0 1998 OPA (Overseilr Publ~rhcrr Asrocintion) N.V. Rcprintr uvilihble directly from ths publisher Pvblirhcd by lien* under Photocopying pcrmitlcd by liccnsc only the Gordon und Breach S c m a Publirhcrr impnnt. The automated highway system (AHS) is "the application of vehicle/highway automntion technology to provide signficunr improvements in traflic safety, throughput, travel times, comfort, convenience, energy, and [the] environmenl." Under a contract with the Federal Highway Administration to investigate human factors aspects of the design of the AHS, 14 experiments and several analytical tasks have been conducted. The results of the experiments and analytical work on automated-steering failures are reviewed, followed by a summary of the implications of that work for automated highway systems. Then, several critical human Pdctors research issues -from a list of 62 developed during the contract -are presented and discussed.

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Signalized intersections that interface with light rail transit (LRT) pose a unique challenge to traffic operations and safety. Although progress toward mitigating light rail vehicle–motor vehicle crashes has been made, many agencies still face safety issues at these intersections. Few empirical studies of the effectiveness of the safety measures currently being used have been conducted. Safety measures have not been tested with drivers; rather, the measures they have evolved over time through practice. The objectives of this research were to assess driver comprehension and to explore drivers’ perceptions and opinions of a variety of traffic control devices (TCDs) that were or that might be used at signalized intersections that interface with LRT. The research approach was to present simulated scenes to drivers with a variety of intersection scenarios and TCDs in a focus group setting. The results showed that drivers had preferences for TCDs at these intersections. Although existing TCDs are understood and generally liked, ongoing issues with safety suggest that improvements can still be made. The use of green arrow signal displays or supplemental pavement markings could improve driver situational awareness at some intersections. Enhancements to the existing Manual on Uniform Traffic Control Devices W10-7 (i.e., train icon) activated blank-out sign, such as adding the word “train” or alternating the train icon with the no left turn icon, could result in increased driver compliance. Finally, providing an active warning device on the cross street, such as the W10-7 sign, could increase safety by making drivers and pedestrians more aware of the arrival of a train.

No abstract

The essential elements of signs with lane use and destination information combined were evaluated to determine the element or combination of elements best comprehended by road users. The sign elements in this study were evaluated only for overhead-mounted guide signs on approaches to multilane conventional intersections. The research team identified existing standards in the Manual on Uniform Traffic Control Devices (MUTCD) for similar signs or related sign elements that might already have been applied by states to communicate lane use and destination information combined. The team also identified any elements that might have been relevant but were not yet included in MUTCD. This information was used to select the following variables for use in combination on signs with lane use and destination information: lane designation, construction type, destination direction, arrow type, and vertical separator lines. Combinations of these variables were then used to develop 18 experimental signs. Most alternatives were well understood by the research participants. Signs with single-lane designations were understood significantly better than signs with shared-lane designations. The study shows that when overhead-mounted guide signs with lane use and destination information combined are designed for approaches to multilane conventional road intersections, the amount of information and sign complexity must be kept low, especially for signs with information on shared lanes, in which information for multiple shared lanes can be confusing to drivers. The study shows no difference in comprehension on the basis of the use of vertical separator lines, arrow type, or construction type; however, in some situations these designs can quickly become complex.