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DTFH61-81-C-00057, This report documents an evaluation of driver characteristics and how they affect highway design and traffic operations standards. The study involved the identification of all standards which are a function of a driver characteristic; the development of a population profile for each characteristic; calculation of the sensitivity of each standard to realistic changes in a driver characteristic; and recommendation of changes to current specification values for driver characteristics and to standards. The study found generally inadequate consideration of driver characteristics in the development and application of current standards. The report provides detailed examination of the driver characteristics perception-reaction time, driver eye height, vision, information processing capacity, age, sex, and pedestrian walking speed. The report recommends modifications to several design and operations standards which currently do not accurately depict the actions required of the driver in a particular situation or do not adequately compensate for the needs of the driving population.

DTFH61-84-C-00082, Bridge deck design, at present, often includes costly bridge deck drainage provisions. Many bridge engineers have questioned the need for bridge deck drainage appurtenances, at least to the extent presently included in typical bridge design. This document presents criteria to determine if bridge drainage scuppers and drains are required. A design nomograph allows a rapid decision to be made. A key variable, design rain intensity, is analyzed: the rational method is reviewed and new methods for setting design rain intensity are presented that consider hydroplaning and driver vision. Regardless of the need for scupper, bridge end drainage is necessary, and methods are given. If scuppers are needed, this document provides sound drainage design practice for bridge drainage. This document, plus HEC No 12 and NCHRP synthesis No 67 provide very complete reference material for bridge drainage. Good engineering judgment is still a factor for locating scuppers. For example, if theoretical scupper spacing is 150 ft and piers are 100 ft apart, the scupper spacing should be set at 100 ft to accommodate vertical downpipes and provide adequate support.

DTFH61-92-C-00172, This report documents an investigation into the feasibility of using accident data to derive estimates of the rate at which errant vehicles unintentionally encroach into the roadside on level, tangent sections of two-lane rural roads. In addition, issues related to estimating the percentage of unreported accidents were also investigated. The report discusses results from the literature and an analysis of hit-utility-pole accident cases from the National Accident Sampling System (NASS). A pilot study involving 56 km (35 mi) of tangent, two-lane rural road sections in Idaho is also documented. For that pilot study, detailed roadside data were collected and accident and traffic data were obtained. Based on an analysis of that data, the resulting encroachment rate estimates were determined to be of the same order of magnitude as the encroachment rates that had been developed from previous research. It was concluded that the methodology is feasible, although it is limited by the current state of the knowledge with respect to data on the trajectories of vehicles involved in run-off-the-road and hit-fixed-object crashes. An experimental plan for future research that would produce improved estimates of roadside encroachment rates is also presented. Because the plan depends on the availability of detailed sign maintenance and roadside inventory data in electronic media, it is recommended that the plan not be implemented immediately. When and if it is implemented, the latest results from other research on trajectory data should be integrated into the plan.

DTFH61-91-R-00069, One of the identified truck accident types that occur on curved exit ramps at interchanges is truck rollover. A truck will overturn or rollover if the lateral acceleration imposed upon it as it travels around a curve of a certain radius and superelevation is greater than allowable given its loading condition. Also, there is a speed at which rollover will occur. This report deals with an automatic warning system to prevent truck rollover. Within the study, three different options were identified and evaluated for feasibility. Of the three, the option selected for further definition and cost-effectiveness analyses was an inroad detection/warning system. The system consists of two detection stations upstream of the curve with the combined ability to detect a truck speed, weight, and height threshold. The warning system is a combination of a static warning sign and a fiber-optic warning message sign, which would be activated if the controller determined that the truck would be operating at the rollover threshold speed or faster by the time it reached the point of curvature. This report provides the details of the design, its costs, and its cost-effectiveness. Also, design plans and specifications were prepared for three installations on the Capital Beltway in Maryland and Virginia.

DTFH61-84-C-00082, A practical method for determining the road surface drainage system design with the theoretic Lowest Total Economic Cost (LTEC) is developed. The LTEC design determines the design rain which, when used in a rational-based design context, will yield the most economic choices of gutters, inlets, and laterals considering both construction costs and risk costs. The data needed to find the LTEC design rain are: the number of rains per year, the design gutter flow, duration of average rainfall, runoff coefficient, drainage area, inlet and lateral costs, capital recovery factor, and a traffic loss coefficient. A nomograph and data selection guidance are provided as design aids. Three case studies are presented in an appendix. The method, based on minimizing traffic delay costs, applies to freeways, arterials, and major collectors; local streets with low traffic may be excluded.