This dissertation is compiled of the findings of several phases of a detailed research study that was aimed at investigating the Skid Resistance phenomenon. In the first phase of the dissertation research a study was performed to evaluate the different factors that influence frictional measurements obtained using the Dynamic Friction Tester (DFT). A temperature calibration factor that would account for temperature effects on DFT readings and IFI computations was developed. In addition, other variables that also affect the friction measurements obtained using the DFT are identified. In the next phase of the dissertation research the effect of pavement roughness on the Skid Resistance was investigated. The variation of the normal load and its nonlinear relation to SN was used to explain lower SN values measured on relatively rougher surfaces. The feasibility of using the International Roughness Index (IRI) and the Dynamic Load Coefficient (DLC) as predictors of the reduction in SN due to pavement roughness was also investigated. In the final phase of the dissertation research an in-depth investigation was carried out to better understand the principles underlying the concept of the International Friction Index (IFI), and specifically the role played by the Speed Constant ( Sp) parameter in the IFI computations. The parameter Sp dictates the speed variation of the wet friction measurements taken on a given pavement surface. The results of the current investigation suggest the revision of the procedure for computation of the Sp parameter to incorporate device specific properties. Furthermore, the incorporation of vehicle characteristics in the Sp parameter computations would help address a well known deficiency of the IFI, which is the inconsistent FR60 (predicted friction at 60 km/h) obtained from the friction values measured at two different slip speeds on the same surface. This study also showed that the modification of the Sp parameter reduces significantly the slip speed dependency of the device calibration parameters A and B. Finally, a modified IFI procedure that incorporates device specific slip conditions is presented. The modified IFI procedure showed consistently better predictive capability than the conventional ASTM procedure on all the different devices considered in this study.

Darbo tikslas - atliekant arimo darbus nustatyti traktoriaus buksavimo, degalų sąnaudų bei padangų temperatūros kitimo nuo jo balastavimo ir oro slėgio padangose dydžio priklausomybes. Darbe nagrinėjama balastinės masės ir oro slėgio padangose įtaka traktoriaus eksploataciniams rodikliams. Pateikiami eksperimentiniai tyrimai, kurių metu, keičiant balastinės masės ir oro slėgio padangose reikšmes, buvo matuojamos degalų sąnaudos, varančiųjų ratų buksavimas bei padangų temperatūra. / Work theses - at tillage work investigate tractor wheel skid, fuel consumption and tire temperature dependence from tractor ballast weight and tire pressure. This study investigates a ballast weight and tire pressure influence on tractor’s unit performance. Experimental studies have been performed by changing the weight of ballast and tire pressure values, fuel consumption, wheel skid and tire temperature were measured.

The responses of invasive exotic plant species (IES) to silvicultural treatments one growing season after timber harvesting were examined in the Cumberland Plateau region of Southeastern Kentucky. Treatments included a commercial deferment harvest and unharvested control applied to five watersheds within University of Kentucky’s Robinson Forest. The effects of harvesting were compared between treatments and between preharvest and postharvest samplings. The spatial distribution and abundance of targeted IES throughout forest sites and trail systems were calculated from several sampling schemes. Additional analyses were performed to quantify forest disturbances derived from harvest activities to determine the relationships between soil, light levels, and other environmental characteristics and IES cover. Logistic and multivariate analysis techniques were used to analyze differences in IES distribution between pre-harvest and post-harvest units to relate post-harvest IES to microsite conditions. Microsite conditions within the forest and along the trail system proved important for explaining the presence and distribution of IES. Timber harvesting caused a significant increase in both Ailanthus altissima and Microstegium vimineum within harvested areas. However, many other identified IES did not initially respond to disturbances. Throughout the treatment units, species were influenced by disturbance type and intensity, as well as proximity to reclaimed surface mined land.

