Where Progress Happens! A Research Implementation Exchange

roadwithmoleculesMassDOT has been leading the charge with innovative infrastructure improvements for many years; focusing on preservation, safety, the environment and efficiency. We reached out to our One Center Research Affiliate, Dr. Walaa Mogawer, a Professor at University of Massachusetts Dartmouth and Director of the Highway Sustainability Research Center to discuss the current research in Massachusetts. Dr. Mogawer has collaborated directly with MassDOT’s pavement management section, on developing asphalt mixtures that could extend the service life of pavements and reduce costs.  We spoke with Dr. Mogawer and the Pavement Management Engineer for the Highway Division, and MassDOT Project Champion Ed Naras to discuss how this research is being implemented.  Here are some questions that were asked:

How are the results of your recent MassDOT research project being implemented in Massachusetts?

Dr. Mogawer’s most recent research entitled Field Monitoring of Experimental Hot Mix Asphalt Projects Placed in Massachusetts involved evaluating numerous field trials of experimental mixtures placed by MassDOT since 2000. Dr. Mogawer stated that, “the results of this study are a good first step in evaluating these experimental mixtures.  With this data, MassDOT can refine specifications and implement the mixtures on a broader scale.  Utilizing these mixtures will help improve the infrastructure health in Massachusetts.”

These experimental mixtures included several pilot projects using the superpave mixture design methodology, utilization of warm mix asphalt technologies, asphalt rubber mixtures, latex or polymer modified asphalt mixtures, and reflective crack relief layer mixtures. All these types of mixtures were placed to achieve a longer service life and specific outcomes in terms of performance of the pavement. A total of 12 field projects were identified for inclusion in the study. For each project, a plan was developed to monitor the experimental mixture performance using condition data (distresses, rutting, cracking, roughness, etc.) that would be measured periodically over the duration of this project.  The rehabilitation process of Massachusetts aging bridge infrastructure has been complimented by this research.

Generally, based on the monitoring plan and associated thresholds for condition indices, the experimental mixtures placed at the selected projects have provided acceptable performance in terms of cracking, rutting, and ride quality. Furthermore, the results suggest that the experimental mixtures are ready for further implementation by MassDOT.

Has this new method, practice, policy or material reduced the cost or improved safety or efficiency at MassDOT?

Speaking with Ed Naras, he indicated that the collaboration on pavement management between MassDOT and UMass Dartmouth Highway Sustainability Research Center, has been successful over the years.  Ed Naras, who works directly with Dr. Mogawer, indicated that the focus of each project is to improve the functional and structural capabilities of the roadways and bridge decks with consideration to make them more cost effective and environmentally friendly.

What are Massachusetts future priorities for implementing this research?

MassDOT will focus future research efforts on building on this work, improving paved roadway sustainability through increased recycling use, using environmentally friendly technologies, increasing pavement preservation activities, designing resilient roads that can withstand the effect of climate change, and designing asphalt mixtures that have balanced performance.


Interview conducted by Matt Mann, Research Program Coordinator with Dr. Walaa Mogawer and Ed Naras.



Experiential Education for the Next Generation

In the early 1990s, the Federal Highway Administration (FHWA) established the goals of diversifying its workforce and reaching more underrepresented groups of students. FHWA sought to provide as many as possible with opportunities to expand their STEM (Science, Technology, Engineering, Mathematics) knowledge and to encourage them to pursue transportation studies and careers. The FHWA then created the National Summer Transportation Institute (NSTI), and since the program’s start twenty years ago, thousands of students have participated. NSTI programs are held each summer at various colleges and universities throughout the U.S. They offer high-school and middle-school students the opportunity to learn about different transportation fields, to meet with transportation professionals, and to build STEM skills, including those used in transportation careers. In the summer of 2017, in Massachusetts, the NSTI program was held at the University of Massachusetts-Amherst (UMass-Amherst). Over the past six summers the NSTI program at UMass-Amherst has hosted close to 100 students in total.

A defining feature of the NSTI program is that it is 100% free for all participants, including classroom activities and real time experiences in the field. Some NSTI sites have residential programs and others are commuter-based. In the residential programs, the program pays all room and board costs. Another defining feature of the program is its emphasis on having diverse participants, including economically disadvantaged or at-risk students, and students with disabilities.

