Gravel Roads Research Articles

Various Additives Used as Alternative to Conventional Road Construction

The Western Cape Provincial Administration in South Africa initiated an experimental study to investigate the use of various additives as an alternative to conventional regraveling construction of a gravel road. The in situ material was reworked and stabilized with nontraditional stabilizers. A control section, together with a section stabilized with a traditional stabilizer, was used to compare the performance of the various sections over time. Three sections were also sealed with a bituminous surface and monitored over time. Monitoring of the sections was done either up to the point at which the road surface broke up or for 2½ years. The performance of the different monitoring sections, representing different types of additives and varying-quality (marginal) in situ material—but under the same conditions of climate, traffic volume, and construction technique—were monitored and compared over time. Four main areas of performance were monitored: during construction, in the laboratory, over time, and in economic terms. This paper provides background on the different additives used, a summary of the experimental design, and a brief discussion of the various products. It emphasizes construction and performance monitoring over time and analysis of the results. Apart from interesting observations, conclusions are made by looking not only at performance but also by taking vehicle operating and life-cycle costs into consideration.

Soil Stabilization in Low-Volume Roads

Overwhelming evidence supports the importance of gravel roads. However, road agencies are increasingly faced with the necessity of relying on marginal materials in construction of low-volume roads. Use of these materials necessitates that stabilization be used to alter the engineering parameters to ensure that corrugation, erosion, rutting, poor pass-ability, dust, and low-bearing capacity are avoided. Soil stabilization is increasingly being used as an unsealed-road asset management tool in an attempt to reduce the impacts of these issues, and nontraditional soil stabilizers have been a primary area of focus. Yet few such products have gained widespread acceptance. This paper looks at the lack of usage of alternative stabilizers in the marketplace today from the viewpoint of the product supplier. It aims to identify the issues facing the supplier in introducing a competent nontraditional soil stabilizer product to road agencies and to identify the measures such suppliers can take to advance those products that show good potential. Measures that could be introduced to better manage the field of soil stabilization for unsealed and low-volume sealed roads have been suggested. These measures include the following: established guidelines, specifications, test methods, and management principles, all prepared in a format that is readily acceptable and adopt-able by industry engineers; an industry association; and the adoption of a dedicated research protocol establishing minimum requirements for research on such additives.

Environmentally Sensitive Road Maintenance Practices

The objective of this study was to quantify sediment generation rates from unpaved roads before and after placement of a durable unbound surface aggregate. Sediment pollution from unpaved roads is a well-documented problem across the United States and the world. The quality of road surface material is a large determining factor in how much sediment is generated from the road surface during rain events. This study attempted to quantify the sediment reduction potential of driving surface aggregate (DSA), an unbound aggregate specification used in Pennsylvania that was designed specifically as a wearing course for gravel roads. DSA is widely used to surface roads in Pennsylvania to reduce road runoff in environmentally sensitive areas. The road surface erosion rates in this study were measured on two sites before DSA placement and at time intervals of 1 month, 1 year, and 2 years after placement. A rainfall simulator was employed to generate a consistent and repeatable storm event over a 100-ft (30-m) section of road for this study. Results show that compared with the existing mixed-surface roadway, DSA placement reduced total sediment runoff by 75% after 1 month, 90% after 1 year, and 96% after 2 years for the two sites tested.

Decreasing Moisture Susceptibility of Gravel Road Surface Aggregate by Hydrophobic Treatment Agent

The use of a special hydrophobic treatment agent to reduce the moisture susceptibility of gravel road surface aggregate was studied. A treatment agent and dosage were chosen on the basis of positive results from earlier studies concerning different base course aggregates of paved roads. Laboratory pretesting samples from a chosen test site confirmed that, for example, in tube suction tests the dielectric value of the aggregate treated with the chosen agent and dosage was lowered remarkably as compared with untreated aggregate. This result indicated improved water resistance. The treated aggregate also showed increased abrasion resistance and was less density-susceptible as compared with the untreated aggregate. As a result of the encouraging results from the preliminary tests, a 500-m unpaved test section was constructed in 2009. Ordinary bitumen stabilization machinery was used for simultaneous spreading and mixing of 1% resin-based treatment agent emulsion to the gravel surface aggregate. Although the water content was lower than expected, the construction of the test section succeeded; it will be monitored regularly by falling weight deflectometer measurements and visual inspections.

