessions, this session included brief presentations by UMass researchers followed by an open comment period during which members of the public could offer their suggestions and feedback on the session topic or on future transportation in Massachusetts more generally. Recording of the listening sessions can be viewed on the Commission’s website (direct link to the third session here).

Two UMTC Research Affiliates, UMass Amherst professors Song Gao and Eric Gonzales, presented at this listening session. Gonzales opened his remarks by discussing that when thinking about transit services, it’s important to not only consider specific routes and schedules, but the larger picture of the benefits individuals and society can receive with transit services, including increased mobility and efficiency, cost-effectiveness, and reduced environmental impacts. He noted too that active transportation modes, such as walking and biking, can also achieve these same benefits. Gonzales then briefly reviewed the history of transportation infrastructure in Massachusetts, including highways and the MBTA subway system, noting how investments in infrastructure can have impacts long beyond the 20-year time horizon on which the Commission is focusing, and should be considered in that context.

Gonzales also spoke about transit’s important role as “a tool for social equity and for inclusion, providing mobility to people across the socioeconomic spectrum, age, and physical ability.” He mentioned challenges for transit, including providing bus access in spread-out rural and suburban areas, but also opportunities. These opportunities could include public-private partnerships, for example, between transit agencies and ridesharing companies such as Lyft and Uber. The MBTA is currently conducting a pilot project under which MBTA paratransit customers can take get rides through Uber or Lyft as an alternative to traditional paratransit vans, to help serve these customers’ needs better; Gonzales led a MassDOT-funded study to evaluate the pilot project. There are also opportunities for more integrated services with the use of technology, where the different travel modes for trips can be better connected and accessed, for example, through a smartphone app that integrates bus, ride-share, and bike-share access and user payments. Gonzales mentioned that Helsinki, Finland has been working on such an integrated transportation service system.  A recent Governing magazine article discussed the push for more seamless urban mobility in Helsinki, and similar efforts underway in the U.S.

Professor Gao’s presentation followed Gonzales’ and focused on the demand for transportation services and how this demand can be better managed. For someone traveling between an origin and a destination, Gao asked questions such as: are there alternatives to making this trip, is there flexibility on when the trip occurs – for example, what time of day – and what different travel modes are feasible for this trip and this particular traveler. Gao discussed how transportation policies and pricing can shape transportation demand and people’s decisions about when and how they travel, and if there are some trips they will not take at all. Some states are using higher pricing, also referred to as congestion pricing, to deter single-occupancy vehicles from traveling during the peak times. Gao said that one concern about congestion pricing is the equity impacts since low-income people are more adversely impacted by travel cost increases than are higher-income people.

Another approach for impacting travel demand is rewarding people who make more energy-efficient travel choices, for example, deciding to use transit or bicycle to work instead of driving, or who commute at off-peak hours. Gao mentioned a study from the Netherlands that provided participants with daily monetary and other (smartphone credits) rewards to encourage them to avoid driving during the morning rush hour. The study found that 30-40% of participants changed their behavior as a result of these incentives. Gao also discussed a study that she, and colleagues at UMass Amherst and at the Massachusetts Institute of Technology, are conducting to develop a smartphone app to provide up-to-date travel information and incentivize people to change their travel choices to conserve energy. The app, for the Boston metro area, will use real and simulated personal travel data to reward people who change their departure times, routes, modes, or vehicles based on the app’s real-time data, and thereby reduce their energy consumption. The rewards based on energy savings will be able to be redeemed at local participating vendors. Data from preliminary testing of the app show positive results in terms of reducing energy use and travel times.

During the comment period following the presentations, a number of the commenters talked about the importance of having good infrastructure for biking and walking and better connections between modes. There was also discussion about the need to provide transportation options for the “last mile” section of trips, between where fixed-route transit services end and people’s final destinations. Ridesharing companies, also known as Transportation Network Companies (TNCs) can help with those gaps.  A number of the speakers encouraged the creation of more public-private partnerships to help with last-mile service and for addressing the transportation needs of those populations, such as the elderly, disabled, and low-income, who are often underserved by current transportation options and infrastructure. Professor Gao raised the point that there are great opportunities for partnership between public transit and TNCs, but that the goals of TNCs may not always be aligned with public goals since private companies are usually seeking to maximize their profits.