For the past two years, the NSTI program at UMass-Amherst served high-school students and included both commuter and residential options. In 2017, the program drew participants from Massachusetts, Connecticut, New York, Illinois, California, Puerto Rico, and an international student from Honduras. Eighteen students participated in 2017, including 12 residential students and 6 commuters. Thirty-nine percent (39%) of this year’s participants were female and half of them (50%) were Hispanic, Asian, African American or multiracial.

The 2017 UMass-Amherst NSTI ran for 3 ½ weeks. The curriculum was wide-ranging and multi-modal, and each week focused on a different mode or aspect of transportation and transportation research. Transportation topics covered in the curriculum included aviation and air traffic control, water transportation, bus transit, rail transit, autonomous vehicles (both on-road and aerial, aka drones), driver training and safety, driving simulation, sustainability, pedestrian and bicycle infrastructure, and transportation financing. Students gained both general knowledge on these topics as well as technical skills. They conducted hands-on transit counts, vehicle speed monitoring, bridge infrastructure reviews, and Unmanned Aerial Vehicle exercises in the field and in classrooms.

2017 UMass-Amherst NSTI, Northampton Amtrak Field Trip with MassDOT Director of Rail, Tim Doherty

They learned about software for bridge design, intersection analysis, and 3D modeling. The students met with academic researchers and transportation professionals in the public and private sector, and had multiple field trips each week. Over the last two years, participants visited the John A. Volpe National Transportation Systems Center in Cambridge, the Springfield and Northampton Amtrak stations, the Massachusetts Bay Transportation Authority’s headquarters in Boston and the field office in Northampton, the Westover Air Force Base, the New England Air Museum, the UMass-Amherst Transit Center, and the UMass-Amherst Police Station. The program also provided higher-education and career support for students, with sessions on resumés, internship opportunities, online career and job sites, and college-test prep. The students were encouraged to give daily feedback on the program and asked to provide an overall evaluation at the end of the NSTI session. Of the 2017 participants, all but one said they would recommend the program to a peer or friend. The feedback received will be used to improve the program in future years.

Other universities that have run NSTIs include the University of Massachusetts-Boston, which had a commuter-program for 10 years, 2005 to 2014, and Vermont Tech, which ran two programs in 2017, one for middle-school students and one for high-school students.

MassDOT Secretary Pollack with 2017 NSTI students, UMass-Amherst NSTI closing ceremony

Written by:  Tracy Zafian, UMTC Research Fellow

Using Advanced Science and Technology to Detect Marijuana Use

Massachusetts is one of twenty-nine U.S. states, plus the District of Columbia, that now legally allow marijuana for recreational or broad medical uses or both (full list of these states available here). The Massachusetts Executive Office of Public Safety and Security (EOPSS) recently launched a public safety campaign, Drive Sober or Get Pulled Over, to warn and inform the public about the impairments that marijuana causes in drivers and the increased driving danger when alcohol and marijuana are combined. Marijuana is proven to impact the brain’s ability to function properly. Marijuana’s primary psychoactive ingredient, tetrahydrocannabinol (THC), has been shown to slow reaction times, impair coordination, and decrease decision-making ability.

One challenge for enforcement regarding marijuana use and driving is that impairment from marijuana is more difficult to measure than impairment from alcohol. There is currently no proven equivalent to an alcohol type breathalyzer test that measures blood alcohol concentration (BAC) levels to assess drunk driving. Unlike alcohol that dissolves in water, THC dissolves in fat. As toxicologist Marilyn Huestis discussed in an NPR story, this means that that the length of time that THC lingers in the body varies more than with alcohol, and is influenced by factors such as amount of body fat, type of cannabis product consumed, and frequency of use. It also means that a person’s blood THC levels may not directly correlate to when they are most impaired.  Some states such as Colorado, Washington, Montana and Pennsylvania, define marijuana impairment using blood THC levels to legally define when someone is too impaired to drive. The state regulations in Ohio and Nevada determine impairment by blood tests and urine tests.

