Gregory M. Fitch

Toward Developing an Approach for Alerting Drivers to the Direction of a Crash Threat

Objective: This study explored the potential for auditory and haptic spatial cuing approaches to alert drivers to the direction of a crash threat. Background: For an automobile equipped with multiple crash avoidance systems, effective cuing of the crash threat direction may help the driver avoid the crash. Because the driver may not be looking in the direction of a visual crash alert, nonvisual crash alerts were explored as an additional means of directing attention to a potential crash situation. Methods: In this in-traffic study, 32 drivers were asked to verbally report alert direction in the absence of any crash threats. Driver localization accuracy and response time were examined as a function of eight alert locations surrounding the vehicle and four directional alert approaches (auditory, haptic, haptic and auditory, and haptic and nondirectional auditory). The auditory directional alert approach used four speakers and broadband alert sounds, and the haptic directional alert approach used vibrations generated at various locations on the bottom of the drivers seat. Results: Overall, relative to the auditory alert approach, the three approaches that included the haptic seat alert component reduced correct localization response times by 257 ms and increased percentage correct localization from 32% to 84%. Conclusion: These results suggest that seat vibration alerts are a promising candidate for alerting drivers to the direction of a crash threat. Application: These findings should facilitate developing a multimodality integrated crash alert approach for vehicles equipped with multiple crash avoidance systems.

Active Text Drawing Styles for Outdoor Augmented Reality: A User-Based Study and Design Implications

A challenge in presenting augmenting information in outdoor augmented reality (AR) settings lies in the broad range of uncontrollable environmental conditions that may be present, specifically large-scale fluctuations in natural lighting and wide variations in likely backgrounds or objects in the scene. In this paper, we present a active AR testbed that samples the users field of view, and collects outdoor illuminance values at the participants position. The main contribution presented herein is a user-based study (conducted using the testbed) that examined the effects on user performance of four outdoor background textures, four text colors, three text drawing styles, and two text drawing style algorithms for a text identification task using an optical, see-through AR system. We report significant effects for all these variables, and discuss design guidelines and ideas for future work

The Risk of a Safety-Critical Event Associated With Mobile Device Use in Specific Driving Contexts

Objective: We explored drivers’ mobile device use and its associated risk of a safety-critical event (SCE) in specific driving contexts. Our premise was that the SCE risk associated with mobile device use increases when the driving task becomes demanding. Methods: Data from naturalistic driving studies involving commercial motor vehicle drivers and light vehicle drivers were partitioned into subsets representative of specific driving contexts. The subsets were generated using data set attributes that included level of service and relation to junction. These attributes were selected based on exogenous factors known to alter driving task demands. The subsets were analyzed using a case-cohort approach, which was selected to complement previous investigations of mobile device SCE risk using naturalistic driving data. Results: Both commercial motor vehicle and light vehicle drivers varied as to how much they conversed on a mobile device but did not vary their engagement in visual–manual subtasks. Furthermore, commercial motor vehicle drivers conversed less frequently as the driving task demands increased, whereas light vehicle drivers did not. The risk of an SCE associated with mobile device use was dependent on the subtask performed and the driving context. Only visual–manual subtasks were associated with an increased SCE risk, whereas conversing was associated with a decreased risk in some driving contexts. Conclusion: Drivers’ engagement in mobile device subtasks varies by driving context. The SCE risk associated with mobile device use is dependent on the types of subtasks performed and the driving context. The findings of this exploratory study can be applied to the design of driver–vehicle interfaces that mitigate distraction by preventing visual–manual subtasks while driving.

Compensatory behavior of drivers when conversing on a cell phone

Experimental studies have found that driving degrades when the driver is conversing on a cell phone. Naturalistic driving studies (NDSs), however, have not found conversing on a cell phone to be associated with increased risk of a safety-critical event (SCE). NDSs have found commercial motor vehicle (CMV) drivers to be at decreased SCE risk when conversing on a hands-free cell phone. This study used naturalistic driving data sets to investigate whether driver adaptation took place when drivers of light vehicles and CMVs were conversing on a cell phone. Baseline epochs 30 s prior to cell phone calls were sampled. Drivers’ travel speeds, headways, inclinations to travel in the slowest lane, inclinations to change lanes, and lane-keeping performances were compared. There was no indication that drivers increased their longitudinal safety margins when conversing on a cell phone. Their headways to a lead vehicle did not differ despite CMV drivers significantly increasing their speeds by 4 km/h (2.5 mph) when conversing on a cell phone. However, CMV drivers changed lanes significantly less and light-vehicle drivers unintentionally departed their lanes significantly less when conversing on a handheld cell phone. Overall, the observed performance changes were not substantial. Given that drivers look forward more often when conversing on a cell phone, it is likely that the increased visual attention to the forward roadway may ultimately be why conversing on a cell phone has not been found to increase SCE risk.