Improving Safety in the Work Zone

by Courtney Murtagh, Intern, and Tracy Zafian, Research Fellow

In 2015, 860 vehicle crashes in roadway work zones were reported in Massachusetts, and over 96,000 crashes in work zones nationwide. Researchers and state officials have been examining the causes, and options for reducing work zone crashes, injuries, and fatalities.

wokzone
Work zone area on the MassPike during the removal of toll booths. (Boston Herald, photo credit Angela Rowlings)

With summer in full swing, we find ourselves in the midst of another road infrastructure improvement and repair season. Drivers may have noticed an increase in the number of work zones along state and town highways in Massachusetts. During these warmer months, drivers need to take extra precautions for their safety and the safety of road construction workers.

The Federal Highway Administration (FHWA) recorded a total of 765 work zone traffic fatalities nationwide in 2016, in the Fatality Analysis and Recording System (FARS). This is a 7% increase from 2015.  Many of these fatalities (83%) were of motor vehicle drivers or passengers, the remainder were pedestrians, bicyclists, and other non-motorists. Relatedly, the U.S. Bureau of Labor Statistics found that there were 143 deaths of road workers at construction sites. This count overlaps with the FARS figures. Forty percent of the traffic fatalities in work zones are from rear-end collisions, as vehicles fail to slow down adequately approaching and traveling through the work zones.

According to the FHWA, there were 96,626 crashes in work zones in 2015, a 42% increase since 2013. The same study showed that nationwide there were on average 70 work zone traffic crashes with injury per day that year.

For Massachusetts, the State Police reported 860 work zone crashes for 2015. The data show that work zone crashes occur most often between May and September, during the day, and on a Tuesday, Wednesday or Thursday. Drivers should be especially cautious and attentive when traveling through work zones, as construction workers may be present and as drivers may be asked to stop.

Speed limits in work zones are set according to state law. The law allows for the doubling of speeding fines in work zone areas.

In 2016, MassDOT created a Work Zone Safety Task Force to consider innovative engineering and technology-related solutions for better work zone safety. The Work Zone Task Force implemented some new safety features in work zones in 2017, including portable rumble strips, and flashing blue LED lights in work zones to simulate a police presence and get drivers to reduce their speed. Another type of technology being considered are smart cones, which communicate with construction workers to warn them when potential threats, such as a speeding or erratically driving vehicle, are approaching a work zone. A previous Innovative Outlook article discussed some of the technology options for improved work zone safety in more detail.

Another potential way to reduce work zone crashes is the ‘zipper’ merge. The zipper occurs when two lanes of traffic equally merge into one. Research conducted at UMass Amherst by Dr. Michael Knodler and Civil Engineering graduate students Alyssa Ryan and Francis Tainter has been investigating the potential use of zipper merges to help improve traffic safety. UMass Amherst’s zipper merge research was discussed in the March and April 2018 Innovative Outlook. An FHWA analysis of FARS crash fatality data found improper merging to be the second most dangerous driving maneuver, behind only inattentive driving. The zipper merge is hypothesized to improve both roadway safety and efficiency, including in work zone areas.

Massachusetts is Meeting Climate Change Head On

by Matt Mann, Reseach Program Coordinator

climateboston
State Street, Boston – City Lab

As weather events become more extreme, MassDOT and Massachusetts communities, especially those on the coast, recognize their infrastructure is vulnerable. Coastal cities and towns are currently grappling with the extreme climate impacts of higher temperatures, increased extreme precipitation and greater amounts of sea level rise. All of these impacts are not new, they have slowly been occurring over the past century.  It is predicted these changes will accelerate and increases will happen over a shorter length of time (e.g. by 2030, the sea level could rise by 4”-8” (BRAG Report, 2016)).

