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A stopwatch spot speed study includes five key steps: 1. Obtain appropriate study length. 2. Select proper location and layout. 3. Record observations on stopwatch spot speed study data form. 4. Calculate vehicle speeds. 5. Generate frequency distribution table and determine speed percentiles.
A convenient way to determine speed percentiles is a frequency distribution table. An example, with an explanation of how to use it, is provided in Appendix H. 10 mph (16 km/h) Pace. The speeds of individual vehicles on a highway vary. Speed dispersion refers to this spread in vehicle speeds.
Spot speed data refers to measurement of individual speeds of vehicles passing a point on a roadway. Care must be taken to conduct the study appropriately so that the sample data will adequately reflect speed characteristics of the population.
INTRODUCTION. The intent of spot speed studies are to record speed characteristics under prevailing traffic. conditions at a specific location along a roadway. The many applications of spot speed studies. include, but are not limited to, the following: •. Determine existing roadway speeds, for potential use in speed zoning and prioritization.
Spot speed studies are conducted to estimate the distribution of speeds of vehicles in a stream of traffic at a particular location on a highway. The speed of a vehicle is defined as the rate of movement of the vehicle; it is usually expressed in miles per hour (mi/h) or kilometers per hour (km/h).
Methods of Measuring Spot Speeds: The methods available for spot speed measurement may be classified as: 1. Direct observation of the time taken by a vehicle to cover a known distance. 2. Radar speedmeter method. 3. Electronic meter method . 4. Photographic methods.
The posted speed limit should be rounded to the nearest 5 miles per hour to the 85th percentile or 10-miles per hour pace, whichever is less. (whichever is less) by more than 3 miles per hour. For a more detailed discussion on posted speeds, please refer to Sectio.
