Rand Decker

Application of capacitance instrumentation to the measurement of density and velocity of flowing snow

Abstract We describe capacitance instrumentation suitable for the measurement of density and velocity of flowing snow with moderate liquid-phase water content. A wand, consisting of two adjacent sensors protected by guard circuits, produces signals that are related to snow density through calibration. Cross-correlation of the signals permits velocity measurements. Calibration is accomplished using a capacitance device that records the dielectric properties of a snow sample while subjecting it to controlled levels of compaction and volume change. Non-invasive probe geometries are also presented. The instrumentation is tested in artificial and natural avalanches.

MEASURING EFFICIENCY OF WINTER MAINTENANCE PRACTICES

The need to objectively evaluate the effect of new technology and the advent of externally contracted winter maintenance have increased the need for quantitative measures of winter maintenance efficiency and effectiveness. Varying severity of winter storms and lane kilometers within a maintenance facility’s service area together largely account for storm-to-storm differences in the cost of fighting snow. Efforts were made to develop a measure of winter maintenance efficiency that accounts for labor, equipment, and material costs, as well as storm severity and duration, for an established number of lane kilometers of given service levels. The expenditures are normalized by the lane kilometers in the maintenance facility’s service area and a storm severity index. The storm severity index (WI) is a modified winter index calculated from weighted daily snowfall totals and minimum and maximum temperatures. The resulting winter maintenance metric (daily snow-fighting

Avalanche hazard reduction for transportation corridors using real-time detection and alarms

/WI × lane-km) is a normalized measure of a maintenance facility’s efficiency in performing snow- and ice-control operations. Databases and resulting winter maintenance efficiency metrics were developed for the winters 1996–1997, 1997–1998, and 1999–2000 for three Utah Department of Transportation maintenance facilities. The efficiency of these three sheds is compared for the winter of 1996–1997, and the winter maintenance efficiency is considered at one shed for specific storms during winter 1998–1999. The winter maintenance efficiency metric allows maintenance managers to objectively consider storm-to-storm efficiency within a facility and to compare the storm-to-storm and annual efficiency of facilities. The impact of new technology on winter maintenance and the efficiency with which contract organizations perform snow-fighting duties can be measured with a winter maintenance metric.

Evaluation of a fixed anti-icing spray system

Increased travel demand for safe, reliable winter travel on the alpine roads of the Western USA has resulted in an increased hazard to motorists and highway maintenance personnel from snow avalanches. Presented here are configurations for systems that can detect and provide, in real time, warnings to motorists and highway maintainers of the onset of avalanching onto the roadway. These warnings include: on-site traffic control signing and in-vehicle audio alarms for winter maintenance vehicles, as well as notification capability to maintenance facilities and/or centralized agency dispatchers. These avalanche detection and warning systems are capable of detecting an avalanche-in-progress and use the remaining Time of Descent of the avalanche to initiate the on-site alarms. Alternatively, real-time knowledge and notification of the onset of avalanching may be used to proactively manage the evolving hazard over an affected length or corridor of highway. These corridors can be several tens of kilometers in length and may, otherwise, be very remote, low volume rural highways. As a consequence, these systems must be cost-effective alternatives to presently available avalanche hazard reduction technology used on highways. Results and experiences from deployed systems in Idaho and Wyoming from the winters of 1997/98, 1998/99, and 1999/2000 are presented here.

Rural Intelligent Transportation System for Snow Avalanche Detection and Warning

Each year hundreds of automobile drivers have accidents caused by iced-over bridges adjacent to roads that are free from ice. Ice forms on bridges because the ground does not insulate them; therefore, the temperature of a bridge deck rapidly cools to the ambient air temperature, which is often well below freezing. This is particularly evident on the Interstate 215 overpass/exchange at 6200 South Street in Salt Lake City, Utah. This bridge averages more than 24 accidents per winter season because of snow and ice conditions. A system was installed at this location that applied the anti-icing liquid agent magnesium chloride (MgCl2) to the northbound lanes of the freeway bridge deck. The southbound lanes received no additional treatment, other than the efforts of the Utah Department of Transportation’s snow- and ice-removal operators. The anti-icing spray system is parapet-mounted and delivers approximately 360 L/lane-km/spray (95 gal/lane-km/ spray) event of MgCl2. The effectiveness of the spray system was analyzed for the 1997 and 1998 winter season. The system reduced the number of accidents caused by snow and ice on the northbound side of the road by 64 percent. The ratio of the number of accidents occurring on the treated northbound side of the road to the number of accidents occurring on the untreated southbound side was reduced from 1.4 to 0.7. The anti-icing system proved effective in reducing the number of accidents that occur on this very dangerous section of roadway in Utah.