The San Diego Police department, and other enforcement agencies in New York, Arizona, and Nevada, have been screening drivers for THC using a mouth-swabbing testing device (the Dräger DrugTest 5000), which can test for the presence of seven drugs, including marijuana. The marijuana test is for delta-9 THC, the active THC compound which creates the high from marijuana. Unlike other components of THC, delta-9 THC typically only stays in a person’s system for a few hours and not days or weeks.  Stanford University researchers have been developing a saliva-based test for THC using magnetic nanotechnology.  Recently, police departments have been pilot testing a handheld breathalyzer for marijuana detection from Hound Labs. The device measures delta-9 THC levels and is able to detect marijuana from either inhaling or edibles. Cannabis Technologies is also developing a marijuana breathalyzer.  These THC detection methods are often used in conjunction with other field sobriety and impairment testing.

In Massachusetts, Drug Recognition Experts (DREs) are specially trained to detect impairment from drug use.  A full DRE exam takes about an hour and includes physiological measures (blood pressure, pulse, eye exams), and performance measures (balance, coordination). As described in a 2016 Boston.com article Massachusetts and other states are now offering a less intensive training, Advanced Roadside Impaired Driving Enforcement (ARIDE), which is still a step above typical field sobriety training.

In a September 2017 Massachusetts Supreme Court decision, the Court found that police cannot use standard field sobriety tests to determine definitively that a driver is too high to drive. The court determined that the standard sobriety tests were developed to evaluate alcohol intoxication and there is not yet sufficient evidence that they are indicative of marijuana intoxication.  Under the ruling, police officers can still conduct field sobriety tests and testify about their observations regarding a driver’s demeanor and ability to perform physical coordination and mental tasks.

Dr. Michael Millburn, a Psychology professor at UMass Boston, has been developing a smart device app to assess driver impairment called DRUID.  This app has been designed to measure cognitive and behavior impairment from marijuana, alcohol, prescription drugs and other brain-based contributors to impairment, such as fatigue. It contains a series of four different tests for reaction time, errors in decision making, motor tracking, and time estimation and balance. The app then integrates the results of each of the individual tests into an overall impairment score. The tests are completed in 5 minutes total.  The app was developed to help people assess their own impairment, but could also be adapted for police use.  The app is currently being tested at Brown Medical School.  Research shows that some types of marijuana have non-linear patterns of impairment following consumption. Apps such as this could be useful for supporting driver safety and important complements to other tools and tests for measuring THC, alcohol, and other substances that can impair driver performance.

Cambridge police officer Jason Callinan, a drug recognition expert, or DRE, performs the Horizontal Gaze Nystagmus (HGN) on Jeremy Warnick, the department's spokesman, as part of a demonstration. (Jesse Costa/WBUR)
Cambridge police officer, Jason Callinan, a drug recognition expert, or DRE, performs a demo of a field sobriety test.   (Source: Jesse Costa, WBUR)

Written by Tracy Zafian, UMTC Research Fellow

Customizing Your Self-Driving Car

In the future, intelligent transportation systems (ITSs) will involve connected vehicles, including driver-assisted vehicles and self-driving cars, as well as on-board mobile devices, sensors, and the software and algorithms that govern the functioning of these devices and their communications. Despite recent improvements, each year tens of thousands of lives are lost and billions of dollars are wasted because of traffic inefficiencies in the United States alone. Improvements in the transportation systems could have an enormous impact on lowering these statistics.

In this research, we aim to establish a new approach in design of safety systems, which is based on the individualization and customization of these systems to specific drivers and their environments. This means that wireless communication protocols, as well as algorithms that communicate to users, can be designed in an intelligent way in order to take advantage of all the statistical data that is available regarding the driver and his/her environment.

To accomplish this objective, we can use the technology to collect driver performance data and subsequently learn driver characteristics and driving strategies. This information, along with data collected from other vehicles and roadside units, can be used to customize the technology to each driver. With this, it is possible to adapt warnings or automatic control strategies to each driver. Meanwhile, vehicle-to-vehicle (V2V) communication can be dynamically tuned to make efficient use of finite bandwidth and guarantee the transmission of information critical to safety.

In this way, we should consider that there is an uncertainty of the message delivery between two specific vehicles, while other vehicles might also transmit simultaneously. Our research shows that by proper adaptation of wireless communication and warning algorithms, we can potentially reduce accident fatalities by a considerable amount.