MassDOT and Climate Ready Boston presented at the April 2018 MassDOT Innovation and Mobility Exchange on the impacts to transportation assets and infrastructure, and strategies to better accommodate climate change. Mia Mansfield, Climate Ready Boston, presented on goals to guide Boston’s future growth:

  • Goal 1: Provide quality of life in accessible neighborhoods
  • Goal 2: Drive inclusive economic growth
  • Goal 3: Promote a healthy environment and adapt to climate change, and
  • Goal 4: Invest in infrastructure, open space and culture

Associated with these goals are planning and implementation projects for creating resilient infrastructure and buildings, preparing communities, and protecting shorelines. The feedback from the public outreach on what types of flood ready improvements the public would like to see included expanding open space, berm development, and flood walls. Project areas Climate Ready Boston has focused on are East Boston, Charlestown, and South Boston. Mansfield spoke about this initiative saying, “The resiliency strategy embraces layered flood control and integrated green infrastructure measures that mitigate the effects of climate change, and create social, environmental, and economic benefits and value to the people of East Boston and Charlestown and to all who share in the health of the city and the harbor.”

The existing transportation assets will be impacted by more flash floods, landslides, and flooding. Further, increased precipitation could have adverse impacts on the infrastructure that helps move the water, especially on culverts. Hongyan Oliver, MassDOT Office of Transportation Planning, and Chris Dorney, WSP USA, presented on MassDOT’s multi-year statewide Climate Adaptation Vulnerability Assessment study. This study aims first to identify a prioritized set of MassDOT transportation assets throughout the Commonwealth that is at high risk for future inland flooding, and second to provide actionable scientific information for adaptive strategies, and future capital and project planning. This second goal begins on a broader planning level and then is developed through a detailed analysis of vulnerable assets. One challenge is mapping statewide future floodplains where vulnerable assets are located. With this challenge in mind, MassDOT is currently conducting a pilot mapping study on a watershed in western Massachusetts. The approach is to prepare georeferenced data, assign slopes, calculate current peak flows and 100-year flows, elevations, and floodplains, and evaluate the asset exposure. Procedures for floodplain mapping will include developing an instruction manual, applying the data management protocol, and automating parts of the process for efficiency.

Next steps after that will include training additional MassDOT staff on the procedures, and applying the pilot study procedures and lessons learned from all other watersheds in the state and sharing the results and data with stakeholders.  Eventually, this important information and these strategies can then be incorporated into MassDOT’s project prioritization, capital planning, asset management system, and emergency preparedness procedures.

Prospects and Challenges for Automated and Autonomous Vehicles

by Tracy Zafian, Research Fellow

avcrash
May 2018: A car driven with Tesla’s Autopilot driver assist system crashed into a parked police car. The Autopilot system is designed to be used on limited access highways, not on roadways such as this one. (Source: Uncredited/AP/Rex/Shutterstock)

In March 2018, an Uber Volvo operating in automated driving mode, with a driver at the wheel, hit and killed a pedestrian in Arizona. It was the first autonomous vehicle (AV)-related pedestrian fatality. There have been other crashes involving autonomous test vehicles and additional fatalities involving lower-level automated vehicles since.  Also in March, a driver in California was killed when his Tesla, in autopilot mode, crashed into a concrete highway lane divider and caught fire. Last month, a Tesla, in autopilot mode, crashed into a parked firetruck in Utah and into a parked police car in California.  Injuries were minor in these instances.

All of these crashes have occurred while there has been a driver at the wheel making decisions about when to use and disengage the automated driving assist system. As reported in a USA Today article, following the Utah firetruck crash, Tesla issued a statement saying, “When using Autopilot, drivers are continuously reminded of their responsibility to keep their hands on the wheel and maintain control of the vehicle at all time,” and, “Autopilot is designed for use on highways that have a center divider and clear lane markings.” These conditions are not always met when crashes occur; for example, the driver in the Utah crash admitted to being distracted by their phone before the crash. From the National Transportation Safety Board’s preliminary findings from investigating the Uber pedestrian crash, there was no warning given to the safety driver before the crash. Current AV technologies, such as Tesla’s Autopilot, are referred to by car manufacturers as “driver assistance systems” but it is not clear that all drivers understand their limitations, including the need for drivers to monitor the driving environment and stay involved in the driving process.