Financing Low-Volume Road Improvements

Over the past 30 years the population of Washington County, Oregon, has doubled to more than 530,000 residents. With growth limited to the urban area, resources for urban roads mostly kept pace with population growth, but little funding was available for maintenance and improvement of rural local roads. The county has about 250 mi of rural gravel roads in its 1,279-mi inventory. A $50 million investment to pave them all would be challenging to fund and difficult to justify. Creative approaches were needed to fund road improvements. Washington County's Board of Commissioners adopted and backed road maintenance policies, and county voters supported funding initiatives that made possible a variety of creative financing methods to fund low-volume road improvements. This paper discusses how more than 80 low-volume roads that were once gravel were upgraded to a hard surface using financing methods that may be available to other local jurisdictions.

Evaluation of Road Investment Project Effectiveness

Roads in Lithuania are financed only from collected road taxes; however, this funding is not sufficient for road maintenance and improvement. Lithuanian Road Administration under the Ministry of Transport and Communications allocates the funding received from European Regional Development Fund as follows: improvement of pavement of regional roads, implementation of traffic safety and environmental measures, and implementation of Gravel Roads Paving Programme. Since 2004 road projects in Lithuania have been financed from European Union funds. Unfortunately these financial resources are not sufficient for the implementation of all road investment projects in Lithuania. The problem of selecting the most effective road investment projects is becoming more and more acute. Road investment project alternatives have to be appraised in an integrated manner using mathematical models in addition to economic, social and environmental criteria. Scientific problem – road investment projects are often appraised from economic, social and environmental viewpoints separately by applying different mathematical models and without using the principle of sustainable development and multi-criteria appraisal methods for integrated analysis of road investments. The authors propose to select criteria from sustainable environment components, which best reflect economic, social and environmental aspects. It should be noted that these economic, social and environmental aspects are interrelated and complementary, and therefore influence the appraisal of road investment projects. The article analyses and evaluates the effectiveness of road investment project alternatives by combining economic, social and environmental aspects and processing the data using expert and multi-criteria appraisal methods. Scientific novelty – an integrated evaluation of economic, social and environmental aspects by using multi-criteria appraisal methods is proposed. The aim of the research – to present the road investment project appraisal methodology based on the principle of sustainable development and perform the appraisal of the alternative projects by making computations according to expert and TOPSIS (Technique for the Order Preference by Similarity to Ideal Solution) appraisal methods. The object of the research – road investment projects. The methods of the research – expert and multicriteria appraisal method TOPSIS is applied.

Distribution and risk factors for spread of amphibian chytrid fungus Batrachochytrium dendrobatidis in the Tasmanian Wilderness World Heritage Area, Australia

Chytridiomycosis is an emerging infectious disease caused by the pathogen Batrachochytrium dendrobatidis (Bd) and is the cause of the decline and extinction of amphibian species throughout the world. We surveyed the distribution of Bd within and around the Tasmanian Wilderness World Heritage Area (TWWHA), a 1.38 million ha area of significant fauna conservation value, which provides the majority of habitat for Tasmania's 3 endemic frog species (Litoria burrowsae, Bryobatrachus nimbus and Crinia tasmaniensis). Bd was detected at only 1 (3%) of the 33 sites surveyed within the TWWHA and at 15 (52%) of the 29 sites surveyed surrounding the TWWHA. The relatively low incidence of the disease within the TWWHA suggests that the majority of the TWWHA is currently free of the pathogen despite the fact that the region provides what appears to be optimal conditions for the persistence of Bd. For all survey sites within and around the TWWHA, the presence of Bd was strongly associated with the presence of gravel roads, forest and < 1000 m altitude--factors that in this study were associated with human-disturbed landscapes around the TWWHA. Conversely, the presence of walking tracks was strongly associated with the absence of Bd, suggesting an association of absence with relatively remote locations. The wide distribution of Bd in areas of Tasmania with high levels of human disturbance and its very limited occurrence in remote wilderness areas suggests that anthropogenic activities may facilitate the dissemination of the pathogen on a landscape scale in Tasmania. Because the majority of the TWWHA is not readily accessible and appears to be largely free of Bd, and because Tasmanian frogs reproduce in ponds rather than streams, it may be feasible to control the spread of the disease in the TWWHA.