To understand the benefit of V2V communication, consider a traffic stream where a chain of vehicles moves with same speed. When the first vehicle in the chain brakes, the driver of the following vehicle applies the brake after her perception reaction time (PRT). If no intervehicle communications are employed, vehicle Vi applies the brake after the sum of PRTs up to the driver i. With the communications, this time will change to the communications delay plus PRTs of the driver i. This is shown in Figure 1.

Figure 1. Communications delay versus sum of PRTs, illustrating the time before a driver in a chain applies the brake

Some drivers may think that some of the received warning messages are not needed, because the drivers are aware of their own response time empirically and they know that they can react to stimuli fast. These warning messages are false alarms for these drivers. These warning messages may frustrate the drivers with an overly high number of false alarms, causing them to ignore warnings or even disable the system. To address this issue, we propose estimating the PRT of drivers and personalizing warning messages based on individual PRTs. Figure 2 shows that at the same accident probability for each driver, the false alarm rate can be reduced by at least 30% by employing the estimated individual distribution instead of the population distribution. Thus, it is of vital importance to minimize false alarms so that the system sends warnings only when they are needed.

Figure 2. False alarm rate versus the probability of accident based on using average response time or individual

Now, we should determine how channel access probabilities of vehicles and vehicular communications can be adapted to drivers’ characteristics. In a network of vehicles, each vehicle transmits with a specific probability in the transmission medium. Large channel access probabilities lead the system to excessive interferences and, consequently, low probability of packets being successfully received (success probability), while very small values reduce the success probabilities since the probability of the favorite transmission is low itself. Therefore, there is an optimal value, given both the physical data obtained by vehicular networks and the communications protocol requirements, which results in lower collision probability of vehicles. We can find the expression of packet success probability in a network of vehicles based on channel access probability of vehicle.

We then use a recursive algorithm to tune the transmission probability of each vehicle based on the individual characteristics of drivers. The PRT of the driver, traffic conditions, and communications delay are three factors that play roles in assigning channel access probabilities to vehicles. In simple terms, we categorize the drivers into safe and unsafe drivers based on perception-reaction time. The unsafe vehicles are the ones whose drivers have long perception-reaction time and low distance to the vehicle in front. In other words, unsafe vehicles have higher collision probability. Then we assign different channel access probabilities to unsafe and safe vehicles respectively.

Figure 3(a) illustrates the collision probabilities when channel access probabilities are assumed to be equal for all vehicles. Figure 3(b) shows the scenario in which different channel access probabilities are assigned to unsafe and safe vehicles. The minimum collision probability in the second scenario improves by 25%.

Figure 3(a). Collision probabilities when channel access probabilities are equal for all vehicles
Figure 3(b). Different channel access probabilities are assigned to unsafe and safe vehicles.

Our simulation results confirm that unsafe vehicles need to inform other vehicles of their perilous situation more frequently than do safer vehicles. In other words, with higher channel access probability for unsafe vehicles, we can achieve lower collision probabilities.

Written by Hossein Pishro-Nik, UMTC Research Affiliate and Associate Professor in the Department of Electrical and Computer Engineering (ECE) at UMass-Amherst. This research was supported by the National Science Foundation under Grant CCF– 0844725 (PI: Hossein Pishro-Nik). It is a joint work with ECE PhD students Mohammad Nekoui, Ali Rakhshan, and Mohammad Kohsravi, and Professor Daiheng Ni from the UMass-Amherst Department of Civil and Environmental Engineering. For more information and access to published papers, please visit http://www.ecs.umass.edu/ece/pishro/publications.html.

Keeping Cyclists Safe! UMTC Research Spotlight on YouTube


Want to learn more about bicycle safety? PhD student Nicholas Fournier of UMass Amherst talks about his two research studies currently being conducted at UMass. Mr. Fournier is studying for a PhD in transportation engineering and an MS in regional planning at the University of Massachusetts, Amherst. View Mr. Fournier discussing his research at this link. One of the highlighted studies used the UMass advanced driving simulator to test how well drivers approaching intersections understand different on-road bicycle infrastructure, such as bike boxes and merged bike lanes, which are designed to reduce left-hook bicyclist-motor vehicle crashes and promote bicyclist safety. In the second study, Mr. Fournier developed a sine-wave model for estimating annual on-road bicycle travel demand in cities where bicycle demand can fluctuate considerably across seasons. The model reduces the number of sample counts needed to develop an estimate for bicycle demand, making it easier for researchers and practitioners in a city to measure bicycle ridership and the overall safety of their road infrastructure for bicyclists.



