Intelligent transportation systems (ITS)

This project evaluated how driver interaction with an in-vehicle navigation system (IVNS) affects driving performance and safety. Researchers collected measures of simulated driving performance during interaction by 13 different subjects with an IVNS digital map display, using a Honda Acura placed within a fixed-base wrap-around driving simulator. Subjects (Ss) navigated along a maze-like route laid out within a simulated road grid. Dummy Global Positioning System (GPS) coordinates, corresponding to the position of the vehicle in the grid, were transmitted to the IVNS and updated continuously as vehicle position in the simulation environment changed. A digital map of the grid, with an icon representing vehicle representing vehicle position superimposed, was displayed on a laptop computer placed in the Acura. Under the control condition, Ss were not given turn instructions. Results indicate that for the test relative to the control condition: * Visual interaction with the IVNS display was greater and task completion times longer. * More variability in vehicle control was observed for measures of average vehicle speed, peak speed, percent braking time, peak braking pressure, and vehicle heading. Subjective responses from simulated driving and a separate group of on-road Ss identify both navigation benefits and possible safety problems with the system. It is a reasonable assumption that increased variability in driving performance elevates driving accident risk. Both the simulated driving and subjective response results, therefore, point to possible safety implications in IVNS use for the driving public. The findings suggest that as IVNS use becomes more widespread, both navigation benefits and possible adverse driving safety effects of such systems need to be considered.

This report examines the use of the Connectivity-Clustered Access Method (CCAM) to improve network operations. The expected I/O cost for many network operations can be reduced by maximizing the Weighted Connectivity Residue Ratio (WCRR), i.e., the chance that a pair of connected nodes that are more likely to be accessed together are allocated to a common page of the file. An access method for general networks that uses connectivity clustering, CCAM supports the operations of insert, delete, create, and find, as well as the new operations, get-A-successor and get-successors, which retrieve one or all successors of a node to facilitate aggregate computations on networks. The nodes of the network are assigned to disk pages via a graph partitioning approach to maximize the WCRR. CCAM includes methods for static clustering, as well as dynamic incremental reclustering, to maintain high WCRR in the face of updates, without incurring high overheads. The report also describes possible modifications to improve the WCRR that can be achieved by existing spatial access methods. Experiments with network computations on the Minneapolis road map show that CCAM outperforms existing access methods, even though the proposed modifications also substantially improve the performance of existing spatial access methods.

This research established a concise set of human factors guidelines for evaluating devices and also assessed the Genesis project's message format suitability. It provides a literature review and synthesis of human factors relating to the use of devices, such as cellular phones, pagers, and car radios, and to other tasks that drivers may undertake while driving. The work revealed that the use of information-providing devices such as pagers or PDAs will increase information processing workload; that the findings from the use of a particular device under particular conditions cannot be generalized to other devices or conditions; and that only empirical findings will show whether and under what conditions reading traffic information displayed on pagers or PDAs will seriously degrade driving performance. Work on message format evaluation showed that message formats could be improved and that improvement would result in better legibility and comprehension and decrease the time a driver would attend to the display.

An essential component of Advanced Traveler Information Systems, in-vehicle route displays give drivers route options, alert them to incidents, and show their present location. In this report, researchers explore multimedia interfaces to present route information to travelers using map, text, and auditory-based representations, focusing on developing portable multimedia interfaces. The report concludes that the graphical user interface (GUI) for display of route information is satisfactory for small road maps. The GUI also proved useful for visually checking map quality. The Tcl/Tk toolkit, in which the GUI was developed, is a reasonable tool to design an interface because it is portable to many platforms. Speech generation tools are not yet robust enough for use with large maps. Future work could include extending the GUI to provide a hierarchical display for large roadmaps, extending the amount of information conveyed to the user, and improving speech generation techniques.

Advanced Traveler Information Systems (ATIS) offer the potential to help a driver find the quickest and safest route to a destination. An effective navigation system requires effective route planning services, which need to provide three facilities: route computation, route evaluation, and route display. This project focuses on route planning algorithms for ATIS. The cost models and performance studies in this report show that single-pair algorithms can outperform traditional algorithms in many situations.