The Society of Automotive Engineers has developed a classification system for autonomous vehicles. The classification includes six levels (Level 0-5); with Level 5 being fully autonomous and Level 1, containing some automated features such as adaptive cruise control and parking assist. Most current automated driver assistance systems are Level 1 or 2, meaning that drivers still need to be actively involved.

Driver assistance systems and autonomous vehicles hold great promise for improving safety and mobility, but AV technologies are still relatively new, and numerous challenges remain. A number of universities and researchers in Massachusetts are exploring this topic. In April, a commentary by MIT AgeLab researchers, “People must retain control of autonomous vehicles,” was published in Nature magazine (link is for the article). In their remarks, Dr. Ashley Nune, Dr. Bryan Reimer, and Dr. Joseph Coughlin, Age Lab Director and UMass Transportation Center Research (UMTC) Affiliate, focused on two areas – safety and liability – that need urgent attention as policies and regulations are developed for autonomous and semi-autonomous vehicles. They write that, in their view, “some form of human intervention will always be required. Driverless cars should be treated much like aircraft, in which the involvement of people is required despite such systems being highly automated. Current testing of autonomous vehicles abides by this principle. Safety drivers are present, even though developers and regulators talk of full automation.” The researchers’ piece ends with key points for policymakers preparing AV legislation to consider:

  • Driverless does not, and should not, mean without a human operator
  • More information should be shared with operators/drivers about how well different autonomous and driver assist systems are working, including their reliability and limitations
  • Operators should need to demonstrate that they understand the autonomous and driver assist systems in their vehicles and should be tested on their understanding and competence at periodic intervals
  • Remote monitoring networks should be established and shift time guidelines considered for workers monitoring AVs.

In May, a forum held at Harvard University’s T.H. Chan School of Public Health on “Self-Driving Cars: Pros and Cons for the Public’s Health.” (A recording of this session and a transcript are available at this link.) Dr. Jay Winsten, Associate Dean for Health Communication at Harvard, said there is hope right now around the potential for autonomous and highly automated vehicles to reduce traffic deaths.  He also addressed the hype around this: “I think both the media and some of the manufacturers and developers have been going a little too far in setting public expectations for what to expect, especially in the short-term and in the medium-term.” The panelists discussed that initially most vehicles will be highly automated (SAE Level 2), not autonomous (Level 3-5), and the deployment of the autonomous vehicles is likely to occur first for long-distance, highway-based commercial transport and in urban areas for shuttles and other short-distance trips. There are some challenges including the current reliability and drivers’ understanding of AV technologies, including the need for drivers to stay alert while behind the wheel and the safety of vulnerable road users. There are also concerns regarding regulation. The federal government through the National Highway Safety Administration has developed some guidelines regarding autonomous vehicles and automated driving systems. However, there are currently no federal regulations in place regarding autonomous vehicles. Therefore, currently regulations are primarily set at the state level.

As described in an earlier Innovative Outlook article, Governor Baker and Massachusetts state officials have largely taken the approach that it is better not to regulate AVs through legislation, as the technologies are still evolving and legislation can be difficult to modify once passed. Panelist Deborah Hersman of the National Safety Council, shared those concerns, saying “We’ve got to find out how to do this differently” so that any regulations keep up with changing technology. Herman also urged there be more transparency and data sharing regarding specific AV technologies and how well they perform, saying that NTSB investigations after a crash can be challenged by lack of access to such data.

In June 2018, MassDOT entered into a Memorandum of Understanding with several municipalities to help facilitate and expand autonomous vehicle testing on roadways in Massachusetts. As described in a MassDOT blog article, “Following the signing of this MOU, MassDOT and the participating communities will finalize a universal application for companies to use when seeking to test autonomous vehicles and the participating municipalities will identify locations and roadways suitable for autonomous vehicle testing. ‘This agreement will allow companies to responsibly develop and test autonomous vehicle technology in Massachusetts, while ensuring there are uniform safety guidelines in place,’ said Governor Baker [at the MOU signing] . ‘The MOU builds on the existing autonomous vehicle testing framework while simplifying the process for municipalities to work with innovative companies that are seeking to advance transportation, create jobs in our nation leading innovation economy, and improve our quality of life in the Commonwealth.’  …Said Lieutenant Governor Karyn Polito, ‘By creating a standardized process and working collectively with local officials, we can generate economic growth and support our communities as they play a role in the future of innovation and motor vehicle automation.’ Fourteen communities signed the MOU initially, including Boston, Worcester, Arlington, Boston, Braintree, Brookline, Cambridge, Chelse, Medford, Melrose, Newton, Revere, Somerville, Weymouth, Winthrop, and Worcester.  In addition, the Massachusetts Department of Conservation and Recreation also joined the MOU, allowing Commonwealth-owned parkways to be available for autonomous vehicle testing.

