Measurement Methods of conducting Spot speed Studies

Measurement Methods of conducting Spot speed Studies

Measurement Methods ways of conducting spot speed Studies are divided into 2 main categories: Manual and Automatic. Spot speeds could also be calculable by manually measuring the time it takes a vehicle to travel between two defined points on the route a renowned distance apart (short distance,)usually below 90m. Distance between two points is mostly relying upon the typical speed of the traffic stream. the subsequent tables offer suggested study length (in meters) for numerous average stream speed ranges (in kmph) Following are some methods to live spot speed. of vehicles during a traffic stream, during which the primary two are manual ways and others is automatic:

Read More —— Speed Studies

1-Pavement markings

In this method, markings of pavement are placed across the road at each end of the trap. The observer starts and stops the watch as the vehicle passes lines. In this method, a minimum of two observers required to collect the data, of which one is standing at the starting point to start and stop the stopwatch, and another one is to stand at endpoint to give an indication to stop the watch when a vehicle passes the end line. Advantages of this method are that after the initial installation no set-up time is required, markings are easily renewed, and the disadvantage of this is that substantial error, is only applicable for low traffic conditions.


2-Enoscope or Mirror box

The endoscope consists of a simple open housing containing a mirror mounted on a tripod at the side of the road in such a way that an observer’s line of sight turned through 90o. The observer stands at one end of the section and on the other end, the endoscope is placed and measure the time taken by the vehicle to cross the section. Advantages of this method are that it simple and eliminate the errors due to parallax and considerable time is required to time each vehicle, which lengthens the study period and under heavy traffic condition it may be difficult to relate ostentatious to the proper vehicle are the disadvantages of endoscope method.

3- Road Detector (Pressure contact strips)

Pressure contact strips either gas or electric will be accustomed to avoid errors because of the optical phenomenon and due to manually beginning and stopping the chronometer or stopwatch. this can be the most effective technique over a brief distance it provides quite relevant knowledge and if it’s connected through a graphical recorder then it gives continuous data automatically.

4-Doppler-Principle Meters (Radar)

This is a recently developed method, it automatically records speed, employs a radar transmitter-receiver unit. The apparatus transmits high-frequency electromagnetic waves in a narrow beam towards the moving vehicle, and reflected waves changed their length depending upon the vehicle’s speed and returned to the receiving unit, through calibration gives directly spot speed of the vehicle.

5- Electronic-Principle Detectors (Photograp)

In this method, a camera records the distance a vehicle has traveled in a selected short period of time. This exposure of the photo must take place at a constant time interval and the distance traveled by the vehicle is measured by projecting the films during the exposure interval. Advantage of a method that provides a permanent record with 100% of the sample obtained. This method is widely used in developed cities. In this case we can use a VCR which will give a more accurate result.

Read More —————— Traffic Volume

spot speed

Data Presentation

With the above methods, the collected data must be presented in a representable form. This simplifies and simplifies the calculation and analysis. Use the following methods to represent point velocity data:

1-Frequency Distribution Table

After the collection of data in the given conditions, arrange the spot speed values in order to their magnitudes. Then select an interval speed (e.g. 5 kmph) and make a grouping of data that come under this range. Now, prepare the frequency distribution table.

2- Frequency Distribution Curve

Read More —————— VERTICAL CURVE

For each speed group, the percentage frequency of observations within the group is plotted against the mean speed (middle marking) of the group (s). The modal speed and the speed of the traffic flow can be determined from this curve. The shape of the curve follows the normal distribution curve since most vehicles on the road move near the average speed and very few deviate from the average speed.


3- Cumulative Frequency Distribution Curve

For every speed group, the percent accumulative frequency of observations is planned versus the {upper} limit of the speed group. The cumulative distribution curve, however, leads to an awfully helpful plot of speed versus the % of vehicles traveling at or below the selected speed. For this reason, the upper limit of the speed group is employed because of the plotting point. In each distribution curve, the plots are connected by a swish curve that minimizes the overall distance of points falling on top of the road and people falling below the line. A smooth curve is defined together without.

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