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Condition assessment of road equipment: State-Of-The-Art
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
2008 (English)In: The Baltic Journal of Road and Bridge Engineering, ISSN 1822-427X, Vol. 3, no 2, 84-92 p.Article in journal (Refereed) Published
Abstract [en]

Road equipment is used for increasing safety and comfort in traffic. There are 5 main groups of equipment: road lighting, fences and barriers, vertical signs, horizontal signs and traffic signals. Common for all road equipment is that, once they have been installed on the road, the performance must be maintained. Condition assessment is an important tool for determining the maintained degree of performance. Generally, there is a large number of equipment along a road. This means that a measurement method must be fast and practical to use. Even so, not all equipment can be measured, but a sample must be chosen from the population. In other words, condition assessment needs both sampling and an appropriate measurement method. In practice, sampling in-situ can be difficult to perform. Consequently, it might be necessary to deviate from complete randomness when sampling. However, it is important that sampling is carried out in such a way that no systematic errors are introduced. A physical measurement method aimed for condition assessment should preferably be mobile. Unfortunately, only a few mobile methods are described in the literature and, among these methods, solely one physical method has been used for assessment (road marking retroreflectivity characterization). Results from such studies have been published in USA and the Nordic countries. Although the lack of mobile instruments, condition assessments of street lighting, rails, noise shields, glare shields, road signs, raised pavement markers and traffic signals have been documented. Such studies have been carried out using stationary instruments or by a subjective judgement. It is known that quality control improves performance, which has, for example, been documented in a Swedish 6-year study on road markings. Consequently, if checks of road equipment are carried out regularly, there is a reason to believe that this control would improve the road equipment performance, which, in turn, would be a benefit, not only for the road keeper but also the driver. Therefore, development of mobile instruments aimed for all types of road equipment is desirable.

Place, publisher, year, edition, pages
2008. Vol. 3, no 2, 84-92 p.
Keyword [en]
road equipment; road lighting; barrier; road sign; road marking; traffic signal; condition assessment; retroreflectivity; visibility
National Category
Civil Engineering
Identifiers
URN: urn:nbn:se:kth:diva-8086DOI: 10.3846/1822-427X.2008.3.84-92ISI: 000257423500006Scopus ID: 2-s2.0-70349229860OAI: oai:DiVA.org:kth-8086DiVA: diva2:13314
Note
QC 20100824. Uppdaterad från submitted till published (20100824).Available from: 2008-03-10 Created: 2008-03-10 Last updated: 2010-08-24Bibliographically approved
In thesis
1. Evaluation of Road Equipment with Emphasis on Condition Assessment
Open this publication in new window or tab >>Evaluation of Road Equipment with Emphasis on Condition Assessment
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This doctoral thesis deals primarily with condition assessment of road equipment. The road equipment concept is defined by five main groups, road lighting, fences and barriers, vertical signs, horizontal signs and traffic signals, respectively. Of these groups, road markings, street lighting and barriers of three-lane roads have been studied more in detail.

A state-of-the-art, comprising information obtained by comprehensive literature studies on condition assessment of road equipment is presented. Comparably few fundamental studies were found, which, to some degree, can be explained by the lack of suitable physical measurement methods. However, in the case of road marking retroreflectivity, mobile instruments have been developed, and research published in this area is relatively comprehensive. Furthermore, although not based on mobile measurements, several studies on assessments on performance of road sign sheeting have been published.

The experimental part of the thesis is divided into four studies, of which two are dealing with mobile measurement of wet road markings and street lighting, respectively. One of the studies concerns condition assessment of road marking performance accomplished in the Nordic countries. Finally, one study comprises risk analysis related to crashes into the barriers on three-lane roads. At road equipment condition assessment, mobile measurement methods are preferable compared to stationary methods. However, many relevant parameters are tricky to measure at speed. One example in this connection is characterization of performance of wet road markings, which has to be based on one or more parameters obtained by measurements on dry surfaces. Results presented in this thesis indicate that retroreflectivity and skid resistance of wet road markings can be predicted based on retroreflectivity and macro-texture of dry road marking.

For traffic safety, street lighting is important. The performance of this type of road equipment is in most cases described in terms of luminance of the illuminated road surface. However, luminance measurements are tricky and time-consuming and not useful for condition assessment. On the contrary, measurement of illuminance is easy to carry out and can be performed at speed. One part of the thesis describes how road surface luminance in street lighting can be estimated based on illuminance and reflection properties of the road surface. With the purpose of comparing road marking performance in the Nordic countries, condition assessment using mobile measurement equipment was accomplished in 2002 and 2003. In each of the five Nordic countries, a number of roads were chosen for measuring retroreflectivity. The study showed that the retroreflectivity of edge, centre and lane lines was poor in some countries, but, at least regarding edge lines, this shortcoming could be compensated by use of wide, continuous lines. In other words, the visibility of longitudinal road markings was approximately equal in the different countries.

The purpose of the risk analysis performed on three-lane road barriers was to estimate the influence of the time-period between initial crash and repair on the risk of a secondary accident. The result showed that, especially in winter-time, time-reduction means reduced risk of secondary accidents.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. ii, 33 p.
Series
Trita-VT. FR, ISSN 1650-867X ; 08:02
Keyword
Road equipment, Condition assessment, State-of-the-art, Mobile measurement, Road marking, Road sign, Post delineator, Traffic light, Street lighting
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-4665 (URN)
Public defence
2008-04-02, Sal F3, KTH, Lindstedtsvägen 26, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100824Available from: 2008-03-10 Created: 2008-03-10 Last updated: 2010-08-24Bibliographically approved

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