 

 

Safety for Older Drivers

by Tracy Zafian, Research Fellow

older2
AAA has estimated that by 2030, there will be more than 60 million people in the U.S. age 65 & over licensed to drive. (Photo source: IIHS.org, credit istock.com/KLH49)

Most people outlive their ability to drive by seven to ten years. This important statistic from the American Automobile Association (AAA) was cited by Michele Ellicks of the Massachusetts Registry of Motor Vehicles (RMV) at the April 2018 MassDOT Innovation and Mobility Exchange, at a session on Safe Driving for Seniors and People with Disabilities.

There were more than 40 million drivers age 65 years and older in the U.S. in 2015, according to the Federal Highway Administration (FHWA). This population is expected to increase significantly in coming decades. AAA has estimated that by 2030, there will be more than 70 million people in the U.S. in this age group with approximately 85-90% of them licensed to drive. In 2016, 18% of all traffic-related fatalities in the U.S. involved people age 65 and older. In Massachusetts, 16% (133) of all traffic fatalities in the state involved people age 65 and older. Over half (54%) of those fatalities were for those age 65 to 74; the other 46% were for those age 75 and older.

Nationally, the fatality rates per 100,000 people are higher for males than females and generally higher for people age 80 and over than for those 65-79 (see chart below). The death rates increase with age because older people have more physically frail and are more likely to die from injury, as found in this study from John Hopkins School of Medicine. Older drivers are also more likely to be involved in at-fault crashes as a result of physical or cognitive impairments. The fatality rates for females fall slightly from age 80-84 to age 85 and older because females limit or cease their driving in their upper 80s more often than males.

older
Source: Insurance Institute for Highway Safety Analysis of National Highway Transportation Safety Administration (NHTSA) FARS (Fatality Analysis Reporting System) 2016 data, released December 2017. Viewed at http://www.iihs.org/iihs/topics/t/older-drivers/fatalityfacts/older-people.

Intersections can be especially difficult for older drivers to navigate. Extensive research conducted at the University of Massachusetts Amherst on driving simulators and on-road has shown that older drivers do not look as often as other drivers towards their turning direction or other vehicles when turning at T-intersections or four-way intersections. As a result, older drivers may be more likely to be involved in traffic crashes.

UMass Amherst researchers working under the supervision of Dr. Michael Knodler are currently investigating older drivers’ crashes during left-turns at signalized intersections; using data gathered from their vehicles and the drivers themselves as part of the SHRP2 (Strategic Highway Research Program 2) project to collect naturalistic driving data on over 2,300 drivers at six cities around the country. The researchers hope this study will help with understanding why and how left turns across path crashes at intersections are more likely for older drivers.

In previous older driver research conducted at UMass Amherst, Dr. Matthew Romoser conducted one study on drivers age 72 to 87 and a comparison group of drivers age 25 to 55 for his dissertation, and then a follow-up study with the older drivers as a post-doctoral researcher. Romoser’s first study, conducted with his advisor, Dr. Donald Fisher, UMass Transportation Center (UMTC) Research Affiliate and UMass Amherst Human Performance Laboratory (HPL) Director, found that the older drivers took fewer roadway glances towards potential hazards than younger drivers while turning. Romoser also found that providing active training and customized feedback regarding their driving to the older participants led to significant improvements in their glances both in a driving simulator and on-road, towards potential hazards as they approached and went through intersections. Romoser’s follow-up study, conducted two years after the first study with the same older drivers, found that those drivers who received active training in the first study still made 50% more glances towards potential hazards than they did before training two years earlier.

