A brief description is given of a field experiment to determine the optimum use of discrete retroreflective delineation devices around short-radius curves. Seventeen different combinations of retroreflective raised pavement markers and post-mounted delineators were trialled around a 3 km circuit set up for the purpose. Results showed that driver behaviour and confidence improved as the amount of delineation increased, that a combination of RPM's and PMD's were better than either used alone, that lane-keeping behaviour is primarily determined by the use of RPM's.

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Performance of traffic signs in Australia

F R Gennaoui S E Jenkins

The paper presents the factors affecting sign performance at night. It also includes a report on the of signs based on a literature review, and the findings of a pilot survey with respect to terminal values, the methodology of the field surveys is described together with the terminal values of traffic signs in different environments. The major conclusions from this preliminary analysis can be summarized as follows: (1) The photometric performance of Class 1 sheeting drops to 72 per cent of its original value after about 13 years, and the photometric performance of Class 2 sheeting drops to 50 per cent after about 9 years. (2) Cleaning the signs results in better performance at any point along the life curve of the sign. (3) The degradation of signs changes the contrast ratio of the legend to background. (4) The nighttime survey resulted in mean terminal values ranging from 2 to 21 CIL/m**2 with a range up to 55 CIL/m**2. Because of the difficulty of the task in the field, these estimates are likely to be of signs which are well beyond their terminal value.

Value (mathematics)

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A rational basis for safe limits for window tinting in automotive glass

S E Jenkins

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Proceedings of a seminar on 'street lighting and safety' held at chisholm institute of technology, 23 November 1982

M Armour S E Jenkins

This report is the proceedings of a seminar on 'street lighting and safety' held at chisholm institute of technology, 23 November 1982. The first session discussed the relationship between the provision of street lighting and accidents. The expected benefits from either the provision of new lighting or upgrading existing installations was considered, and the benefits of lighting on different road classes was also discussed. The effects of recent reductions in lighting as an energy saving measure was reviewed. The second session discussed the visual needs of drivers and how measures of visual performance and comfort can be used to arrive at a specification of road lighting installations in terms of the light technical parameters. The effects of the luminaire, the installation geometry and road reflection characteristics on the light technical parameters were discussed. The third session dealt with the treatment of two problem areas, the lighting of pedestrian crossings and the specification and treatment of wet roads (a).

Electric light

Smart lighting

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Consideration of the effects of background on sign conspicuity

Applied Ergonomics (1984)

S E Jenkins

10.1016/0003-6870(84)90225-4

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The performance of modern retroreflective material in the road traffic environment I: visual acquisition and sign legibility

S E Jenkins

The use of retroreflective sheeting has been primarily driven by the photometric performance of the sheeting with little regard to assessing the effectiveness of various sheeting types in meeting drivers' signing needs under different road traffic scenarios. The advent of microprismatic sheeting allows for much greater freedom in the design of the photometric performance of the sheeting. The questions of where and whether to use microprismatic sheeting has generated increased confusion in the State Road Authorities and Local Governments and has become a major issue within Standards setting bodies. The objective of this paper is to provide some guidance as to the performance of signs made from the different types of sheeting and how each should best be used to benefit the driver. Two partial models of visual acquisition of sign information are proposed that are relevant to the retroreflective performance of traffic signs. They are a visual scanning-type model and a visual conspicuity-type model. The major consequence of the two models for retroreflective sheeting is that they operate over different distance ranges. A model of the sign luminance as a function of distance from the sign is proposed based on a review of previous legibility studies. The model suggests two criteria, one for an adequate sign luminance that will meet driver requirements for most situations and one for optimal sign luminance that will cater for high luminance complex surrounds, older drivers and sign conspicuity.

Legibility

Confusion

Headlamp

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Terminal values of road traffic signs

Australian Road Research Board (ARRB) Conference, 13th, 1986, Adelaide, Australia (1986)

S E Jenkins F R Gennaoui

For a traffic sign to be effective it must at least be able to be detected, read and understood by the road user. The qualities of a sign which influence its ability to attract attention and be legible are its external contrast with its immediate environment and the internal contrast between legend and sign background. The values of these contrasts are a function of the type and colour of sign material. The materials have retroreflective properties and so can perform adequately at night as well as the day. However the materials will degrade with time and there will come a point at which the external and internal contrasts of the sign will no longer be adequate. Invariably this will happen to the night time performance first. The state road authorities are now seeking quantitative information which will determine the minimum photometric characteristics of a sign below which it will be ineffective. This determination has formed the basis of an ARRB research proposal which is outlined briefly. Any recommended value of the photometric efficiency of a sign will depend on the function of the sign and distance at which the driver will use the sign. The results of a pilot study which measured the retroreflective properties of signs judged subjectively to be ineffective are reported and compared with those found in the literature (a).

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