RURAL INTELLIGENT TRANSPORTATION SYSTEM NATURAL-HAZARD MANAGEMENT ON LOW-VOLUME ROADS

The growth of winter travel on alpine roads in the western United States, a result of the demand for reliable winter access, has increased the hazard to motorists and highway maintenance personnel from snow avalanches. Configurations are presented for systems that can detect and provide, in real time, warnings to motorists and highway maintainers of roadway avalanches. These warnings include on-site traffic control signing, in-vehicle audio alarms for winter maintenance vehicles, and notifying maintenance facilities or centralized agency dispatchers. These avalanche detection and warning systems can detect an existing avalanche and use the avalanche’s remaining time of descent to initiate on-site alarms. Alternatively, real-time knowledge and notification of the onset of avalanching may be used to proactively manage the evolving hazard over an affected length or corridor of highway. These corridors can be several tens of kilometers in length and may be very remote, low-volume rural highways. As a consequence, these detection and warning systems must be cost-effective alternatives to existing avalanche hazard reduction technology. Results and experiences from the winters of 1997–1998 and 1998–1999 are presented, along with recommendations and criteria for future deployment of these automated natural hazard reduction systems for rural transportation corridors.

Prospects for Numerical Analysis of Interaction between Fluid Flow and Structural Vibration

The growth of winter travel on alpine roads in the western United States has increased the risk to motorists and highway maintenance personnel owing to a variety of natural hazards. Hazards include snow and ice, avalanching snow, and blowing and drifting snow. The conditions call for attendant need for incident response. A substantial number of affected routes are low-volume rural winter roads. Configurations have been developed for rural intelligent transportation system (ITS) technology that can detect hazards and provide, autonomously and in real time, warnings to and traffic control actions for motorists, highway maintainers, and incident responders for roadway natural hazards. These warnings include on-site traffic control signing and road closure gates, in-vehicle audio alarms for agency maintenance and patrol vehicles, and notification to highway agency maintenance facilities or centralized multiagency dispatchers. These actions and notifications are initiated automatically from the remote rural sites and via manual intervention from off-site personnel, well removed from the rural roadway corridor itself. About 5 years of experience have been accumulated in using these rural ITS natural-hazard reduction systems, including snow avalanche detection and warning systems on Loveland Pass, Colorado; Hoback Canyon, Wyoming; and Banner Summit, Idaho. Automated road closure gates on the Teton Pass in Idaho and Wyoming now allow for remote road closure during heavy snow events. These cost-effective ITS natural-hazard systems are highly exportable for other processes that affect rural low-volume roadways, including landslide, flooding, high surf, high winds, loss of visibility, wildlife, and other natural hazards of this type.

Modal analysis of segmented, laminated, anisotropic, inhomogeneous beams

Publisher Summary Prospects for numerical analysis of interaction between fluid flow and structural vibration research needs in the emerging field of computational wind engineering (CWE) are driven in large part by the wind engineering requirements of the structural engineering community. This includes efforts to accurately simulate, aerodynamically tailor and/or control the structural motions that result from the wind. The prospect of practically applying the results of numerical simulations of fluid flows about bluff body analogues of flexible, vibrating civil structures was examined and discussed during in a workshop held specifically for this purpose during the CWE92, Symposium, University of Tokyo, August, 1992. Progresses of CWE were demonstrated by individual workshop participants who summarized their views on the future prospect. Three themes or key issues came to the forefront during panel discussions after workshop presentations: (1) CWE as a possible tool in structural design practice, (2) accuracy and reliability of the numerical solutions, and (3) the role of experiment and wind tunnel testing in CWE.

Computer applications for avalanche forecasting in the United States

Early skis were made from wood, they varied in length, width and thickness but all were similar in performance. They now have very different performance characteristics from the giant slalom, racing, bump and recreational skis. However, very little is known about the changes in these materials after thousands of cycles of finite strain levels. We study the dynamic behavior of skis using the nondestructive technique of modal analysis. This method separates the fundamental modes of vibration. The mode shapes are generated and the dampening factors are calculated for the different modes. Each mode is dynamically displayed on a computer and the data sets printed out. The goal is to determine why and how skis change their dynamic response.

Service learning as a strategy for engineering education for the 21st century

Avalanche hazard forecasters must evaluate a number of different important parameters which often vary markedly over time and distance. Computer applications have been developed to help the avalanche forecaster manage the complex data. These include programs which simply graph and tabulate data into easily ingested displays, database and statistical software, deterministic models of the snowpack evolution and stability, and finally, networks of avalanche information. This paper is an overview of computer software currently available in English and in use in the United States.