Possibilities for the Improvement of the Quality of Design Solutions in the Gravel Road Reconstruction Projects

This article provides a summary of the author’s PhD thesis on possibilities for the improvement of the quality of design solutions in gravel road reconstruction projects. The thesis includes five chapters: analysis of the Gravel Road Network in Lithuania and analysis of the gravel roads development; analysis of the road design standards of the Republic of Lithuania compared to other countries; methodology of experimental investigations; results of the investigations; and conclusions based on the investigation results. In this work, the author proposes a new road design methodology in which road alignment is characterized as a sequence of successive interrelated elements, including traffic safety criteria. The author concludes that present regulations for road design in the Republic of Lithuania are inaccurate and deficient and should not be used for road reconstruction projects, particularly on gravel roads. Recommended corrections and supplements to these regulations are presented. The original thesis, in Lithuanian, is available upon request from the author.

Research on Motor Transport Produced Noise on Gravel and Asphalt Roads

Vehicles in motion on roads are the main source of noise in the environment. The noise in a car is created by structural noises from car construction, originated from vibrations in an engine, cabin, silencer, wheels and tires. Traffic noise flow depends on its intensity, motion speed, flow composition and extent, quality of the road pavement and build-up of the area along the road. This paper contains research on motor transport-produced noise levels on roads of regional significance with gravel and asphalt pavement in Moletai district. The level of motor transport-produced noise was measured in wintertime and summertime at the chosen typical locations considering the nature of the asphalt and gravel road pavement and different landscape morphology forests, topography roughness, open area, upslope, downslope, etc. Also, research of noise level dependence on car speed was performed from 50 km/h to 70 km/h. It was determined during the study that noise level produced by a car moving at a speed of 50 km/h on a road with gravel pavement is higher by 4 dBA than that on a road with asphalt pavement. Upon moving away from the noise source by 50 m, the level of noise decreases by 12 dBA in woodland open areas and by 16 dBA. As car speed increases from 40 km/h to 50 km/h in wintertime, the level of noise rises by 2 dBA. In summertime, as car speed increases from 50 km/h to 70 km/h, the noise level rises by 5 dBA. These differences are due to the presence of ice and snow on the road in winter. Noise depends on physical properties of tires, type of pavement, car vibrations and in particular on pavement roughness.

The Built Environment and the Architecture of a Performance: Arcosanti, Chicago, and the Making of Theoretical Isolation: A Post-Atomic Experiment

The Built Environment and the Architecture of a Performance:Arcosanti, Chicago, and the Making of Theoretical Isolation: A Post-Atomic Experiment Chloe Johnston (bio) and Ira S. Murfin (bio) "Imagine, if you will, a kind of . . . shipwreckA big weather patternColliding with another weather patternAlso there's a wooden structure thrown in there for good measureWhat do you get?You get a disaster.Get it? We're colliding stories and it's going to be disastrous.See?" —Theoretical Isolation: A Post-Atomic Experiment "The Urban Effect is that fundamental phenomenon in which two or more particles of physical matter begin to interact in ways other than statistical and fatal. That is to say, in ways which are organic or living, and eventually the instinctive, self-conscious, mental, cultural, and spiritual ways. It is this Urban Effect around which the whole of life is clustering itself." —Paolo Soleri1 Introduction The arrival at Arcosanti—an experimental architectural project in the high desert of Arizona—is a long one. You turn off Interstate 17, travel on a gravel road for two-and-a-half miles, your tires kick up dust all the way, and if you pass another car, you wave, because you have this space in common. The drive down the road gives you time to think about this. You try to catch a glimpse of the place itself. It bobs in the distance as your car goes over hills, like a boat approaching the shore through choppy waters. When you finally pass the rusted sign, you might get excited, because you think you know something about where you are, or because you know nothing, and you are the kind of person who likes that (Fig. 1). In March 2009, the Laboratory for the Development of Substitute Materials (LDSM) marooned itself for ten days on a mesa in Arizona.2 We had, for the previous several months, been preparing a template for a structured response to that environment upon arrival. The collaboratively devised performance produced from this experiment, Theoretical Isolation: A Post-Atomic Experiment, integrated Shakespeare's The Tempest; research on the development of the atomic bomb by the Manhattan Project at Los Alamos, New Mexico; and the work of Italian architect Paolo Soleri, the founder of Arcosanti.3 We had deliberately marooned ourselves there and, like the shipwrecked Neapolitan nobility in The Tempest or the physicists arriving by train in New Mexico to work on the [End Page 133] Manhattan Project, we sought to create a process that would address this question: Why do certain individuals recede from civilization in order to re-imagine it? Click for larger view View full resolution Fig. 1. Arcosanti, Arizona. (Photo: Chris Ohlinger, reprinted by permission of the Cosanti Foundation.) The project was inspired by a historical anecdote. In The Making of the Atomic Bomb, Richard Rhodes recounts an event at a cocktail party at Los Alamos: "(Edward) Condon pulled from a bookshelf a copy of Shakespeare's The Tempest and skimmed it for speeches meant for Prospero's enchanted island that might play contrapuntally against Oppenheimer's high and dry and secret mesa" (468). By exploring this connection at Arcosanti, the project unfolded against a landscape similar to the desert mesa where the first atomic bomb was built. In this article, we analyze the process of creating Theoretical Isolation: A Post-Atomic Experiment as a performance that is architecturally determined in both form and content in order to expand the practical understanding of site-specificity to include theoretical context and to argue for architecture as a collaborative presence in devised work. We took both the physical architecture and the ideological content of the site—a prototype for arcology, Paolo Soleri's urban-design concept for compact and environmentally friendly cities—as collaborator in structuring the content with which we arrived. Once written onto one specific site, Arcosanti, the performance was re-imagined and grafted onto an entirely different performance space, The Neo-Futurists' theatre, The Neo-Futurarium, in Chicago. At Arcosanti, we worked within the unusual structure of this architectural experiment, creating a promenade performance that moved the audience around the small community, culminating in an outdoor amphitheatre where we...