Distracted driver performance to multiple alerts in a multiple-conflict scenario

Objective: We investigated whether collision avoidance systems (CASs) should present individual crash alerts in a multiple-conflict scenario or present only one alert in response to the first conflict. Background: Secondary alerts may startle, confuse, or interfere with drivers’ execution of an emergency maneuver. Method: Fifty-one participants followed a pickup truck around a test track. Once the participant was visually distracted, a trailing sedan repositioned itself into the participant’s blind spot while a box was dropped from the truck. Participants received a forward collision warning (FCW) alert as the box landed. Twenty-six drivers swerved left in response to the box, encountering a lateral conflict with the adjacent sedan. Half of these 26 drivers received a lane-change merge (LCM) alert. Results: Drivers who received both the FCW and LCM alerts were significantly faster at steering away from the lateral crash threat than the drivers who received only the FCW alert (1.70 s vs. 2.76 s, respectively). Drivers liked receiving the LCM alert, rated it to be useful, found it easy to understand (despite being presented after the FCW alert), and did not find it to be startling. Conclusion: Drivers who are familiar with CASs benefit from, and feel it is appropriate to generate, multiple alerts in a multiple-conflict scenario. Application: The results may inform the design of CASs for connected and automated vehicles.

Investigating Improper Lane Changes: Driver Performance Contributing to Lane Change Near-Crashes

We investigated the contributing factors that led to the lane change near-crashes recorded in the 100-Car Naturalistic Driving Study using a case-crossover experimental design. Drivers’ visual behavior and vehicle control were compared across a sample of lane change near-crashes and matched baselines. Baseline lane changes were sampled if they occurred prior to the near-crash, had a similar maneuver as the near-crash (including direction and speed), occurred within ± 2 hours from the time of day, occurred in similar light conditions, occurred on a similar day of the week (weekday vs. weekend), occurred on a road that had a similar number of lanes, had a similar placement of surrounding vehicles, and were made by the same driver. A total of 18 lane change near-crashes and 33 baseline lane changes were identified. Left lane change near-crashes appear to have resulted in part because drivers tended to slow down at the start of the maneuver and were less likely to use their rearview mirror. Right lane change near-crashes appeared to have occurred because of more aggressive maneuvering, infrequent turn signal use, and because drivers were less likely to look over their shoulder. Deficiencies in judging the distance and approach rate to adjacent vehicles, as well as circumstances in the environment, may also have played a contributing role.

Field Demonstration of Heavy Vehicle Camera/Video Imaging Systems

To help drivers monitor the road and to reduce blind spots, Camera/Video Imaging Systems (C/VISs) display video from cameras mounted on the truck’s exterior to drivers using displays inside the truck cabin. This report investigated drivers’ performance with C/VISs in a real-world trucking operation. Twelve commercial drivers’ performance with and without a C/VIS was continuously recorded while they each drove for four months. Half of the drivers used a commercially available C/VIS that had a side-view camera on each fender. The other drivers used an advanced C/VIS (A-C/VIS) that had side-view cameras, a rear-view camera, and night-vision capabilities. The results show that when a C/VIS was provided: 1) drivers’ involvement in safety-critical events (SCEs) did not change, 2) the probability that drivers looked forward did not change, 3) drivers were more likely to use the C/VIS at night and when making right lane changes, and 4) drivers indicated that the C/VISs helped them become aware of surrounding objects and merge into traffic. In terms of disbenefits, some drivers indicated that glare from the commercially available C/VIS monitors, as positioned to specifications, could be uncomfortable at night. The A-C/VIS’s advanced features were highly rated by drivers. The rear-view camera was also used more than the left or right fender cameras.

