Tag Archives: traffic safety

1041–1052 M. Khrapova
Determining the influence of factors on retroreflective properties of traffic signs
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Determining the influence of factors on retroreflective properties of traffic signs

M. Khrapova

Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ165 00 Prague, Czech Republic
Correspondence: khrapova@tf.czu.cz

Abstract:

One of the distinguishing features of future autonomous cars is the ability to take into account and communicate with traffic infrastructure. Thereby detection and recognition of vertical traffic signing is an obvious requirement. Automatic recognition of traffic signs allows to check driver’s reaction time, if it is necessary to react, and in that way to contribute to and increase the road safety. It is especially important in the darkness when the retroreflective sheeting materials on the traffic signs help to increase visibility. Unfortunately, environmental conditions around the traffic signs exert considerable influence on the sign’s surface and alter their retroreflective properties. Many scientists explored different impacts on retroreflective properties of signs. Some impacts attracted more attention (such as detection distances and deterioration with age), some impacts were studied by several scientists only (such as dew and frost) and some factors were even omitted at all (e.g. the temperature during measurements of in-service signs). The paper is focused on the impact analysis of insufficiently explored factors influencing retroreflective properties of traffic sings. The findings of this research can support the development of further experimental research and could become a basis of reliable traffic signs usage on modern and smart roads.

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1635-1644 J. Kreicbergs, G. Zalcmanis and A. Grislis
Vehicle in-use tyre characteristics evaluation during winter driving training
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Vehicle in-use tyre characteristics evaluation during winter driving training

J. Kreicbergs*, G. Zalcmanis and A. Grislis

Riga Technical University, Faculty of Mechanical Engineering, Transport and Aeronautics, Department of Automotive Engineering, 6k Ezermalas street, LV1006 Riga, Latvia
*Correspondence: juris.kreicbergs@rtu.lv

Abstract:

After the substantial number of fatalities in road traffic increase with the start of icy 2014–2015 winter conditions in Latvia drivers have been offered complimentary winter driving training. Having numerous drivers with their cars performing the same braking actions on restricted and safe test ground gave a good opportunity for evaluating driver skills and vehicle in-use tyre condition. Tyre age and tread depth were measured and driving instructions have been given to more than a thousand participants. Instrumented braking and manoeuvring measurements were made for thirty cars. The equipment included GPS receiver and decelerometer. Measurement results have been compared against physical observations and hints given by professional driving instructors. The comparison indicated that although the suggestions given to drivers by professional instructors clearly contribute to safer driving, the visual evaluation without measuring may lead to various errors in messages conveyed to drivers. The most questionable statement was about the influence of the vehicle mass on braking distance. The investigation did not show essential vehicle mass influence on tyre grip and correspondingly on braking characteristics. Tyre tread depth effect on braking performance demonstrated the relevance of technical requirements for winter tyres. The advantage of using public training for winter tyre in-use experiments is lower cost for getting tyre samples with various technical conditions. The disadvantages are the different skills of car owners, the need for individual instructions and the necessity to reckon with the training format, the limited choice of the testing variables and substandard conditioning of the road surface. The tests gave valuable information for further training sessions and coming winter tyre tests.

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