Multi-channel ground-penetrating radar to explore spatial variations in thaw depth and moisture content in the active layer of a permafrost site

Abstract. Multi-channel ground-penetrating radar (GPR) was applied at a permafrost site on the Tibetan Plateau to investigate the influence of surface properties and soil texture on the late-summer thaw depth and average soil moisture content of the active layer. Measurements were conducted on an approximately 85 × 60 m2 sized area with surface and soil textural properties that ranged from medium to coarse textured bare soil to finer textured, sparsely vegetated areas covered with fine, wind blown sand, and it included the bed of a gravel road. The survey allowed a clear differentiation of the various units. It showed (i) a shallow thaw depth and low average soil moisture content below the sand-covered, vegetated area, (ii) an intermediate thaw depth and high average soil moisture content along the gravel road, and (iii) an intermediate to deep thaw depth and low to intermediate average soil moisture content in the bare soil terrain. From our measurements, we found hypotheses for the permafrost processes at this site leading to the observed late-summer thaw depth and soil moisture conditions. The study clearly indicates the complicated interactions between surface and subsurface state variables and processes in this environment. Multi-channel GPR is an operational technology to efficiently study such a system at scales varying from a few meters to a few kilometers.

Study on Road Simulation Test of Motorcycle

The principle of remote parameter control(RPC) and test method of road simulator test are analyzed, and the road simulation test of motorcycle is implemented with road simulator produced by MTS company. Firstly, by disposing strain gauge and accelerometer, the load spectrum of motorcycle is sampled when the motorcycle runs on gravel road and concrete road with constant speed. Then using the front and rear axle acceleration as desired response signals, the simulation iteration and road simulation test are conducted. At last, the key problems of motorcycle road simulation test are solved. The result shows that the desired response signals and the monitor signals are well matched, and the road load spectrum of motorcyle is accurately reproduced.

Attitudes towards current and lowered speed limits in Australia

The present study was concerned with gaining a greater understanding of the Australian community's attitudes towards both the current and proposed lower speed limits. An online survey was administered in four states (Victoria, South Australia, Western Australia, and Tasmania), with a total of 4100 respondents recruited. The survey focussed on attitudes towards speed limits for four different road types, and the sample was stratified according to age, gender, and area of residence. It was found that most respondents were able to correctly identify the speed limit for local residential streets and major urban arterials, although their knowledge of rural speed limits was considerably lower. The majority of respondents were in favour of the proposed lower speed limits on 100 km/h two-lane undivided rural roads and on rural gravel roads, but only about one-third supported lower limits in urban areas. A cluster analysis revealed that there were varying characteristics between respondents who were more or less likely to support speed limit reductions, across a number of demographic, socio-economic status, and driving behavior variables. These results provided important guidance regarding groups that could potentially be targeted in speed-related interventions, as well as highlighting the potential for lowering speed limits in Australia, particularly on rural roads.