The benefits of training programs to help older drivers stay safe at intersections was further examined in a study by past HPL researchers Dr. Siby Samuel and Dr. Yusuke Yamani, with Dr. Fisher. This research found that training programs, such as Dr. Romoser’s, which help improve older drivers’ glance behaviors at intersections, can be effective even though they don’t address underlying declines in cognitive, visual, and motor functions for these drivers as they age. The researchers found some evidence that these training programs are effective because, through the training, drivers learn to decouple their hand, foot, and head movements at intersections, and that doing so may help reduce the impacts of cognitive, motor, and visual declines on their driving.

This research is promising and suggests that some types of training may help older adults safely continue to drive longer than they would be able to otherwise. In Massachusetts, various measures have been taken to promote older driver safety. Under state law, for drivers age 75 and over driver license renewals must be done in person and they include an eye exam. The RMV holds free workshops around the state on issues facing older drivers, including if and when an older person should give up driving.

For adults who do stop driving for safety reasons, MassMobility is a state initiative to improve the transportation options for adults who don’t have a car. The options include both traditional transportation providers such as buses and paratransit and also newer alternatives such as Uber, Lyft, and other Transportation Network Companies (TNCs). A number of sessions at this year’s Innovative and Mobility Exchange discussed alternatives for meeting transportation needs for this population. Options included using TNCs to provide rides outside of regular bus service hours and TNCs partnering with senior centers and other agencies to offer rides to people who otherwise might not be able to access (because they don’t have a smartphone or credit card) services from companies such as Uber and Lyft.

Dr. Nina Silverstein, UMTC Affiliate and Professor of Gerontology at UMass-Boston, recently co-authored a book, Introduction to Senior Transportation: Enhancing Community Mobility and Transportation Services (2018). The book provides an overview of the mobility needs of older adults and the “transportation methods that do and do not currently meet the needs and wants of senior passengers.”

Around and Around for Pedestrian and Cyclist Safety

by Tracy Zafian, Research Fellow, and Courtney Murtagh, UMTC Intern

round2
Bicycle in Roundabout (Source: bikewalkencinitas.org)

Roundabouts were introduced to America’s traffic system as a way to increase traffic safety and support greater traffic volumes without extensive new construction. A roundabout’s circular formation works by making incoming vehicles yield to circulating and exiting traffic. This allows cars to maintain a steady traffic flow through the intersection and not have to come to a complete stop. Roundabouts have been proven to be able to handle up to 50 percent more traffic compared to traditional intersections that use traffic signals or stop signs. Further, due to vehicles’ reduced speeds at roundabouts, crash and injury rates can significantly decrease, especially for motorists. According to the Insurance Institute on Highway Safety (IIHS), studies of U.S. intersections that have switched from stop signs or traffic signals to roundabouts have found a decrease in all traffic crashes of 35-47% and a reduction of injury crashes of 72-80%. The IIHS importantly notes that the U.S. studies have focused primarily on single-lane roundabouts. When included in research studies, two-lane roundabouts have been shown to have smaller reductions in crashes compared with single-lane roundabouts or even with increases in crashes. Crashes at roundabouts have also involved bicycle and pedestrians. Non-motorized road users, such as bicyclists and pedestrians, can face several safety and technical challenges when traveling through roundabouts. These challenges can lead to greater crash risk at roundabouts.  Dr. Eleni Christofa, UMTC Affiliate Researcher Civil Engineering and Professor Aura Ganz of Electric and Computer Engineering from UMass Amherst are studying the safety of visually impaired pedestrians at roundabouts. Visually impaired pedestrians may be used to having auditory cues from traffic and signals at intersections to know when it’s safe to cross. Roundabouts, designed with continuous traffic flow in mind, may not have such cues. Additionally, it can be difficult for drivers to detect pedestrians at a crosswalk while the driver is focused on navigating a roundabout.  Dr. Christofa and Dr. Ganz have developed a new dynamic warning sign to alert drivers entering a roundabout as to where pedestrians are attempting to cross. This sign contains a symbolic traffic circle and symbolic crosswalks for each approach of the roundabout. If a pedestrian is about to cross one of the roundabout’s approaches, they can activate the sign which will then flash to alert drivers where pedestrians are crossing in the roundabout. This is designed to help both with driver awareness of pedestrians and pedestrian safety. The dynamic warning sign will be tested on the UMass Amherst advanced driving simulator this summer. If the sign works as expected, it could be used to help with the safety of pedestrians at roundabouts generally and particularly for the visually impaired and those with mobility impairments who take longer in crosswalks.