This paper describes a study designed to determine average labor and machine times required to implement erosion control and revegetation best management practices (BMPs) for skid trails in Kentucky. Labor and machine activities were recorded for 14,400 feet of skid trail on 10 nonindustrial private logging sites. Water bar construction and reshaping activities such as filling ruts and berm removal were filmed continuously with a video camera and then analyzed using time-motion study techniques. Labor activities for revegetation such as seeding and application of fertilizer were also timed. The average total machine time for retirement activities per 1000 feet was 51 minutes for sites using dozers and 52 minutes for sites using skidders. The average water bar construction time using a bulldozer was 1.5 minutes (n=112) while the average construction time using a skidder was 3.5 minutes (n = 21). The average amount of labor time required to seed 1000 feet of skid trail was 23 minutes (n = 5). Three methods of water bar construction were observed and analyzed to identify differences among them. While there were significant differences among the three methods, the data suggest that skid trail percent slope may have the greatest effect on water bar construction times.

Thesis (D. Min.)--Westminster Theological Seminary, Philadelphia, 1993. / Includes bibliographical references (329-329 leaves ).

xvi, 206 p. A print copy of this title is available through the UO Libraries under the call number: KNIGHT HV4504.K56 1982 / This study will focus on changes that skid row is experiencing. Following an introductory statement which defines skid row and reviews the area historically, an examination of skid row evolution on a national basis is presented. Specifically, this involves a comparative analysis of thirty-one skid rows representing all regions of the United States. Each skid row is examined as to its 1950, 1968, and 1979 size. and location. Much of the information for this analysis is based on responses to questionnaires and census data. With few exceptions, skid rows have changed substantially from 1950 to 1979. Most have declined significantly in size or relocated to new sites in the central business district. Almost all the cities surveyed have retained a skid row, in some form, over the thirty years studied. A closer view of skid row evolution and change is presented utilizing a case study of Portland, Oregon. Portland was selected for study because it is fairly representative of skid rows in general. It has had a skid row for approximately a century and its process of establishment, growth, and decline through the years has followed a pattern which is typical of other skid rows studies throughout the United States. For example, the current "0ld Town" trend occurring in some skid rows is also happening to Portland1s skid row. Sanborn Maps, city directories, field observations, and census tract reports provide land use data for Portland. Despite the efforts of planners and others to remove skid row from the landscape, with rare exceptions it has existed as an urban phenomenon for at least a century to the present day. / Adviser: Everett Smith

Similar to most other large North American cities, that area of Vancouver which at the beginning of the present century was at the hub of a young and vigorous regional economy, is now playing host to the castoffs of our society made up of those who are suffering from physical and emotional ill health or have fallen by the wayside because of poverty and lack of skills and education. The social agencies serving the area recognize that by and large their efforts are only of an emergency nature and leave the basic problems untouched. A comprehensive program to deal effectively with the problems of skid road requires resources beyond the means of these agencies and will require extensive support, financial and otherwise, from civic and senior governments. A number of the agencies serving the area have been instrumental in bringing the dilemma to the attention of civic authorities and in recommending remedial and preventive action. Studies and programs which have been undertaken on Skid Road in the United States, point the way to a solution of similar problems in Vancouver. At the same time research on the subject is still relatively limited, and much more needs to be known, especially of the situation as it exists at the local level. The present study is intended to add to the fund of basic knowledge on Skid Road in Vancouver. This is a necessity if effective planning and action are to take place. In the introductory chapter Skid Road is portrayed in terms of its historical and present physical and social characteristics. A review of two recent studies on Skid Road in Vancouver familiarized the reader with some of the problems of the area and suggests possible ways of coping with these. A few observations on newspaper coverage of the area conclude the chapter. In Chapter II a summary of several studies and projects on Skid Road in the United States offers a means of comparison to the local scene. The second half of the thesis focuses on an examination of the problems and social policy of Skid Road in Vancouver, as seen by representatives of social agencies serving the area and the clientele served. The purpose of the study, its scope, and the materials and methods used, are outlined in greater detail. In chapter 4 the research data are classified and presented in table form where appropriate. A brief analysis of the data is also presented. The final chapter contains observations on the research project and its findings as a whole. The thesis ends with a number of recommendations and conclusions on the basis of the findings. The study was intended primarily as a further exploration of the problem area. Definite conclusions were not expected. At the same time, the following observations deserve closer consideration. It was felt that particular attention be given to the establishment of: a) a multipurpose agency in the Skid Road area b) a variety of hostels and halfway houses located throughout the city c) a coordinating body to deal with Skid Road problems / Arts, Faculty of / Social Work, School of / Graduate