Evaluation of Criteria for Setting Speed Limits on Gravel Roads

Even though speed limits of gravel roads are typically set based on statutory guidelines, there are some instances where exceptions are allowed and in place. In the absence of detailed literature on the subject, this study made an effort to evaluate and compare two criteria used in setting speed limits on low-volume gravel roads, with the intention of providing guidelines for future use. Field speed data were collected at a number of straight, level sections of gravel roads in Kansas where there is sufficient sight distance. Several sites located in two adjoining counties that use two different criteria for setting speed limits were also specifically selected for comparison purposes. One of the two counties adopts 35-mph speed limits on gravel roads and posts speed limit signs similar to those on paved roads. Characteristics of gravel roads in the adjoining county are very similar except that the speed limit is governed by the statutory limit (55 mph) and not posted. Collected actual speed data indicated no significant differences between the two speed data sets. In addition to operational speed comparisons, crash experience was also taken into consideration, which showed no major differences in terms of safety. When looking at the findings of this study, it is clear that lowered, posted speed limit values on gravel roads have not necessarily helped in improving either operational conditions or safety. Rather, reduced posted speed limits on gravel roads have increased the percentage of speed limit violators. Accordingly, care should be taken in making such decisions in the future for new situations.

The Impact of Upgrading Roads on the Conservation of the Threatened Flightless Dung Beetle,Circellum bacchus(F.) (Coleoptera: Scarabaeidae)

The flightless dung beetle Circellum bacchus (Fabricius, 1781) is a unique, ectothermic dung beetle that is of conservation concern due to a massive decline in its distribution. Very little is known about its conservation ecology and the upgrade of roads in one of its last strongholds, South Africa's Addo Elephant National Park, led to concerns that road kill was threatening the population because drivers could not see the beetles due to their similar colour as the upgraded roads. We tested whether the upgraded, black, tar roads led to more road kills than the original sandy-red, gravel roads using counts of live and dead beetles along transects through similar habitats of the park. There was no significant difference between the number of live and dead dung beetles on the tar or gravel roads illustrating that the infrastructure improvements themselves are not threatening the persistence of the species. The high levels of vehicle-derived mortality along roads, however, suggest that road kills may be a threatening process with potentially 100,000 C. bacchus killed on roads annually (although 45,000 is a more conservative estimate). Further research is needed to ascertain whether this off-take is sustainable and to formulate mitigation measures.

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.

Murder by Duel: Welch, West Virginia, 2009

Murder by Duel: Welch, West Virginia, 2009 Bertram Wyatt-Brown (bio) Historians are sometimes called to the witness box in civil trials, chiefly regarding questions of racial discrimination, historic preservation, broken Indian treaties, and civil rights cases. Seldom, however, does a member of our profession serve as an expert witness in a criminal trial. I, however, did just this in the case of State v. Simpson in January 2009. I may be the only historian ever to take that role in a murder case.1 Serving as a witness leads the historian to unexpected and perhaps troubling discoveries. In this case, the distance between the cloistered world of letters and the culture of an Appalachian region cannot be measured in miles alone. Welch, West Virginia, the seat of McDowell County, was once a thriving coal-mining center. The town sits in a steep ravine. Wood-frame houses perch precariously on either side. It is a rough, hardscrabble part of the country, far from the life that many of us in the academic line would ever know. When my wife Anne and I checked out of the comfortable Count Giuli Motel, Jack, the manager, apprised us of local history. The Hatfields and McCoys, he reminded us, had battled each other in the 1880s across the nearby Kentucky border. During the 1920–21 coal strike Constable Sid Hatfield had been killed. Detectives hired by coal mine operators blamed the Matewan policeman for the deaths of some of their colleagues and sought revenge. They shot Hatfield just across the street from a second courthouse where the State v. Simpson trial was located. A film, Matewan, tells the story. In its prime McDowell County boasted 100,000 residents, now reduced to 5,000. The coal seams gradually played out. In late April 2008 an e-mail from Lacy Wright, Jr.’s law office in Welch asked me to assist the defense of his client, Steve Simpson. I readily accepted. Soon afterward, a packet of court documents arrived. They included the arresting officer’s report, the witnesses’ statements, and photographs of the crime scene. The circumstances were these. Standing near a gravel road in Gilliam Bottom, not far from Welch, at about 4:30 in the afternoon on April 20, 2008, Stephen Bryant Simpson, 49, shouted in fury and indignation at a passing ATV. Dana Martin, 41, was speeding at about 50 mph in a 15 mph zone. Children were playing along the roadside. Moreover, Martin’s vehicle was also spraying Simpson’s parent’s car with showers of paint-scarring stones. Warning him to stop for the sake of the kids, Simpson got in his truck and tried to immobilize Martin’s four-wheeler against a chain fence. Martin leapt angrily from his vehicle. He struck Simpson with his volunteer fire department cell phone. Simpson, who has a game leg, staggered off. But Martin pinned him against a fence. He grabbed Simpson’s crutch and tried to beat him with it. The fracas drew other onlookers to the unfolding drama. At some point, the pair broke apart. As Martin prepared to leave for home, he shouted that he would be back, and “I ain’t gonna be empty-handed.” Simpson went up the road to retrieve a Rossi revolver with .357 bullets in the chamber. He then headed back to Gilliam Bottom. As promised, Martin soon materialized, armed with a Sig Arms Mauser semi-automatic .45 caliber weapon. Almost immediately he fired into Simpson’s pickup. He blew out the windshield and back window. Bullets caromed around the inside of the cab. Robert Green, Simpson’s coworker, was in the vehicle next to Simpson. Both jumped out unharmed. As Martin advanced, Simpson fired back but without success. Then, gaining a better view, he struck Martin in the left chest. The impact spun him around. A second shot entered Martin’s lower back. He fell across the hood of Simpson’s pickup and slid to the ground. Despite some witnesses’ attempts of CPR, he was dead before an ambulance appeared. Ordinarily, in such cases of “mutual combat,” or “affray” to adopt legal terms, the survivor is subject to indictment for second-degree murder or, given...