Drivers often perform tasks alone or in combination that don't relate to control of their vehicle. This experiment evaluates the impact on simulated driving of performing non-driving tasks. The results showed that some of these tasks significantly degraded driving performance. The task that required drivers to use the map device caused the greatest problem. In addition, older drivers performed less well than younger drivers. The study shows objective reasons for evaluating the trade-offs between maximizing traffic safety and providing drivers with information that requires a high degree of visual attention. In the experiment, drivers performed the following secondary tasks alone, as pairs, or all three simultaneously: talking on a simulated cellular telephone, finding an object in an enclosed container, and using a special radio with head-up map and text displays. The experiment required drivers to maintain speeds of 25 to 30 miles per hour, keep the car centered in their traffic lane, and respond quickly to the appearance of simulated brake lights. Researchers divided subjects into four groups of 10 members each: young females and males with an average age of 31 and older females and males with an average age of 70.

This report summarizes human factors research for IVHS/ITS projects and focuses on the following five tasks: The comparative evaluation of ITS in-vehicle information prototypes. This experiment compares drivers' reaction to the use of three forms of in-vehicle information systems in driving simulation: the Delco prototype, the Volvo Dynaguide prototype, and a procedure that presented a voice generation information system. It includes recommendations for in-vehicle device designs. The evaluation of driver response to an in-vehicle ITS technology. This experiment evaluated drivers' responses to information presented on an in-vehicle ITS. Geographic databases for IVHS management. This work extends the concept of relational databases to model traffic information in an approach that uses abstract data types and triggers. The improvement of simulation facilities. This task describes the acquisition and installation of equipment and software to improve simulation capabilities at the Human Factors Research Laboratory and its impact on research efforts. In-vehicle collision avoidance warning systems for IVHS. This experiment examined the effects of presenting warnings of vehicle proximity on turn decisions.

The success of in-car devices that aid drivers depends in part on driver reaction and acceptance. This project looks at the human factors considerations for the GENESIS Program, which studies the use of personal communication devices to deliver real-time traffic and transit information services. Researchers used vehicle simulation to learn more about the impact of the use of GENESIS devices. The report includes a discussion of human factors issues for consideration during the operational test evaluation phase and recommends suggestions to improve in-car computer screens and for future simulation studies.

The purpose of the MINDER program is to create the common simulation resource for human factors and safety researchers in respect to Minnesota Department of Transportation (Mn/DOT) programs. To accomplish this, we have created a simulation capability to re-create part of the I-35W Metropolitan area corridor from the Cross-town commons to just south of downtown Minneapolis. Our purpose in creating this was to allow researchers on different programs to use a common simulation environment. This was the first element of MINDER which was proposed as a larger program to include other segments of the freeway systems of the Twin City Metropolitan region. This corridor is extensively instrumented for traffic flow simulation and control. Successful development and validation of such a simulation environment has allowed a number of particular advantages. It represents, to our knowledge, the first interactively simulated portion of specific urban freeway on any high fidelity simulator. It allows parallel testing of simulation versus actual driving conditions. It is capable of integration with a number of ongoing Mn/DOT, university, and commercial research projects. It provides a human factors testing facility that exceeds most capabilities that currently exist world-wide.

The research in traffic flow and safety has proceeded on two different tracks. The traffic flow research has focused on macroscopic aspects and aggregate behavior, while safety research has focused on the traveller's microscopic view of the transportation system. This dichotomy of research methodology has made it difficult to study many issues in intelligent vehicle highway systems in an integrated manner. In this project, we explore ways of facilitating research on problems which require integration of the two views of the transportation systems. In particular, we explore headup displays for conveying aggregate traffic information and exceptions to the drivers. We evaluate text based and graphic map based displays with fixed orientation as well as egocentric orientation. Our studies indicate that graphic displays are more effective than text based displays for the assimilation of information by drivers. Furthermore, our studies suggest that an egocentric map display allows drivers to assimilate and process information faster than a fixed orientation display.