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Select the correct statement.
Traffic capacity is the ability of a road to accommodate traffic volume. It is expressed as the maximum number of vehicle in a lane or a road that can pass a given point in a unit time, usually an hour.
Which of the following is indicated by a warning sign?
Which of the following shows skewed and staggered form of intersection?
The entrance and exit curves of a rotary have
Vehicles leaving the rotary would accelerate to the speed of the radiating roads and hence the exit curves should be of larger radii than entry curves. Hence the pavement width at entrance curve will be higher than at exit curve as the radius of the former is less than the latter.
Maximum number of vehicles can be parked with
Angle parking or parallel parking may be allowed in the kerb parking. Angle parking may be at angle 30, 60 or 90 degrees. Angle parking accommodates more vehicles per unit length of kerb and maximum vehicles that can be parked is with an angle of 90 degree.
Desire lines are drawn based on
Desire lines are plotted which is a graphical representation prepared in almost all O and D surveys, Desire lines are straight lines connecting the origin points with destinations. The width of such desire lines is drawn proportional to the number of trips in both directions.
The PCU (passenger car unit) value for car on an urban road is
The PCU may be considered as a measure of the relative space requirement of a vehicle class compared to that of a passenger car under a specified set of roadway, traffic and other conditions. If the addition of one vehicle of a particular class in the traffic stream produces the same effect as that due to the addition of one passenger car, then that vehicle class is considered equivalent to the passenger car with a PCU value equal to 1.0.
Traffic flow equation for a section of road is u = 80 - 0.7 K where ‘u’ is the speed in kmph and ‘K’ is the density in vpkm (vehicles per km). The maximum expected flow is
Traffic flow equation:
u = 80 - 0.7k
Since flow, q = u · k = 80 k - 0.7 k2
During measurement in spot speed study, a total of 1000 vehicles were observed. 85 per centile and 15 percentile speeds were obtained as 40 kmph and 10 kmph respectively. The number of vehicles moving between speeds of 10 kmph and 40 kmph would be:
Percentile speed gives cumulative percentage of vehicle travelling at or below that speed.
Between 85 percentile and 15 percentile speed, 70% of vehicles will be travelling. So 700 vehicles have speed between 10 kmph and 40 kmph.
The difference between 85 percentile speed and 15 percentile speed gives quality of flow.