Effect of Components Content on Properties of Hot Mix Asphalt Mixture and Concrete

The article contains general characteristics of Lithuanian motor roads and possibilities of their development. 63.72% of Lithuanian motor roads of national importance (according to their length) have asphalt pavement. It is shown that modernization of national motor roads mainly includes paving of gravel roads. It is pointed out that the main indices characterizing the condition and service life of asphalt pavement and its construction are: hot mix asphalt (HMA) concrete resistance to binding tension, tensile elasticity modulus and fatigue resistance. The values of these indices highly depend on the componential composition and structure of HMA concrete as well as on the degree of its compaction. The suitability of HMA concrete for road pavement construction is well characterized by its physical mechanical indices according to Marshall: stability S, flow F, volume of air voids Va etc. These indices also are highly dependent on the composition and structure of HMA concrete. Investigations carried out in the Lithuanian motor roads and in laboratory helped to determine asphalt concrete dependencies between the componential composition of HMA concrete and values of its physical and mechanical properties according to Marshall. Conclusions and recommendations are included.

Dynamic Responses of Calving Caribou to Oilfields in Northern Alaska

Past research has suggested that during the calving period, caribou (Rangifer tarandus) in Arctic Alaska generally avoid areas within 1 km of oilfield roads with traffic. However, avoidance is not absolute, and caribou may habituate to infrastructure (e.g., buildings, roads, well pads) and human activity. We conducted road-based surveys of caribou in oilfields on Alaska’s Arctic Coastal Plain during the late calving and post-calving periods of June in 2000–02. We recorded location, composition, and behavior of caribou groups located less than 1 km from active gravel roads and production pads. Caribou groups with calves were on average distributed farther from oilfield infrastructure than were groups without calves, but habituation to oilfield activities, indicated by decreased avoidance, occurred at similar rates for groups with and without calves. During the calving period, sighting rates were greater in areas of low human activity, and calf percentages tended to be greater at night when oilfield activity was reduced. Caribou groups were on average closer to infrastructure during the post-calving periods than during the calving periods in 2000 and 2001, but not in 2002. In 2002, when snow melted early, caribou groups were closer to infrastructure during the calving period than in 2000 and 2001, when snow melted later, emphasizing the importance of examining environmental variables when investigating the dynamic interactions of caribou and oilfields. Overall, caribou appeared to habituate to active oilfield infrastructure after the calving period in 2000, late in the calving period in 2001, and likely before our sampling period in 2002. The timing of annual rehabituation was positively correlated with timing of spring snowmelt. Land and wildlife managers can use information from this study to develop calving period-specific mitigation measures that are more effective and flexible.

Factors Affecting Crash Severity on Gravel Roads

This study focused on the characteristics of crashes reported on gravel roads, with the objective of identifying factors affecting severity of crashes on such roads. Crash data from Kansas over a 10 year period was used in the analysis. Logistic regression models were developed to estimate the probability of having a crash of different level of severity for a given set of explanatory variables. The regression modeling considered 29 candidate variables related to driver, road, environment, and collision type, which have been recorded by the police. It was found that multiple factors were very significant in these models, such as safety equipment usage, driver ejection, alcohol involvement, speed limit, and some driver-related factors. Existence of these factors was very likely to result in high-severity crashes on gravel roads, compared to the circumstances without them. The magnitude of such contributing effects was also estimated by computing the conditional odds ratios for individual predictors.