 

round
Proposed dynamic warning sign for pedestrian crossings at roundabouts. Pedestrians activate the sign to flash and show where they are crossing to help alert drivers traversing the roundabout to their presence.

One of Dr. Christofa’ s graduate students, Derek Roach, conducted other research on roundabouts for his Master’s thesis. His study looked at the impact of roundabouts from a driver behavior, vehicle emissions, and safety perspective. As part of his research, Roach reviewed other studies that examined the safety of bicyclists and pedestrians at roundabouts. One of these studies found that drivers who are exiting a roundabout are less likely to yield to pedestrians than when the drivers enter the roundabout.  This same study found that as speed increases in roundabouts, drivers are less likely to yield for pedestrians, making it harder and less safe for pedestrians to cross.

In terms of bicyclist safety, Roach examined a number of studies by researcher Stijn Daniels and colleagues in Belgium. Daniels’ work has found increases in the number of bicyclist crashes and in crash severity when intersections are replaced with roundabouts. Other studies have reported potential explanations for these increases. One study, by researcher Bob Cumming in Australia, found that a contributing factor of bicyclist crashes in one lane roundabouts was bicyclists staying very close to the right curb while going through the roundabout, which would lead motorists to try and pass them in the roundabout. In these cases, it is safer for bicyclists to take the main travel lane instead of being so close to the curb.

At the MassDOT’s 2017 Innovation and Tech Transfer Exchange, presenters from Kittelson and Associates gave an overview on bicycles at roundabouts, including a review of bicycle facility design standards and practices in Massachusetts and elsewhere. Each of the MassDOT Highway Districts in the state has at least one roundabout. MassDOT’s guidance for roundabouts gives special attention to rotary retrofits, building roundabouts in constrained environments, and incorporating state-of-the-practice bicycle and pedestrian design into roundabouts. One important current practice is to treat low-traffic volume and high-traffic volume roundabouts differently, to support bicyclist safety. For lower traffic roundabouts, bicycles are encouraged to circulate with motor vehicles. For higher traffic roundabouts, it is encouraged for bicycles to have a protected intersection with a separate bicycle path, and for bicyclists to have the option of either going through the intersection as a vehicle or pedestrian.

Hot Mix Asphalt Mixtures – What Works

by Courtney Murtagh, UMTC Intern, and Tracy Zafian, Research Fellow

wallapic
Road paving project in Lee, MA, 2010. (Source: blog.mass.gov).

Dr. Walaa Mogawer, UMTC Research Affiliate, Professor at UMass-Dartmouth, and UMass-Dartmouth Research Engineer Alexander Austerman recently published the results of their research study on Experimental Hot Mix Asphalt Projects Placed in Massachusetts. Professor Mogawer discussed this research topic in an Innovative Outlook interview in September 2017.

The study’s primary goal was to monitor roadway projects in the Commonwealth that used different experimental mixtures of asphalt to see which mixtures worked best, with the longest service life, best distress resistance, and easiest placement or construction. As described in the study report, the data gathered through this study can aid “Massachusetts in determining if full-scale implementation of these design methodologies and technologies is cost-effective in the long term. Overall, it is anticipated that well-performing technologies could be separated from poor-performing ones, thus leading to better decisions for future infrastructure.”

This study, conducted over a 5-year period (2012-2017), evaluated the performance of experimental hot mix asphalt (HMA) mixtures used in 12 different road pavement projects around Massachusetts. The 12 projects selected by MassDOT staff for this evaluation each involved new pavement technologies or new specifications. These technologies and specifications were tried for a variety of reasons, ranging from trying to mitigate reflective cracks in HMA layers placed over plain concrete slabs to the construction of environmentally friendly “green roads” by the incorporation of warm mix asphalt and ground tire rubber.

