Rolf Magnusson

Impact of Fine Materials Content on the Transport of Dust Suppressants in Gravel Road Wearing Courses

A significant problem when dust-suppressing agents are used on gravel roads is that they tend to leach during rainfall. The purpose of this study is to illustrate this problem by using laboratory s ...

Dust suppressants efficiency study : in situ measurements of dust generation on gravel roads

Dust suppressants were applied on fifteen 1 km long test sections at four sites in Sweden during three summer seasons with the objective to compare their relative efficiency and determine minimum application rates in Nordic climate. Dust generation from the test sections was measured both visually and by PM10 measurements. All products except lignosulphonate, sugar and bitumen emulsion showed acceptable efficiency. Chloride solutions were the most efficient. Results indicate the possibility to reduce application rates of chlorides by applying them as solutions instead of solids. The minimum application rate for a chloride solution was estimated at 0.8 m3/km, which is equivalent to a rate reduction of 50% by weight compared with traditionally applied rates of solid chloride. The results are expected to reduce life cycle costs for gravel roads and contribute to environmental gains by reducing the release of dust into the atmosphere and chemicals into the environment.

Road Barrier Repair Costs and Influencing Factors

This paper presents a study that examines repair costs for different road barrier types and factors that influence these costs. The analyses focused on w-beam and cable barriers used as median barriers. To some extent, pipe barriers, Kohlswa-beam barriers, and concrete barriers were also studied. The influencing factors included in this study were road type, speed limit, barrier type, and seasonal effects. A case study was conducted in four regions of the Swedish Road Administration. Data were collected from 1,625 barrier repairs carried out during 2005 and 2006. The results show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher along collision-free roads than along motorways and 4-lane roads. The results also show that the number of barrier repairs and the average repair cost per vehicle kilometer are higher for cable barrier than for other barrier types. No conclusion can be drawn regarding influence of speed limits on barrier repairs and associated costs as the result from the regions are divergent and not statistically significant.

Life-Cycle Cost Analyses for Road Barriers

This study aimed at developing a new approach for analyzing life-cycle costs for road barriers during the road planning and design process. A method called Activity-Based Life-Cycle Costing using the Monte Carlo Simulation was used to analyze and calculate the life-cycle costs. The results show a potential for increasing efficiency throughout the road planning and design process by minimizing the life-cycle costs of road components. The results also show that implementation of life-cycle cost analyses in the road planning and design process is possible, but difficult, mainly due to lack of relevant data.

In Situ Photographic Survey of Crack Propagation in Flexible Pavements

Traditionally, methods for measurement of cracks in roads are manual and subjective, which in turn means time-consuming and inaccurate. Generally, crack length and position data show accuracy of about one meter, which is insufficient when studying crack development of single cracks. Automatic methods exist, but their resolution is not high enough to study propagation of hairline cracks. The objective of this study is to develop and evaluate a new method for detection of hairline cracks using digital photographs. Yearly from 1998 to 2002, crack data have been collected on two in-service road objects, and the crack propagation has been studied. Cracks were extracted using digital image processing. Seasonal effects, such as healing, are also investigated. The rate of crack propagation shows high variations between different years, although the shape of the crack pattern obtained at different measurements is similar. Some crack segments visible in 1999 and 2000 disappear in 2001 and return at the same positions in 2002. The method is mainly suitable  for research purposes on limited areas.

Deterioration and rating of gravel roads: state of the art

ABSTRACT This paper presents a literature survey concerning the deterioration and rating of gravel roads. The methods for rating gravel roads in Sweden, Finland, Canada, USA, New Zealand and Australia are critically studied. The results show that a combination of traffic-dependent, geometric and physical factors govern deterioration, which in turn may lead to inadequate drainage capacity, potholes, rutting, corrugations, dust, loose gravel and frost damage. The literature review shows that the types of distress and the number of condition classes vary between different countries. Subjective assessment of road condition based on both verbal descriptions and photographs has traditionally been the method of inspection. On the basis of this literature study, a number of elements applicable to a new rating method are listed.

COMPUTERISED TOMOGRAPHY AS A TOOL FOR CRACK ANALYSIS IN ASPHALT LAYERS

ABSTRACT In this paper the application of X-ray Computerised Tomography (CT) as a tool for analysis of cracks in asphalt layers is described. CT is a non-destructive method typically used in the field of medicine and metallurgy. The method makes it possible to display the face of an internal surface at any depth of a sample, and has previously been used to study air void distribution and material displacement in asphalt pavements. In this study, asphalt cylinders from a typical Swedish road have been cored. It was found that about 3/4 of the cores contained cracks, which appeared at the surface but not at the bottom, indicating an initiation of the crack at the road surface (top-down cracks). No correlation was found between the type of crack and the position on the road with respect to the wheel path. The 3D crack pattern was also studied and the method proved to be useful for detecting internal cracks as narrow as 0.2 mm. Even if the method seems to be promising, considerable amount of further research is needed before a more general conclusion can be drawn about the usefulness of the method in road engineering. Examples in this connection are development of advanced technique, which makes it possible to detect more narrow cracks, and studies showing if cracks visible at the surface may propagate further down in the asphalt layers.

Statistical Analysis of Gravel Road Rating

This paper presents a statistical analysis of the method for gravel road rating used in Sweden. The findings are used to develop a new method. The study is based on the condition of about 20,000 sections of gravel road, each with a length of 100 m. The influence of climate zones, road authority regions, administrative provinces, traffic volumes, road widths, speed limits, and dust control material on the condition of the sections is studied. The analysis uses cross-tables combined with Goodness-of-fit test, as well as simple linear regression and logistic regression. The findings indicate that the method is not completely valid for accurately describing the condition of gravel roads. The results also show that the method is unsuitable for monitoring road condition. Therefore, certain adjustments are presented for making this method more accurate in describing the condition of gravel roads.