Evaluation of Safety Benefits from a Heavy-Vehicle Forward Collision Warning System

Forward collision warning (FCW) systems are designed to alert drivers to an impending rear-end (RE) crash, to allow drivers to respond to a crash threat sooner, and thus to reduce their impact speed or allow them to avoid a crash altogether. This study estimates the safety benefits that may be attained by deploying an FCW system across the national fleet of heavy vehicles. The approach involved identifying RE conflicts within a heavy-vehicle naturalistic driving data set with the use of algorithms that identified potential RE events and removed nonthreatening events. Since the heavy vehicles in this data set were not equipped with FCW systems, the FCW auditory alarm severity and timing were introduced into the data with existing FCW system algorithms. Driver perception–response times and braking levels to the computed FCW alarms were modeled with actual driver alarm response behavior recorded in a previous heavy-vehicle FCW field operational test. Driver RE collision avoidance behavior, both with and without FCW alarm feedback, was then simulated with a Monte Carlo simulation approach. The simulation assumed that drivers selected the optimal braking response in the event that multiple FCW alarms were triggered. The number of conflicts avoided and the additional response time available before a crash were then used to assess the safety benefits. This study estimated that FCW systems may afford a 21% reduction in heavy-vehicle RE crashes, which translates to 4,800 crashes per year on U.S. highways.

Identifying the Pattern of Localization Responses with a Haptic Seat Intended to Alert Drivers to the Direction of a Crash Threat

The potential safety benefits afforded by emerging automotive crash avoidance systems may be enhanced by implementing a driver vehicle interface (DVI) that effectively communicates the direction of a potential crash threat in a timely, effective, and integrated manner. An in-traffic study by the authors provided evidence that drivers could spatially map eight haptic seat vibration areas to the corresponding directions surrounding the vehicle with 86% localization accuracy (Fitch, Kiefer, Hankey, & Kleiner, 2007). This paper re-analyzed the data from this study to explore the extent to which there were any notable patterns in the observed localization errors. Results indicate there was some tendency for subjects to perceive side (i.e., left or right) seat pan vibration locations as originating somewhat further back than they actually occurred. Furthermore, the pattern of these errors suggest that a haptic seat communicating four directions of crash threat (e.g., front, right, back, and left) may further reduce the low level of localization errors observed with an eight direction haptic seat design.

Comparing Handheld and Hands-free Cell Phone Usage Behaviors While Driving

Objective: The goal of this study was to compare cell phone usage behaviors while driving across 3 types of cell phones: handheld (HH) cell phones, portable hands-free (PHF) cell phones, and integrated hands-free (IHF) cell phones. Naturalistic driving data were used to observe HH, PHF, and IHF usage behaviors in participants’ own vehicles without any instructions or manipulations by researchers. Methods: In addition to naturalistic driving data, drivers provided their personal cell phone call records. Calls during driving were sampled and observed in naturalistically collected video. Calls were reviewed to identify cell phone type used for, and duration of, cell phone subtasks, non–cell phone secondary tasks, and other use behaviors. Drivers in the study self-identified as HH, PHF, or IHF users if they reported using that cell phone type at least 50% of the time. However, each sampled call was classified as HH, PHF, or IHF if the talking/listening subtask was conducted using that cell phone type, without considering the drivers self-reported group. Results: Drivers with PHF or IHF systems also used HH cell phones (IHF group used HH cell phone in 53.2% of the interactions, PHF group used HH cell phone for 55.5% of interactions). Talking/listening on a PHF phone or an IHF phone was significantly longer than talking/listening on an HH phone (P <.05). HH dialing was significantly longer in duration than PHF or IHF begin/answer tasks. End phone call task for HH phones was significantly longer in duration than the end phone call task for PHF and IHF phones. Of all the non–cell phone–related secondary tasks, eating or drinking was found to occur significantly more often during IHF subtasks (0.58%) than in HH subtasks (0.15%). Drivers observed to reach for their cell phone mostly kept their cell phone in the cup holder (36.3%) or in their seat or lap (29.0% of interactions); however, some observed locations may have required drivers to move out of position. Conclusions: Hands-free cell phone technologies reduce the duration of cell phone visual–manual tasks compared to handheld cell phones. However, drivers with hands-free cell phone technologies available to them still choose to use handheld cell phones to converse or complete cell phone visual–manual tasks for a noteworthy portion of interactions.