Craig Shankwitz

Effects of alcohol impairment on motorcycle riding skills

Alcohol intoxication is a significant risk factor for fatal traffic crashes; however, there is sparse research on the impairing effects of alcohol on skills involved in motorcycle control. Twenty-four male motorcycle riders between the ages of 21 and 50 were assessed on a test track with task scenarios based on the Motorcycle Safety Foundations (MSF) training program. A balanced incomplete block design was used to remove confounding artifacts (learning effects) by randomizing four BAC levels across three test days. In general, intoxicated riders demonstrated longer response times and adopted larger tolerances leading to more task performance errors. Most of the alcohol effects were evident at the per se 0.08% alcohol level, but some of the effects were observed at the lower 0.05% alcohol level. The effects of alcohol on motorcycle control and rider behavior were modest and occurred when task demand was high (offset weave), time pressure was high (hazard avoidance for near obstacles), and tolerances were constrained (circuit track). The modest effects may be due to the study design, in which experienced riders performed highly practiced, low-speed tasks; alcohol at these levels may produce larger effects with less experienced riders in more challenging situations.

The Minnesota Mobile Intersection Surveillance System

Detailed crash analyses indicate that poor gap selection, rather than stop sign violation, is the primary causal factor in crashes at rural, unsignalized intersections. To determine under what conditions the gap selection process fails, a transportable rural intersection surveillance system has been designed and implemented. The system can be installed at any rural intersection, and can be used to collect data regarding the gap acceptance behavior of drivers at the rural intersection. Described herein is the design and performance of the transportable rural intersection surveillance system. This system will be deployed at eight rural intersections in eight US states, from April 2006 through December 2008. Data collected by the system will be used to determine whether regional differences in gap acceptance behavior exist. If differences exist, they will be quantified and used in the design of an intersection decision support system, a device under development designed to assist a driver at a rural intersection with the gap selection process

DGPS-based lane assist system for transit buses

Metro transit and the Minnesota DOT cooperatively operate a BRT-like system throughout the Twin Cities, Minnesota, metropolitan area. During peak congestion periods, buses operate on specially designated road shoulders (albeit at speeds significantly lower than limits posted for the adjacent highway). This allows buses to bypass congested roadways, enabling the bus to maintain its schedule regardless of traffic conditions. One of the problems faced by drivers using the shoulders is that the shoulders are typically no more than 3.1 m wide; a 12 m long transit bus measures 2.9 m across the rear view mirrors, and 2.6 m across the rear dual wheels. These narrow lanes require that a driver maintain a lateral error of less than 0.15 m to avoid collisions. This is a difficult task under the best conditions, and degrades to nearly impossible during conditions of bad weather, low visibility, high traffic congestion, etc. Metro transit drivers are not required to use the shoulders; shoulder use is left to their discretion. When poor conditions are encountered, many drivers choose not to use the shoulder. However, these poor conditions offer the greatest benefit of the bus-only shoulder use, creating an operational paradox. To minimize the effect of poor conditions on the use of bus-only shoulders, a lane assist system has been developed by the Intelligent Vehicles Lab at the University of Minnesota to help bus drivers under these difficult conditions. The system uses carrier phase, dual frequency differential GPS, a lane-level, high density, high accuracy geospatial database, and a lateral control algorithm for lateral assistance, radar for obstacle detection (critical in low visibility), and graphical, haptic, and tactile driver interfaces to provide guidance information to a driver. In addition to the system description, performance of the system on a operational bus-only shoulder is provided.

An evaluation of a lane support system for bus rapid transit on narrow shoulders and the relation to bus driver mental workload.

The use of dedicated bus shoulders is a key method for implementing bus rapid transit (BRT) in areas that do not have the space for additional infrastructure. However, the narrow width of the bus shoulder and the need to anticipate traffic hazards in the adjacent lane can both be significant stressors for bus drivers. Bus driver mental workload and stress in response to these conditions should be a significant concern both for operational safety and driver health. This pilot study evaluated the potential stressors of traffic density and shoulder width in the context of an express BRT service in a large US metropolitan area. In addition, the study considered the potential role of a prototype lane support system (LSS) to support vehicle control within the narrow shoulder boundaries. Ten experienced bus drivers drove an actual route with an instrumented bus equipped with and without LSS. Self-reported effort was recorded along with performance measures of speed and position control relevant to mobility and safety objectives. Bus drivers did note stressors in the BRT environment and the prototype LSS. However, the use of the shoulder during high-density traffic conditions did improve mobility. Moreover, the LSS did enhance safety on the shoulder when there was high-density traffic in the adjacent lane. However, there was no evidence that the LSS reduced bus driver workload while operating in the narrow shoulder. Future research should consider the impact of BRT operations and support systems on bus driver mental workload and stress, and support the deployment of such devices for bus operations on shoulders during high traffic volumes.

