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JUN. r.e10104 I;UI1-'1'1 LLNUT t)IUND <br /> Traffic engineers utilize two types of tables when considering . <br /> reaction distance. The first lists simple reaction distance and usually <br /> includes the time needed for seeing, braking, and stopping. The second <br /> allows for anticipatory reaction distance. When anticipatory time is added <br /> (the time it takes for a person to prepare to stop), more time and distance <br /> are needed to react. Tables 9 and 10 illustrate the two types of traffic <br /> engineering tables (Miller, '1977). Designers of highway directional signs <br /> know .how To use this type of information. A standard procedure is to <br /> make the keyword larger. Commercial sign designers, on the other hand, <br /> have not always understood these requirements. The size of a sign and its <br /> elements requires balancing between anticipatory and simple reaction <br /> distances. ' <br /> TABLr 9 ' <br /> SIMPLE REACTION DISTANCE <br /> Speed (mph) Reaction distance (ft.) Ilr <br /> 30 470 <br /> 45 7D0 j <br /> 55 825 j <br /> I <br /> Recommended height to distance ratio for letter <br /> 1" to 25 feet. (Optimum viewing conditions) <br /> �II <br /> Anticipatory Sight.Distance <br /> I� <br /> LL <br /> Anticipatory -sight distance is a relatively new concept in <br /> traffic control. The driver must have time to judge a situation before <br /> encoL4nTering it and take any necessary precautionary action. This is parti- <br /> cularly important at areas of potential hazard and at points requiring <br /> complex driver decisions such as at intersections, interchange exits, lane <br /> drops, railroad grade crossings, drawbridges, toll collecTion booths, design <br /> speed reduction zones, etc. In a complex situation, where the driver is <br /> presented with difficult choices, ordinary reaction distance may be totally <br /> inadequate and unsafe, <br /> Determining The Size Of A Sign 15S <br />