Safety First! Are You a Distracted Driver or a Distracted Pedestrian?

The annual number of pedestrians hit and killed by vehicles in the United States is now at its highest level in more than 20 years. In March 2017, the Governors Highway Safety Association (GHSA) released a report showing an 11 percent increase rise in the number of pedestrian deaths between 2015 and 2016, and a 25 percent increase in these deaths over the past five years. The report estimates here were almost 6,000 pedestrian fatalities in 2016 and pedestrias now account for 15 percent of all traffic deaths. The rise in pedestrian fatalities from 2015 to 2016 was the highest annual increase in both the total number and percentage growth in the 40 years that these national data have been recorded.

The GHSA figurpedses are calculated based on pedestrian fatalities for January to June 2016 and then extrapolated for the rest of the year. For this six-month period, 2,660 pedestrians died in traffic crashes nationwide. Four states accounted for 43 percent of these fatalities: California (405 pedestrian deaths); Florida (277); Texas (242); and NewYork (137). Massachusetts had 38 pedestrian deaths in this time frame( 1.4 percent of the total).

Source: Seattle Times

The GHSA identified several factors that could be contributing to the rise in pedestrian deaths, including the following.

  • More driving. People are driving more now, with the economy improving and gas prices down from their historic high levels ($4+/gallon) earlier this decade. Federal Highway Administration data released in February 2017 show that in 2016, people in cars, minivans, SUVs, and trucks drove a record 3.22 trillion miles on the nation’s roads and highways. This is an increase of 3 percent over 2015, and the fifth straight year of increased total mileage.
  • Alcohol. According to the GHSA report, 15 percent of pedestrian taffic deaths involve a drunk driver, and 34 percent of the pedestrians killed in traffic accidents themselves have blood alcohol levels above the legal limit of 0.08.
  • Lack of pedestrian visibility. Many of the pedestrian fatalities occurred in conditions where the pedestrians may not be very visible to drivers. The GHSA found that 74 percent of pedestrian deaths occurred at night, and 72 percent of those killed were not at a roadway intersection.
  • In recent years, as cell phones and other portable communication and entertainment devices have become more ubiquitous, there has been an increase in crashes and injuries attributed to distraction. Drive distraction is considered one of the top three causes of traffic fatalities in general—the other top causes are alcohol and vehicle speed—and one of three main causes for pedestrian fatalities. The National Highway Transportation Safety Administration (NHTSA) found that driver distraction contributed to 3,477 traffic crash-related deaths and 391,000 injuries in 2015. As discussed in a recent National Public Radio piece, there are also concerns about the impact of pedestrians’ own distractions on pedestrian safety

A comprehensive research literature review on the impact of electronic device use on pedestrian safety was conducted by Robert Scopatz and Yuying Zhou (2016). The literature review was part of a larger research project examining whether electronic device use by drivers and pedestrians significantly affects pedestrian safety. The literature review included sections on distracted pedestrians, distracted drivers, and pedestrian-driver interactions, and examined real-world studies, simulator studies, and other collected data in these three areas. There have been no studies thus far showing a direct cause-and-effect link between distraction and pedestrian crash risk. Nonetheless, there is clear evidence that distracted drivers face increased crash risks and that distraction impacts how pedestrians walk, react, and behave, including safety-related behaviors

Scopatz and Zhou found only one study (Brumfield and Pulugurtha, 2011) to date that examined pedestrian-vehicle conflicts and the role of distraction due to handheld electronic device use. That study’s researchers observed 325 pedestrian-vehicle interactions at seven midblock crosswalks on a university campus in Charlotte, North Carolina. They found that 29 percent of pedestrians and 18 percent of drivers were noticeably distracted (talking on a cell phone or texting) at the time the pedestrian and vehicle were nearing the crosswalk. Further, the researchers calculated that distracted drivers were more than three times more likely to be involved in a conflict at the midblock crosswalks than distracted pedestrians. Government legislators in Montreal, Quebec, and New Jersey have proposed banning cell phone texting for pedestrians while they are crossing the street. These proposals have not received much support thus far.

Research is needed to dig deeper into the issues around pedestrian fatalities with specific focus on distraction.

Some key questions remain:

  • How distractions (for drivers and pedestrians) exacerbated by hazards that are already present?
  • With the encouragement of Bicycling and Pedestrian activity for healthy communities, how will this impact the grown problem?
  • What type of solutions are States considering for solutions? One recent report published in March of 2017,  Consensus Recommendations for Pedestrian Injury Surveillance aims to offer guidance in tracking, recording and prevention.

By: Tracy Zafian, UMTC Research Fellow with input from Affiliate Researcher, Karin Goins from UMass Medical


Are Pedestrian Fatalities Related to Income and Race?

Pedestrian fatalities in the United States rose by 25 percent over the past 5 years, according to a 2017 report by the Governors Highway Safety Association (GHSA). As pedestrian fatalities have increased, some populations are more at risk than others.

Dangerous by Design 2016, an analysis by Smart Growth America (SGA) of pedestrian fatalities over a 10-year period (2005–2014), looked at data from the 104 largest metro areas in the United States and for each state, by income and by race. This analysis found that the poorer a metro area is, the more likely that pedestrians are to be hit and killed by a motor vehicle. There are a number of contributing factors to this finding. For one, poorer communities and neighborhoods typically have less road infrastructure to support pedestrian safety than more affluent places, including fewer safe, well-maintained sidewalks with adequate night lighting, fewer safe mid-block and intersection crosswalks, and fewer traffic calming measures such as narrow roads and speed humps. Additionally, residents in poorer communities and neighborhoods, especially in urban areas, have lower levels of car ownership and more dependence on walking and transit. This leads them to walk more frequently and makes them more likely to walk to destinations that are not considered pedestrian friendly, such as big shopping centers and along high traffic volume roadways with little pedestrian infrastructure.


Source: Transportation for America.

SGA’s research found connections between pedestrian deaths and median household income and also between pedestrian deaths and race. People of color were overrepresented among pedestrian families in 42 of 49 states and the District of Columbia, and for the United States as a whole. Overall, people of color comprised just over one-third of the U.S. population but almost half of the pedestrian deaths. The greatest proportional risks were for African Americans, with 12 percent of the population and 19 percent of pedestrian deaths, and for Native Americans, with 0.7 percent of the population and close to 3 percent of the deaths. The racial disparities were especially dramatic in some states. In Louisiana, people of color were nine times more likely to be killed than white people, and in Texas, the risk was almost three times as great. In Massachusetts, the risk was only slightly elevated; people of color comprised 22 percent of the state population and 24 percent of the pedestrian fatalities.


Source: Smart Growth America, Dangerous by Design 2016.

As with the income-based findings on pedestrian fatalities, the race-related findings reflect the fact that, as with low-income communities, communities comprising mainly people of color have more residents without car access who walk for transportation and they walk more often and for longer distances. However, SGA found that even after controlling for their residents’ amount of walking, these communities still had higher rates of pedestrian deaths. This suggests that these communities have disproportionately unsafe conditions for pedestrians

To date, only a few experimental studies have been conducted on-road to measure the likelihood of drivers’ responses yielding to pedestrians of different races. The first such study took place at a midblock marked crosswalk in downtown Portland, Oregon, and was conducted by Tara Goddard and Kimberly Barsamian Kahn, both from Portland State University, and Arlie Adkins from the University of Arizona (2016). For this research, individual male pedestrian participants, who were all clearly identifiable as either African American or white, stood at the edge of the crosswalk, looking as though they’d like to cross. The researchers measured the number of cars that passed each pedestrian before a driver stopped at the crosswalk for them, and the amount of time each pedestrian had to wait to cross. Each of the six pedestrian participants—three white and three African American—were of similar build, wore similar clothing, and were instructed to behave similarly. The researchers observed a total of 173 driver-pedestrian interactions. On average, the African American pedestrians waited 32 percent longer and were passed by twice as many cars before crossing, as compared to the white pedestrians.

