References on road salt issues
There are three broad policy issues surrounding winter maintenance activities to preserve safety and mobility on our roadways:
Roadway Performance -- how well is our roadway system delivering passengers and goods to their intended destinations in a safe and reliable manner. Thus, roadway operations compete for attention and resources with those who build and maintain the physical infrastructure. Effective delivery of snowfighting services builds on the performance measurement metric, so advocacy of improved snowfighter professionalism is lumped into this category for our purposes here.
Roadway safety -- how well integrated are the functions of winter maintenance and roadway safety. Too often "safety" has meant special programs to educate drivers (or place standards for vehicle construction) while overlooking the major roadway safety role of winter snowfighting operations as well as the safety features engineered into the physical roadway infrastructure. State highway safety plans should integrate operations into the safety program recognizing their critical safety role and educating the public on this benefit of their taxpayer investment.
Environmental protection -- all deicers have environmental impacts on the natural and man-made environment. Roadways can be engineered to reduce or eliminate much of the threat, but operations must employ best practices, like Sensible Salting, to fully realize our stewardship for our environment.
Resources bearing on these issues are organized under these topics, though the issues sometimes overlap:
The Federal Highway Administration's Office of Operations has a program on road weather management which has played a vital role in moving forward with the technology development and implementation and policy support for improved snowfighting.
National Transportation Operations Coalition (NTOC). NTOC has a membership of a couple dozen organizations representing elected officials, transportation agencies and private transportation sector associations (like the Salt Institute). It is an important resource in promoting practical metrics to assess the operating performance of the U.S. roadway system.
TRB Committee on Winter Maintenance . TRB sets the research agenda in cooperation with AASHTO (see below). TRB sponsors a quadrennial Snow and Ice Symposium where valuable resource materials address developing issues.
TRB Committee on Performance Measurement . This committee is guiding development of the technologies and systems required to provide real-time and strategic assessment information to enable improved roadway performance.
American Association of State Highway and Transportation Officials (AASHTO) Maintenance subcommittee . AASHTO is composed of state transportation agencies and has a vital, pro-active role in advancing the snowfighting profession, particularly through its SICOP (Snow and Ice Cooperative Program ). Leaders of AASHTO's Winter Maintenance Technical Services Program represent the inner circle of public sector leaders in snowfighting. SICOP operates (actually, the host is the University of Iowa) an invaluable Snow-Ice Listserv. AASHTO has published a valuable Winter Maintenance Guide (especially see Chapter 8 ). AASHTO/SICOP have developed valuable computer-based training materials; see our Education Center .
Clear Roads . This is an important pooled-fund winter maintenance research organization.
Dwayne Collett hosts a useful Winter Maintenance Podcast program. Be sure to browse the archive.
Transportation Association of Canada (TAC). TAC represents provincial and local transportation agencies in Canada. It has produced valuable Road Salt Syntheses of Practice which are integrated closely with a national Road Salt Code of Practice. Snowfighting professionals should check out its training offerings in our Education Center .
Snow & Ice Management Association (SIMA). SIMA represents private snowfighting contractors.
American Highway Users Alliance (AHUA). AHUA represents customers of snowfighting services and performs a vital service in articulating and popularizing developing themes of improving highway operations. Another important customer group is the American Trucking Associations (ATA). And yet another vitally concerned association is the International Bridge, Tunnel and Turnpike Association (IBTTA).
Pacific Northwest Snowfighters (PNS). PNS represents several states and provinces in Pacific Northwest. It is primarily concerned with corrosion impacts of various deicing chemicals (but is included here for ease of reference).
National Association of County Engineers (NACE). NACE, as its name indicates, represents county engineers; they are responsible for snowfighting on largely rural, often-unpaved two-lane roadways.
Many of the preceeding groups take an active interest in roadway safety. In addition, these groups contribute to the policy discussion:
Roadway Safety Foundation (RSF). RSF takes a customer view of the importance of a safe roadway operating environment.
National Safety Council (NSC). NSC is primarily interested in safe drivers, but occasionally considers safe roadway infrastructure.
Canada Safety Council (CSC). CSC recognizes roadway conditions as the prime threat to winter driving.
Governors Highway Safety Association (GHSA). GHSA is the target for advocacy of integrating safety programs and winter operations.
In addition, these documents will be of value:
Kuemmel and Hanbali. Accident Analysis of Ice Control Operations (The Marquette Report, 1992).
Knapp and Kroeger, Mobility and safety impacs of winter storm events in a freeway environment (2000)
Salt is the primary roadway deicer and because of the quantity required to maintain safe and passable roads, it can contribute chlorides to the environment in concentrations which are problematic to flora, fauna, roads, bridges and vehicles. Some agencies mix salt with sand; the sand has its own significant environmental problems. And other deicers are also used in conjunction with salt or as an alternative. Every deicing chemical has its own environmental challenges; some are masked because the chemical is used in such limited quantities that it does not reach the threshold of concern. Some studies compare and contrast materials, but salt is -- by far -- the most studied material. These resources include review studies of original investigations. With regard to salt, the primary concerns are chloride levels that may create taste problems in drinking water or reach concentrations of concern to the health of plants and animals (but not humans) and contributing to the corrosivity threat to roadways, bridges and other roadway-related infrastructure. These are the key documents to start any review of the environmental impacts of salt.
TRB Special Report #235, Highway Deicing: Comparing Salt and Calcium Magnesium Acetate (1991). Individual chapters are devoted to examining salt's effects on motor vehicles and infrastructure, the environment, and drinking water. National costs are estimated for some effects. After reviewing the evidence, the committee concluded that the widespread use of CMA as a general replacement for salt is unlikely and unwarranted.
Environment Canada's Road Salts Assessment Report (2001). A more politically-motivated document than the TRB report was prepared by Environment Canada. The report is a useful overview though the conclusions are routinely overstated.
Use of abrasives in winter maintenance at the county level
by Wilfrid Nixon (2001). This paper reviews studies which suggest that at highway speeds sand is swept off the road by relatively few vehicle passes (8 to 12) and that friction gains from sanding (when the sand remains on the road) are minimal. There are increasing environmental concerns about sanding. Some U.S. cities have already stopped sanding because of air quality concerns. Others are required to clean up all sand as soon as possible after application, using street sweepers.
NCHRP Report 577 tool for selecting a deicer . This small computer program developed for the National Cooperative Highway Research Program (NCHRP) in its Report 577 to enable agencies to incorporate environmental factors into their selection criteria for salt and alternative deicers.
With regard to vehicular corrosion, SAE International is the place to start. See U. S. Automotive Corrosion Trends: 1998 SAE (Acap) Automotive Body Corrosion Survey Results by Butch Tiburcio (2003).