The output of this diploma work (dissertation) will be design of a construction for a tester enabling simulation of riding a vehicle with mounted snow chain in winter season on road without snow. The result of testing will be abrasion of single link of the chain caused interaction with surface of road and strength test of weld link e.g. when is pass gravelly surface.

Pavement roughness has been found to have an effect on the coefficient of friction measured with the Locked-Wheel Skid Tester (LWT) with measured friction decreasing as the long wave roughness of the pavement increases. However, the current pavement friction standardization model adopted by the American Society for Testing and Materials (ASTM), to compute the International Friction Index (IFI), does not account for this effect. In other words, it had been previously assumed that the IFI's speed constant (SP), which defines the gradient of the pavement friction versus speed relationship, is an invariant for any pavement with a given mean profile depth (MPD), regardless of its roughness. This study was conducted to quantify the effect of pavement roughness on the IFI's speed constant. The first phase of this study consisted of theoretical modeling of the LWT using a two-degree of freedom vibration system. The model parameters were calibrated to match the measured natural frequencies of the LWT. The calibrated model was able to predict the normal load variation during actual LWT tests to a reasonable accuracy. Furthermore, by assuming a previously developed skid number (SN) versus normal load relationship, even the friction profile of the LWT during an actual test was predicted reasonably accurately. Because the skid number (SN) versus normal load relationship had been developed previously using rigorous protocol, a new method that is more practical and convenient was prescribed in this work. This study concluded that higher pavement long-wave roughness decreases the value of the SP compared to a pavement with identical MPD but lower roughness. Finally, the magnitude of the loss of friction was found to be governed by the non-linear skid number versus normal load characteristics of a pavement.

Fatal accidents on the road are an unfortunate daily occurrence, with almost 30,000 deaths resulting from hit-and-runs in the USA between 2006 and 2021. The identification of the driver responsible for this road crime can become a challenge. Nonetheless, the accident scene provides a large amount of trace evidence that can prove critical to this matter, one of them being the tire marks. While traditional tire mark analysis is full of physical information helping the reconstruction of the event, additional information can be extracted from the rubber left during the braking event. Each tire model is manufactured with a specific design, obtained by a chemical formulation that can become its signature. Supplemental to the molecular profile of the rubber itself, analysis of the trace and contaminant elements can help build the chemical signature for the tire rubber. This work consists of establishing the link between the tire and the skid mark and particles it left during a braking event. The difference between tire models was proved from the elemental analysis of the tire rubber itself, showing that the specific content of minor and trace elements is specific to the model. Expanding to the problem of tire marks, the first challenge consists in efficiently sampling the rubber from the road. The development of an effective procedure to lift the tire particles from the mark is demonstrated in this work. This does present some challenges, including removal of other particles present within the lift and extraction of the tire rubber for further analysis by ICP-MS, providing an elemental profile for the sampled skid mark. Finally, with the skid mark rubber analyzed, it is compared with the elemental profile of the rubber from the source tire. The results of this comparison will be discussed in both simulated (with a lab- made tire mark maker) and field cases (from braking tests performed by the Florida Highway Patrol (FHP)). The results of my research provide the forensic community with the first evaluation of elemental analysis of tire rubber to use this seldom used trace evidence, all along the analytical process, from sampling to analysis to attribution.