As described in the report, at the start of the study the researchers worked to collect all available data from MassDOT on each of the selected projects, including “all bid contract documents, material specifications, plant reports, construction quality assurance data, ride quality and distress data.”

The study then involved developing monitoring plans for each selected project, some of which had been constructed prior to the study. For each site, condition data were collected periodically throughout the duration of the study to quantify the performance of each mix and the changes in performance over time. Data were collected in the same manner for each project, using standardized techniques from MassDOT’s Pavement Management Section, such as surveying distress and calculating the relevant Pavement Condition Index (PCI). This ensured fair and consistent measurements and evaluations for each site.

The study’s primary conclusions and recommendations were as follows:

  • The condition data provided by the MassDOT Pavement Management Section provided critical data required to be able to evaluate the performance of monitored projects over an extended period of time.
  • The tested alternative technologies and specifications generally provided acceptable performance in terms of rutting, cracking and ride quality. If the projects continue to display acceptable levels of performance over time, it was suggested that final specifications be developed so that that same mixtures and strategies can be used in the future.
  • For future road paving projects involving new technologies, it was recommended that a monitoring plan be developed and implemented before the start of these projects. This would allow for a more comprehensive collection of data regarding the technologies’ performance and cost-benefit results over time and assist MassDOT in making more informed decisions when developing project specifications.

The final study report by Dr. Mogawer and Mr. Austerman can be viewed at this link.  This research was funded through the MassDOT Research Program with Federal Highway Administration (FHWA) State Planning and Research (SPR) funds.

Large Truck Crash Fatalities

by Tracy Zafian, Research Fellow

truck2
An 18-wheeler maneuvers through Worcester traffic (from Worcester Magazine, file photo, Steven King)

The Insurance Institute for Highway Safety (IIHS) has updated its summary on large truck crashes and fatalities to include 2016 data from the Fatality Analysis Reporting System (FARS) maintained by the National Highway Transportation Safety Administration (NHTSA). The FARS data show though the number of deaths from large truck crashes has decreased nationally over the last 30 years, the last few years have seen an increase.

In 2016, a total of 3,986 people died in large truck crashes. Two-thirds of these deaths were occupants of cars and other passenger vehicles, 17 percent were truck occupants, and 16 percent were pedestrians, bicyclists, or motorcyclists.

According to IIHS’s analysis of the 2016 FARS data:

  • The number of people who died in large truck crashes was 27% higher in 2016 than in 2009, when it was the lowest it had been since the collection of fatal crash data began in 1975.
  • The number of truck occupant deaths was 47% higher than in 2009.
  • 73% of deaths in large truck crashes involved tractor trailers.
  • 62% of large truck occupant deaths occurred in single-vehicle crashes.
  • 67% of large truck occupants that were killed in multiple-vehicle crashes were in a collision involving another large truck.
truck
Data from the Insurance Institute for Highway Safety, Dec 2017. http://www.iihs.org/iihs/topics/t/large-trucks/fatalityfacts/large-trucks

In its summary, the IIHS writes that “truck-braking capability can be a factor in truck crashes.  Loaded tractor-trailers take 20-40% farther than cars to stop and the discrepancy is greater on wet roads or with poorly maintained brakes.  Truck driver fatigue also is a known crash risk.”

A study conducted by NHTSA and the Federal Motor Carrier Safety Administration (FMCSA) on large truck crashes over a 3-year period found that truck driver inattention due to fatigue, distraction, and related factors can contribute up to 35% of truck crashes involved an injury or death. As discussed in a recent Innovative Outlook article, one issue which may contribute to truck driver fatigue is the lack of sufficient rest areas for large trucks.

The recent FARS data for Massachusetts shows that the number of fatal crashes in-state involving large trucks declined from 31 crashes in 2013 to 25 crashes in 2016. Over the same period, the number of truck occupant deaths from these crashes decreased from 4 to 2. This indicates that many of the people killed in the crashes involving large trucks were outside of the trucks, as occupants in other vehicles or as motorcyclists, bicyclists, or pedestrians.