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TRANSPORTATION RESEARCH DIGEST

ARIZONA TRANSPORTATION INSTITUTE

e-mail jsemmens@cox.net

APRIL 2004

Snow and Ice Control: Guidelines for Materials and Methods, NCHRP Report 526 by Robert R. Blackburn, Karin M. Bauer, S. Edward Boselly & A. Dean Mcelroy (Transportation Research Board, 2101 Constitution Avenue, N.W., Washington, D.C. 20418; ph. 202-334-2934; http://www.national-academies.org/trb/bookstore) (2004)

Highlights

snow and ice control treatment should be individually designed to produce an effect that is consistent with the LOS goals

most agencies provide treatment until "bare" pavement is achieved

The goal of effective snow and ice control programs should be to provide the highest level of service (LOS) possible within the constraints of available resources and environmental responsibility. LOS goals are viewed from the time frames of within-winter weather event and after-end-of-winter weather event. After-event LOS is sometimes a moving target due to blowing and drifting snow conditions. In this case, those conditions may be considered to be part of the event.

In general, higher within-event LOS can be produced with an anti-icing strategy and relatively short operational cycle times of less than 1.5 hours. As cycle times increase, there are opportunities for higher accumulations of snow and ice on the roadway prior to plowing and retreating. Thus, maintaining an unbonded pavement/snow/ice interface becomes increasingly more difficult as cycle times increase.

For the purpose of the following discussion, pavement condition LOS is divided into three categories of low, medium, and high that can be related to pavement snow & ice condition (PSIC) defined in the following way:

Pavement condition LOS

PSIC

Low

5 and 6

Medium

3 and 4

High

1 and 2

With respect to after-event LOS, most agencies provide treatment until "bare" pavement is achieved. The measure of LOS then becomes the time, in hours, needed to reach a high LOS (a PSIC of 2 or 1). Again, for the purpose of this discussion, after-end-of-event LOS is divided into the three categories of low, medium, and high in the following way:

After-event LOS

Time (hr) to achieve a PSIC of 2 or 1

Low

>8.0

Medium

3.1-8.0

High

<3.1

Table 7 shows the expected LOS levels that can be achieved within- and after-winter weather events from various snow and ice control strategies and from tactics. For convenience, each strategy/tactic is described again below. It must be recognized that these are general approaches and changing conditions within an event often necessitate changes in strategies and tactics.

When selecting treatments, the most important consideration is LOS goals. Depending on a variety of factors, the goals may change during an event.

Every snow and ice control treatment should be individually designed to produce an effect that is consistent with the LOS goals,

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