University of Nevada researcher Courtney Coughenour and colleagues conducted a similar study in Las Vegas. As she described in a discussion earlier this year with National Public Radio correspondent Shankar Vedantam, for their study, the researchers included two different midblock crosswalks, one in a low-income neighborhood and one in a high-income neighborhood, and two female pedestrian participants, one white and one African American. The pedestrians were both of similar build, wore identical outfits, and acted similarly while they waited at the edge of the crosswalk for drivers to stop for them. The midblock crosswalks were on multilane roads. The researchers measured both the number of cars that passed in the nearest lane before stopping for the pedestrian and the number of cars that drove around the pedestrian while they were crossing the street. In total, 124 pedestrian crossings were observed for the two crosswalks. Overall, drivers were less likely to stop for the pedestrians waiting to cross at the high-income crosswalk than the low-income one, regardless of race. At the high-income crosswalk, once the pedestrian was in the roadway, drivers were statistically more likely to pass through the crosswalk and not yield to the African American pedestrian than they were with the white pedestrian. Drivers were also less likely to yield to the African American pedestrian at the high-income crosswalk than at the low-income crosswalk. One contributing factor to these results could be that the high-income crosswalk was on a street with more travel lanes and a higher posted speed limit, 45 mph, than the street with the low-income crosswalk, 35 mph.

In both crosswalk-pedestrian race studies, no information was collected on any of the drivers, such as their race, income, or how they made their decision on whether or not to stop for pedestrians at the crosswalks. Nonetheless, it appears that some drivers could have some race or class-related conscious or unconscious biases in this regard. Of most concern from a safety perspective is drivers’ failure to yield to African American pedestrians already crossing the street in the high-income neighborhood in the Las Vegas study. The failure of drivers to yield at multilane midblock crosswalks is a known cause of many pedestrian fatalities and injuries, and the results here suggest driver biases could put some pedestrians more at risk than others.


Written By: Tracy Zafian, UMTC Research Fellow

Don’t Get Derailed: The MBTA Is Still a Safe Transit System; Investment in Infrastructure Is Needed to Keep It That Way

The Green Line had six trolley derailments in 2016, according to the recently updated National Transit Database, and as described in a recent Boston Globe article. Combined with two subway maintenance vehicle derailments, this positioned the MBTA as the transit agency with the most derailments last year in the United States.

So what is behind this data? Why should we look closer?


In 2015, the National Transit Database derailment figures began including derailments of vehicles not intended for passengers, including maintenance vehicles. This increased the MTBA’s reported annual derailments slightly. It is also worth noting that these published figures do not include derailments for commuter rail systems, as those incidences are instead reported to the Federal Railroad Administration.

The MBTA is this country’s fifth-largest mass transit system, based on daily ridership, and has the busiest light rail system (Green Line and Ashmont-Mattapan high-speed line). Derailments are less common for parts of the MBTA system beyond the Green Line. In 2016, the MBTA had its first derailments on the Orange and Red lines since 2001; both derailments involved vehicles that are not for passengers.

Sensationalizing this data only serves to create poor public opinion, and the MBTA leadership feels confident the MBTA system, including the Green Line, is safe. In 2016, none of the derailments resulted from a collision, and no passengers or employees were injured in a derailment. The number of annual derailments for the MBTA is down significantly (over 75%) from a high of 29 derailments in 2007, and the MBTA is committed to reducing derailment on the Green Line further through improved maintenance and monitoring. Even when no one is hurt, derailments impact service delivery and can shut down lines or stations for hours.  They can also undermine riders’ support of and trust in the MBTA.

There are, however, other challenges to the MBTA system, including its age and need for additional funding, as well as for maintenance. The Green Line is the oldest subway line in the United States, with tunnel sections dating back to 1897, and it is one of the oldest light rail systems above ground as well. Other systems topping the 2016 list of derailments include New Orleans and the San Francisco Municipal Railway, which are also historic systems. This is another reminder of the importance of funding investments in maintaining and rebuilding aging infrastructure. The challenge isn’t limited to the MBTA. The U.S. DOT estimates a nearly $90 billion backlog in transit infrastructure maintenance, just to preserve existing systems. In 2015, the MBTA’s maintenance backlog was over $7 billion, and it would need to spend about $765 million annually to eliminate the maintenance backlog over 25 years.

Although rapid transit remains a safe way to travel compared to travel by car, recent crashes on commuter railroads in other parts of the country are drawing attention to the limitations of existing infrastructure. Investments are necessary to ensure safe, reliable, and efficient mobility for the economic competitiveness and vitality of cities like Boston for decades to come.

