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Selecting an Appropriate Treatment 27 3.5.7 Documented Applications, Speed Effects, and Safety Effects The columns for documented applications, speed effects, and safety effects in Exhibit 3-6 describe the tested applications for which the listed documented speed and safety effects were achieved. This information should be considered to determine the extent of research and data on a particular treatment and to identify similarities and differences in the tested applications that may produce similar or dissimilar effectiveness in a candidate site under consideration. 3.5.8 Key Considerations Many treatments are likely to have significant impacts on multimodal users, site-specific maintenance considerations, and/or other issues that should be considered as part of the screen- ing process. These secondary impacts may be limiting factors depending on the context for installation. For example, maintenance concerns related to snow removal will be significant in some environments and insignificant in others. Conditions in which particular treatments are not advised also are key considerations. 3.6 Treatment Evaluation Monitoring and evaluating the effectiveness of treatments can provide valuable data and feed- back for determining appropriate treatments for future applications. 3.6.1 Speed Monitoring Speed monitoring is the most direct way to evaluate the effectiveness of a speed reduction treatment. To evaluate speed effects, before-and-after data should be collected and compared. Driver acclimation effects can be expected with many of the treatments; therefore, the after-data collection should be targeted to identify both short- and long-term effectiveness. Speed moni- toring can also be used to evaluate how effective treatments are under particular weather or light- ing conditions. Data collection efforts should consider the driver behavior desired on the intersection approach, and should target data collection to determine to what extent the desired behavior has been achieved. In most cases, speed reduction is desired not only at the intersection proper, but on the approach as well. Collecting speed data at several points on an intersection approach will give the best picture of drivers' deceleration curves (a speed profile) as they respond to the treat- ment(s) approaching the intersection. Appendix B identifies the speed data collection points for several case studies. Additional information about speed testing programs can be found in the testing results section of NCHRP Web-Only Document 124. 3.6.2 Safety Monitoring As stated repeatedly in these Guidelines, there are no data to support the use of speed as a sur- rogate for safety or vice versa. An improved safety record based on implementing one or more of these treatments does not necessarily indicate that speeds were reduced. Nevertheless, safety is a critical concern for transportation professionals, and monitoring the safety effects of these treatments may be desirable. Safety effects must be monitored and analyzed over a period of several years before any sig- nificant conclusions can be drawn. Crashes are infrequent events and extensive data are needed to evaluate improvements in safety performance.