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SECTION 3 Selecting an Appropriate Treatment 3.1 Introduction There are a variety of treatments with the potential to reduce vehicle speeds at high-speed intersections. This section provides information about these treatments, including their applicability, cost, secondary impacts, implementation considerations, and potential to effec- tively reduce speeds and increase safety. This information was compiled from a variety of national and international sources. However, there are very little data that clearly quantify how effectively these treatments reduce speeds at high-speed intersections. Furthermore, there are relatively little data on the safety performance of potential treatments and, when information is provided, there is no direct correlation to the change in safety caused by reduced speeds. Quantifying the safety effects of speed reduction treatments at high-speed intersections will require conditions to be monitored for a number of years after the treatments are implemented. The information provided in this section highlights the considerations that will help deter- mine which treatments may be appropriate at a specific location. In many cases, one or more treatments may be appropriate for a given intersection. To determine the most appropriate treat- ment, the information provided in this section must be balanced with local practices and engi- neering judgment related to the specific situation. The treatments covered by the Guidelines include those commonly used in the United States, those currently being researched, and those for which there was an expressed interest by state highway agencies. National use and interest in the treatments was determined through a national survey of state highway agencies conducted as part of the research efforts for NCHRP Project 3-74. More information about the survey and the responses can be found in NCHRP Web-Only Document 124. Some of the treatments included in the Guidelines have had limited or no documented appli- cation at high-speed intersections; however, their functions indicate they have potential to be applied at certain high-speed locations. For example, speed tables are generally used in low-speed residential environments, but they may be able to be applied at the stop-controlled approaches of high-speed intersections to reinforce the need to decelerate in advance of the intersection proper. Additionally, many of the treatments included in the Guidelines can be applied in both high- speed and low-speed environments. Identifying a treatment as a "high-speed" treatment does not imply it is inappropriate for low-speed applications. 15