P G Jordan

East Sussex County Council

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John C. Young

University of Kentucky

B W Ferne

Transport Research Laboratory (United Kingdom)

Drc Cooper

Robert Morgan

St George's Hospital

S E Jenkins

Louisiana State University

Drc Cooper

Knorr-Bremse (France)

Peter Cairney

Australian Road Research Board

P B Still

Broadway

Rtn Goddard

J. Madison Porter

Loughborough University

Cooperative Institutions

University of Nevada, Las Vegas

Australian Road Research Board

Transport Research Laboratory (United Kingdom)

Loughborough University

Louisiana State University

Louisiana State University Agricultural Center

Indiana University School of Medicine

Indiana University – Purdue University Indianapolis

Walter Reed National Military Medical Center

Knorr-Bremse (France)

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Comprehension and visibility tests of some traffic control devices for local area traffic management

Australian Road Research Board (ARRB) Conference, 15th, 1990, Darwin, Northern Territory (1990)

Peter Cairney S E Jenkins P G Jordan

Standards Australia Committee MS/12 is currently developing a standard for Local Area Traffic Management (LATM). This report gives results of comprehensibility tests carried out on different versions of six signs for LATM applications, and visibility tests of marking patterns for road humps. Two or three versions of each sign were tested on independent groups of respondents. In the case of signs for 'One-way', 'Slow points', 'Shared zone', 'End shared zone', and 'Chicane', all versions performed about equally well, requiring that a choice be made among the alternatives on grounds other than comprehensibility. In the case of the 'Modified T-junction priority' and 'Left lane ends' signs, one version of each sign could be eliminated on the grounds of the tests, requiring a choice between the remaining alternatives on other grounds. A visibility meter was used to determine the recognition threshold for the different road hump markings, which subjects viewed monocularly at night. The tests allowed a consistent ordering of the five different patterns tested. Further testing was recommended in view of (1) possible confusion of the best-performing pattern with pedestrian crossing markings and (2) probable improvement of the performance of some of the other patterns with broader striping (A).

Visibility

Legibility

Confusion

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THE EFFECT ON TRAFFIC SPEEDS OF RESURFACING A ROAD

Drc Cooper P G Jordan John C. Young

On in-service roads, vehicle drivers may choose to drive more slowly over a surface that has deteriorated than they would over a more even surface. The report describes an experimental investigation to determine whether surface deterioration, typical of that found on major flexible roads in the United Kingdom, significantly influences traffic speeds. Speeds before and after the resurfacing or reconstruction of three test sites have been measured and analysed. The results show that, following resurfacing, traffic speed can increase by up to 2.6 km/h. The maximum increase was obtained by improving the profile of a pavement that had deteriorated to the worst state of irregularity expected on major flexible roads in the UK. Changes in surface texture levels are shown to have no significant effect on traffic speed.(a) (TRRL)

Traffic speed

Road surface

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9 Measurement of road surface shape using a laser sensor

P G Jordan

A contactless laser sensor has been developed that is capable of measuring vertical height from the road surface up to 3300 times per second. It has a resolution of 0.282 mm over its working range of 72 mm, which is centred at a distance of 270 mm from the sensor. The sensor has been employed in the development of computer controlled systems for measuring, at traffic speed, the longitudinal profile, the macrotexture and the wheel-track rutting of a road surface. The operation of the sensor and its applications to the measurement of surface shape are described. (Author/TRRL)

Laser Scanning

Road surface

10.1680/sihace.01091.0011

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Fewer stop signs: more safety, less cost

P G Jordan Robert Morgan

Stop and Give Way signs are the most commonly used traffic control devices. They have been widely used at intersections throughout Victoria to override the give-way-to-the-right rule for the last fifteen years. However, over this period a tendency has developed amongst engineers to install Stop signs in preference to Give Way signs, regardless of site conditions, because of an inherent belief that using Stop signs results in greater safety than using Give Way signs. The resulting intersection control system has encouraged disobedience amongst motorists who see little reason to stop at most Stop signs. The disturbingly poor compliance with Stop signs has implications for critical intersections (where stopping is vital for safety) and for motorists' attitudes to traffic control devices in general. In 1988 and 1989 the Roads Corporation's predecessor organisations (the Road Traffic Authority and Road Construction Authority) and the Local Government Engineers Association, with support from the Victoria Police, Australian Road Research Board and Royal Automobile Club of Victoria reviewed current guidelines, warrants, and practices for the installation of Give Way and Stop signs. A new set of guidelines based principally on revised sight distances has been developed for use in Victoria. Implementation of these should result in a reduction of approximately 16,000 Stop signs and lead to greater driver respect for the remaining Stop signs. The background to the new guidelines is detailed in this paper. At the same time, a review has been undertaken of the need to use control signs at T-junctions following introduction of the T-junction rule in 1981. Guidelines have been established which will halve the number of sign controlled T-junctions. Savings to State and Local Government through this change alone are expected to exceed one hundred thousand dollars per annum (A).

Warning signs

Vital signs

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MEASUREMENT OF RUT DEPTHS IN ROAD SURFACES BY THE TRRL HIGH-SPEED PROFILOMETER

Publication of: Transport and Road Research Laboratory (1982)

P G Jordan P B Still

The existing method of measuring deformation in the wheel paths of roads in the UK is by straightedge; it is slow and is hazardous on busy roads. A safer and faster method of measurement using the new TRRL high-speed profilometer has been developed at the laboratory. This report describes the method of measurement and the evaluation of the factors affecting the accuracy of measurement. Comparison of the high-speed and existing method of measurement show agreement to within 2mm on major roads and within 3mm on other roads. The difference between the measurements is caused in part by the sampling error of the straightedge method and in part by the operator in controlling the line of measurement of the high-speed system. Repeatability of meaurement is found to be such that on average 80 per cent or more of the repeat measurements differ by 1.5 mm or less. Criteria for rut depth derived from existing maintenance criteria are presented for use with the high-speed system. Alternative and less costly equipment than the profilometer that would measure rut depth and surface texture is briefly described. (Author/TRRL)

Repeatability

Road surface

Measuring instrument

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Some landslipping encountered during construction of the A40 near Monmouth

Quarterly Journal of Engineering Geology (1985)

K. R. Early P G Jordan

Summary The A40 is a trunk road constructed in 1964 on sidelong ground beside the River Wye, about 1.54 km, north of Monmouth. The sidelong ground comprised a dip slope of 30-35° dip in the Brownstones of the Devonian which consist of sandstones with subordinate mudstones. On investigation it was found that three ancient landslips existed which the road had to cross. One, at Chapel Farm, was estimated to be probably first active in post-glacial times; another at Whipping Green, was estimated to have occurred at about Roman times; and the third, at Vaga, was estimated to have occurred sometime betweeen the other two. Conventional engineering had not succeeded in crossing the sidelong ground without re-activating these slides. Total failure had occurred at Chapel Farm Slip and the inter-carriageway slopes had failed where the road crossed Whipping Cross Slip. After a full investigation the road was re-designed more or less on its original route using light-weight fill for embanking and a massive berm at Chapel Farm, and chiefly by using replacement counterforts on the cut slopes at Whipping Green Slip. Sand drains were used through the Wye alluvium below the berm where it was founded over the alluvium. There was also a large area of ‘partly slipped rock’ which although it did not constitute a landslide, threatened the road from above and was far too large and complex a mosaic for treatment or removal. It was decided to build a rock fill revetment at the toe of this mass and then to monitor it for movement on the assumption that only one or possibly two parts of the mosaic could move at any one time. During the investigation a fairly exhaustive laboratory testing programme was carried out and a detailed study was made of the behaviour of groundwater. It is now 1984, some 20 years after construction of this section of road and there has been no trouble of any kind.

10.1144/gsl.qjeg.1985.018.03.03

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HIGH-SPEED ROAD MONITORING SYSTEM

Transportation Research Record Journal of the Transportation Research Board (1983)

P G Jordan J. Madison Porter

A high-speed road monitoring system has been developed at the Transport and Road Research Laboratory. It consists of four laser sensors mounted on a 4.5 m-long beam that is supported by a two-wheeled trailer towed behind a small van. Measurements are made by the configuration of laser sensors under the control of a computer system located in the vehicle behind which the trailer is towed. Longitudinal profile, wheel-track rutting, and surface macrotexture are measured as the system travels over the road networks in the normal traffic stream; provision is being made for the measurement of road crossfall, gradient, and horizontal curvature. The principles of system operation in the different measurement modes are described and illustrated. Use of the measurements made by the high-speed system in studies of the effects of unevenness on the road user and in detecting structural deterioration of roads is described. Its potential for use in making surveys of the road network at a relatively low cost, locating areas of distress, and guiding the deployment of other, more specialized equipment is discussed within the context of the development of a cost-effective maintenance management system. (Author)

Trailer

Road surface

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THE REPRODUCIBILITY AND REPEATABILITY OF THE PSV DETERMINATION

L W Tubey P G Jordan

This report describes, and gives the results of, an experiment designed to study the reproducibility and repeatability of the polished-stone value (PSV) determination when carried out according to the procedure given in BS 812 : 1967. Repeatability and reproducibility estimates were obtained from analyses of: (A) measured test results, and (B) test results 'corrected' by a factor based on the values obtained on Enderby control specimens. The analyses showed that the repeatability and reproducibility estimates on the measured test results for a single measurement were 4.9 and 6.0 units respectively, but for the 'corrected' test results both estimates were reduced to 4.2 units. These results confirmed the value (six units) for the reproducibility of the test which is quoted in the current edition of BS 812, but showed that the incorporation of a 'correction' technique into the procedures would appreciably improve its precision.

Repeatability

Round robin test

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ROAD PROFILE DETERIORATION AS AN INDICATOR OF STRUCTURAL CONDITION

Research report - Transport and Road Research Laboratory (1989)

P G Jordan Drc Cooper

Longitudinal profile and rut depth have been monitored over a period of six years on over one thousand, twenty metre long test sections spread over motorway and trunk road sites using the TRRL high-speed road monitor (hrm). Trends in profile with time were compared with assessments of structural condition using visual inspection, and deflection. Changes in longitudinal profile for features of less than three metres wavelength over a period of two years were found to reflect significant pavement deterioration as assessed by visual inspection. Also, this measure of profile change was found to increase significantly with a decrease in the residual life of pavements as estimated from deflection under a rolling wheel. Criteria, based on the proportional change in longitudinal profile have been defined for use in detecting significant pavement distress in fully flexile pavements and those with a lean concrete roadbase. The application of these criteria to surveys made with the hrm is described and the combination of machine and criteria is shown to provide an efficient and economic means of locating deterioration in the road network. (Author/TRRL)

Visual inspection

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Citations (7)

Las Vegas Springs Preserve Project

ACI Concrete International (2007)

P G Jordan Mark Criswell

Las vegas

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