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3 CHAPTER 2 LEVEL OF SERVICE Level of service (LOS) in the context of roadway snow and RECOMMENDED LEVEL OF SERVICE GOALS ice control operations is a set of operational guidelines and pro- cedures that establish the timing, type, and frequency of treat- A good way to define LOS is in terms of results at various ments. The maintenance actions are directed toward achieving points in time. Examples include maximum accumulation of specific pavement condition goals for various highway sec- snow on highways during a storm, absence of pack or bond tions. Examples of LOS for highways, roads, and streets under during a storm, bare/wet pavement (x) hours after end-of- snow and ice control conditions are given in AASHTO's event, plowed and sanded (x) hours after end-of-event, fric- "Guide for Snow and Ice Control" (5). How highway agen- tion number > (y) (x) hours after end-of-event, road plowed, cies characterize LOS, how they assign LOS goals, and how and road passable. they measure the performance of maintenance operations in achieving the LOS goals are very important topics. These are ASSIGNING LEVEL OF SERVICE GOALS briefly described below. There are two fundamental approaches for highway agen- cies to use when assigning their LOS goals. The first is to HOW AGENCIES CHARACTERIZE LEVEL evaluate existing resources and direct them toward providing OF SERVICE a balanced LOS on a priority of treatment basis. This is real- istically the more common approach. The second, and pre- There are several ways (singularly and in combination) ferred, approach is to assign pavement condition goals at by which highway agencies characterize the LOS they pro- intervals within and after a "design storm" of "X" inches of vide. These include level of effort, priority of treatment, snow per hour to the various priority elements of the high- types of treatments, and results in terms of pavement con- way system. Using this, and production rate (lane-miles per ditions at various points in time during and after snow and hour) of equipment (including deadheading and reloading) in ice events. both the plowing and materials spreading modes, the neces- The level of effort category includes assigning more peo- sary personnel and equipment can then be determined to pro- ple and equipment to higher priority routes, providing more vide the desired LOS. or less effort during certain time frames, varying the number of people and equipment providing treatment in relationship PERFORMANCE MEASURING OF LEVEL to the predicted severity of the event, and so on. OF SERVICE The priority of treatment category includes giving first and/or more frequent treatment to higher traffic routes, high A variety of performance measures are being tried and accident/problem locations, commercial/business locations, used relative to LOS. These include (in order of popularity) school bus routes, transit routes, health facilities, fire house pavement conditions (visual) at various points in time (some locations, and schools. Some highway agencies use a system agencies use pictorial reference templates as an aid to condi- of providing treatment on a highway priority basis whereby tion observers); performance indices that relate the amount the next lower category of highway is not treated until higher of time pavement areas are snow/ice covered to total storm category roads are in "satisfactory" condition. time (visual); report cards (customer satisfaction surveys); In the type of treatment category, the treatments at various and friction measurements at various points in time and rat- locations are specifically defined. Examples include sanding ing slipperiness at various points in time based on vehicle hills and intersections, plowing-only on certain roads, using handling characteristics. nonchloride or reduced chloride applications in certain areas, The visual approach appears to be gaining in popularity in anti-icing areas, pre-treating areas, applying chemicals only the United States and abroad. Examples of visual character- at the beginning and end of the event, and so on. ization of roadway surfaces include the following: