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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.
Spot speed data are gathered using one of three Methods: (1) stopwatch method, (2) radar meter method, or (3) pneumatic road tube method. These methods are described in this chapter in order from least expensive to most expensive.
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).
Learning Objectives. Determine following characteristics of spot speed. mean, median, mode, pace, 85th percentile, Fit a speed distribution. Check for normality. Comparison of assumed versus observed distribution. Introduction. Speed data is needed for a variety of traffic analyses.
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. Speed: the rate of movement of a vehicle (mi/h) or (km/h).
Spot speeds are useful to study paints of congestion, for locating traffic signals, or for enforcing speed limits. Running speeds are useful to assess the traffic capacity of highways. Journey speeds are useful to assess the adequacy of an existing road network as also the efficiency of the improvement measures and for cost-benefit studies of a ...
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.