By: Tracy Zafian, UMTC Research Fellow, and Eric Gonzales, UMTC Research Affiliate


YouTube Research Spotlight: Research to Improve At-Grade Rail Crossing Safety

The UMTC Research Section Launches a Research Spotlight YouTube Channel. We are showcasing research currently being conducted on “At-Grade Rail Crossing Safety” by Radhameris Gomez.  Ms. Gomez is a PhD candidate in the UMass Transportation Engineering Program at the University of Massachusetts, Amherst. View the overview video (3 minutes) or the extended video (10 minutes) to find out how she became interested in studying transportation engineering.

TrailCrashes at roadway-railroad intersections happen far too often. Federal Railroad Administration data show that 2,025 such crashes occurred in the United States in 2016, resulting in 265 fatalities and 798 injuries. There have been a number of roadway-rail intersection crashes recently. For example, in Florida, an Amtrak train collision with a car left one person dead; in Arkansas, one person was killed and another injured when their car crossed into a train’s path; and in North Carolina, a train crashed into a car that stopped on the railroad tracks when the safety arms came down, and the car driver was killed. Earlier in March, a freight train collided with a charter bus in Mississippi that had become stuck on a rail crossing with low clearance on the crest of a slope. Four people were killed and others injured; it was the 161st crash since 1976 at that crossing. After a March snowstorm, a local DPW worker in Longmeadow, Massachusetts, died when his snowplow backed onto railroad tracks when a train was coming. At that intersection, there are no gate arms or traffic signals to help warn drivers when a train would be coming; there had been five other crashes and four other deaths at that location since the 1970s.

Previous studies have examined primary contributing factors for grade-crossing train-car crashes and how these crashes can be prevented. Jeff Caird and colleagues at the University of Calgary analyzed over 300 grade-crossing crashes in Canada (2002). They estimated that adding flashing lights to a rail crossing without them has the potential to reduce crashes by over 60 percent, as compared to crossbucks alone. Michael Lenné and colleagues at Monash University in Australia conducted a driving simulator study (2010) on driving behavior at three different types of at-grade rail crossings: stop-controlled, with flashing lights, and with a traffic signal. The researchers found that participants slowed their vehicles the most when approaching rail crossings with flashing lights.

By: Tracy Zafian, UMTC Research Fellow


Decriminalization of Marijuana and Potential Impact on CMV Drivers

Captain Darrin Grondel is the Director of the Washington Traffic Safety Commission and a Captain with the Washington State Patrol. At the 2016 Commercial Vehicle Safety Research Summit, Captain Grondel discussed drugged driving and its impact on traffic safety. The following are some highlights of Captain Grondel’s presentation.


As marijuana becomes legal for recreational use across the country, transportation safety stakeholders grapple with the realities and challenges inherent in the new legislation. Currently, the possession and use laws in the U.S. are described as a patchwork, as their look and structure remain very different, depending on the state.

What’s more, the strength of marijuana has changed dramatically over the last several decades. While most governmental studies involving marijuana involve THC levels of 3-6%, the substances now showing up in a variety of forms (oils, edibles, vaping) have THC levels closer to 30-40%.  While many issues around legalization of marijuana remain unclear, what we do know is that incidences of drugged driving are going up, and must be mitigated.

The overarching issue around legalization of marijuana remains the existing knowledge gap around the effects of cannabis (and other drugs) on driving. One reason for this gap is a complete lack of data around drugged driving; including crash and inspection data, and information about the types of drugs being used, and in which combinations.

Another major issue is public indifference. Drivers tend to see drunk driving as clearly dangerous and socially unacceptable, but don’t feel strongly one way or the other about drugged driving. Many people don’t know the level at which drugs impair them, and haven’t been educated about the dangers of driving while taking something as benign-seeming as cough medicine. The Pacific Institute for Research and Evaluation conducted the PIRE Roadside Survey in 2014 and 2015, where they surveyed 926 drivers in 5 counties. Of drivers who said they’d used marijuana within two hours of driving, 67% said that it made no difference in their driving. Knowing what we do about the effects of THC on the brain, it seems unlikely that drivers would be unaffected.

What remains clear is that drugged driving is much more complicated than drunk driving, and that these types of crashes are on an upward trend. Less clear, are the details around how drivers are affected, how long those effects last and how police will know a drugged driver when they see one.

Summary by: Kathryn Slater, UMTC Research