Each winter, Stevens Pass, the North Cascade Highway and all other state highways that pass over the Cascades, get covered with a blanket of snow. When enough snow falls on the North Cascade Highway to create a threat of avalanching and a danger to the public exists, the highway is closed for the season. When the spring highway opening begins, there is normally 10 to 15 feet of flat snow on the roadway and where slides are located there can be 100 to 150 feet of snow or avalanche debris on the road.
Along with the numerous problems the spring highway opening operation incurs, there is also the problem of knowing the exact roadway location. In many spots, this is very critical because of the overall narrowness of the roadway surface and where the roadway makes long sweeping turns. Also, with the large amount of guardrail on Washington Pass, knowing where section of it starts is nearly impossible when buried by deep snow. Another problem met with by maintenance crews during the spring highway opening operations areclogged or buried drains and culverts. Workers spend many hours simply locating them. During the 1991 opening of the highway, much costly damage was done by equipment walking on the top of the snow above buried guardrail and signs. We hope to solve this costly problem by use of the RECCO ]pronounced "wreck-oh"] locator system.
The RECCO Rescue System was developed in 1974, at the Royal College of Technology in Stockholm, Sweden for the ski industry and backcountry skiing enthusiasts. The system is a simple one; individuals wear a small locator on their body and if they need to be found, can be located with a microwave beam bounced off their locator by a small portable receive r/transmitter unit. The idea however, had a "chicken and egg" problem when it came to marketing the product. That is no one wanted to buy the receiver unless there were many locators in use, and no one wanted to buy the locators unless there were receivers available for an emergency. The system has done fairly well in Europe and particularly well in Sweden. Skiers and hikers there are required to purchase the locators before they can journey into the back country.
The receiver is a combination electronic transmitter and receiver containing a sensitive directional scanning antenna, headphones and rechargeable batteries. The scanning antenna is held in the hand and pointed while the combination transmitter and receiver is carried on the back of the operator or inside a vehicle or helicopter. The total unit weighs approximately 14 pounds and transmits a narrow banded microwave signal at a frequency of 915 MHz at about five watts peak power. The receiver section is tuned to 1830 MHz and incorporates a filter which suppresses at 915 MHz.
The locator is a small, thin transponder approximately 5" x 1" x V weighing about half an ounce. It contains a foil aerial and diode that receives a 915 MHz signal from the detector, doubles it to 1830 MHz and returns it to the receiver's antenna. When the receiver detects a signal at 1830 MHz the operator hears an audible response through the unit earphones. Signals rat any other frequency, including those at 915 MHz reflected back from rocks, etc., are not heard.
Since its conception, the RECCO system has gone through several stages of technical updates and evolution. The first system introduced in the late 1980s. Like all new products, did have its problems with reliability and durability. We are working with the third generation of the system and have been informed by the manufacture that problems with the unit are solved. One point to remember is that the system operates with a directional beam and a directional antenna. Because of this system design, you either have a signal or you don't. As a result, the accuracy of the system is remarkable and when a locator is found, it will be located within about four inches horizontally of where the receiver indicates it is
The most obvious use for the RECCO system within the Department is during the spring highway opening operation. To be able to accurately located buried guardrail sections, drains, culvert ends and signs before they are damaged during opening procedures will save money. A large saving will also be realized in not expending many hours trying to locate these items.
The cost of the RECCO system is currently between US$14,000 -15,000 distributed from Canada. The marketing of the system is presently in a severe slump as far as it's used by backcountry travelers. To make the system more well known and widely used, the units can be purchased at a greatly reduced price. The locator tabs are currently priced at about $10.00 a pair (less in quantity). At first glance the price may seem high, but the cost of buying and using the system when compared to the cost of repairing or replacing damaged guardrail sections, signs, and so on, it appears there will be a net saving to the state.
Another value is to maintenance personnel using the system to open the highway. How much value do we place on them knowing exactly where the roadway is located and knowing in fact they are on it and not working on top of snow that can give away?