Rural Expressway Intersection Surveillance for Intersection Decision Support System

More than 30% of all vehicle crashes in the United States occur at intersections; these crashes result in nearly 9,000 annual fatalities, or approximately 25% of all traffic fatalities. Moreover, these crashes lead to approximately 1.5 million injuries per year, accounting for approximately 50% of all traffic injuries. In rural Minnesota, approximately one-third of all crashes occur at intersections. AASHTO recognized the significance of rural intersection crashes in its 1998 Strategic Highway Safety Plan and identified the development and use of new technologies as a key initiative to address the problem of intersection crashes. A study of 3,700 rural Minnesota intersections showed that right-angle crashes account for 36% of all rural intersection crashes. Approximately 50% of crashes at intersections that have higher than expected crash rates are right-angle crashes. Further investigation also found that poor gap selection is the predominant causal factor in these crashes. To address the problem of poor...

Range sensor evaluation for use in Cooperative Intersection Collision Avoidance Systems

The Intelligent Transportation Institute at the University of Minnesota is developing a Cooperative Intersection Collision Avoidance System - Stop Sign Assist (CICAS-SSA) for rural intersections as an alternative to signalized intersections. When deployed, the system will provide a driver stopped at a thru-stop intersection information about the available gaps in the mainline road traffic stream. The system uses surveillance sensors alongside the major road to determine the state1 of the intersection; this state information is used to determine whether the gaps that exist are unsafe, thereby triggering a warning to a driver not to initiate the desired maneuver. The system is capable of sending intersection state information to the vehicle (I2V) so that gap information can be displayed in the vehicle. Low cost automotive radar/laser sensors form the basis of the surveillance system. Described herein is a performance evaluation of a Delphi ESR radar sensor (ESR), an Ibeo Lux laser sensor (LUX), and a Smartmicro Umrr9 radar sensor (UMRR9). Each sensor was mounted adjacent to the shoulder on US 52 while a probe vehicle equipped with dual frequency, carrier phase DGPS was driven past. The accuracy of the position and speed measurements for each sensor were determined by comparison with the DGPS position and speed measured at the probe vehicle. An analysis was conducted to determine which sensor provided the best performance:cost ratio when used as a CICAS-SSA mainline sensor.

LIDAR-based vehicle tracking for a virtual mirror

Low visibility conditions and blind zones induce hazards to driving and have been shown to be a cause of many automobile crashes every year. In order to reduce these effects, the virtual mirror, a computer-generated display that uses a high-accuracy DGPS system coupled with an onboard geo-spatial database, was used to render the view that the driver would see in a mirror-like display. In order to correctly display and integrate the information (lane boundaries, etc.) from the database with the sensed objects, a real-time method of locating and tracking nearby vehicles was developed. This paper outlines the algorithms and equipment used to achieve real-time vehicle tracking based on a scanning laser range sensor, and the experiments performed to determine the accuracy of the virtual mirrors ability to correctly display moving vehicles in the sensors field of view.

Advanced range sensor processing using DGPS and a geospatial database

Manufacturers of automotive radar typically use narrow beam angles to minimize the number of detected objects (traffic signs, guard rails, etc.) which ought not to pose a threat to the host vehicle. Although narrow beam angles are sufficient for some applications, namely automatic cruise control (ACC), wider fields of view are necessary for driver assistive systems. In order to make wide field of view range sensors perform well for driver assistive systems, a novel radar processing technique has been developed which integrates vehicle location provided by a high accuracy Differential Global Positioning System receiver and a highly detailed Geospatial Database map into the radar processing algorithm. Road objects such as road shoulders and road islands are used to delineate the driveable road surface. Objects detected by the range sensor which are located off of the driveable road surface are identified as such. Relevant vehicle systems (i.e., Heads Up Display or Collision Avoidance) can use this information to minimize false positives. This radar processor was implemented on an International snowplow and results from a series of experiments using this vehicle on Minnesota Trunk Highway 101 between Rogers and Elk River are presented. The system proved very effective at minimizing radar false positives.

The envelope of spectral power for stochastic processes

Given a partial covariance sequence of a real stationary zero-mean stochastic process, one method of estimating the power spectrum is that of Maximum Likelihood. The Maximum Likelihood estimate represents an envelope of maximum spectral content corresponding to stochastic processes which may be complex. We determine the envelope of spectral content which is consistent with the assumption that the underlying stochastic process is real.

ALX: autonomous vehicle guidance for roadway following and obstacle avoidance

This paper presents results of research done on an Autonomous Land Experimental Vehicle (ALX). ALX is able to autonomously follow roadways through the use of a vision system and to execute obstacle detection and collision avoidance using a suite of range sensors. This paper describes the embedded real-time control system for ALX based on a multiprocessor, multitasking architecture and presents the algorithms that were used for visual perception, path tracking, obstacle detection and collision avoidance. Experimental results are also presented.