To test this system, we have done two things. First we have placed 26 RECCO tabs on the North Cascade Highway in key locations; 16 of them on guardrail locations, 4 on historically difficult to locate culverts, and 6 in monuments located in the center of the roadway. The locators placed in the monuments are at roadway location where the avalanche debris has a history of being 100 to 150 feet deep and the location of the road is critical due to the narrowness of the highway.
The second thing we have done is to place 10 tabs on hard to find culvert locations on Stevens Pass. We also placed three tabs in location where we know the snow depth will reach at least 10 to 15 feet. This was done in preparation of a planned demonstration by the RECCO representative.
On March 3,1993 we conducted a test of the RECCO locator system on Washington Pass. Myself, Dale Keep (Maintenance Methods Specialist) and Jerry Holmen (Maintenance Lead Technician) conducted the test. The RECCO unit used was supplied and demonstrated by James Ellis, the North American representative for the RECCO system.
The snowpack was not as deep as we had hoped but the general feeling was that a reliable locator test could be conducted. Also planned was a test of the system working through two different types of materials commonly used by maintenance personnel on the highway. These were a two part epoxy adhesive and cold mix. Tests were conducted with different depths of these materials to determine the reliability of the system with workable amounts of the two materials.
The first test conducted was to see if the system would pick up the tabs placed in the monuments located in the center of the road. Because of the steel cover, we found the system could not reliably locate these tabs. The next test was to see if we could locate the tabs placed on guardrails and culverts. Tests showed both of these applications worked extremely well. The RECCO system was able to locate the tabs very easily through an average snow depth of 5 feet from a distance of about 150 feet. We then buried the tabs I embedded in 1 112 inches of epoxy and cold mix under three feet of snow. The system was able to locate the tab with ease and accuracy. A horizontal distance test showed the system could pick up a reliable signal more than 250 feet away. We were convinced by the test results that the RECCO system could and would work in certain applications.
The RECCO system and its possible applications were discussed at length by those on hand for the test. The general feeling was that there could be some real time and cost saving benefits through the use of the RECCO by Washington State DOT. These could include:
· Road location: The tabs can be embedded in up to 2 inches of epoxy or 12 inches of cold mix at any location on any highway and that location can be found with ease.
· Culvert and Drain locations: Tabs can be placed on any drain or culvert end and can be located under 30 feet of snow.
· Guardrail: Guardrail ends or specific points on a guardrail run can be quickly located under 30 feet of snow.
· Power and Communication lines: Tabs can be located on junction boxes, splices or at specific points along the line and can be found under at least one foot of earth. The activity of the line does not affect the RECCO system. Note; the depth of dirt in which the RECCO can work may be much more. Further test will be needed to determine maximum functional depth for different soil types.
· Avalanche rescue: The tabs will certainly be used in addition to rescue beacons for all maintenance personnel working on the state's mountain passes.
· Equipment: Locating lost radios or oth er expensive pieces of equipment is a proven benefit of the system and has been done many times on the Stevens Pass Ski Area. They have more than once found lost radios using their first generation RECCO system.
The third generation RECCO system currently is not used by anyone in North America. There are a number of the first generation units out there in use. But because o advancements in technology they are far less reliable then the system we tested. The REC CO system is apparently well received and relied on in the European countries. Several rescue operations have the RECCO transmit ter I receiver built into the nose of their helm copters. a lager majority of the ski areas in Europe now own and use the RECCO system Communications with Mr. Ellis have shown him to be very responsive, helpful and informative.
In closing my comments are: As an avalanche control technician working with snow and trying to out guess mother nature for the past 15 years, I have come to trust my gut feeling more and more. My "gut feeling" about this system is that it will indeed save time and money. I know that it would solve the problem on Stevens Pass of locating the fog line on the summit during winter operations. As for Washington Pass, the cost of replacing the Forest Service sign at the summit and repairing the damage to the guardrail two years ago after the spring open ing would have bought two RECCO systems.
Mike Stanford is an Avalanche Technician with the Washington State Department of Transportation, District 2, Berne Snow Camp, Stevens Pass near Leavenworth Washington.