Traffic Control Speed Formulas and Percentiles Quiz

Test your knowledge on average speed, percentiles, coefficient of variation, and more in traffic engineering with this quiz.

Practice Learn Test

Which of the following formulas is used to calculate the average speed?

Average speed = Distance / Time

Average speed = Time / Distance

Average speed = Distance × Time

Average speed = Time × (Distance / 2)

What is the 85th percentile speed?

The speed at which 85% of the vehicles are traveling at or below

The speed at which 85% of the vehicles are traveling above

The speed at which 15% of the vehicles are traveling at or below

The speed at which 15% of the vehicles are traveling above

What is the formula to calculate the 85th percentile speed?

85th percentile speed = (Total number of vehicles × 0.85)th vehicle's speed

85th percentile speed = (Total number of vehicles × 0.15)th vehicle's speed

85th percentile speed = (Total number of vehicles × 0.85)th vehicle's speed + (Total number of vehicles × 0.15)th vehicle's speed

85th percentile speed = (Total number of vehicles × 0.15)th vehicle's speed - (Total number of vehicles × 0.85)th vehicle's speed

In a study, the 85th percentile speed is found to be 60 mph. What does this mean?

85% of the vehicles are traveling at or below 60 mph

15% of the vehicles are traveling at or below 60 mph

85% of the vehicles are traveling above 60 mph

15% of the vehicles are traveling above 60 mph

Which of the following factors affect the 85th percentile speed?

Road design

Traffic volume

Weather conditions

All of the above

In traffic studies, what does the term 'speed dispersion' refer to?

The variation in speeds among vehicles

The spread of vehicles on the road

The difference between the mean and median speeds

The randomness in vehicle speeds

What is the purpose of using speed percentiles in traffic analysis?

To determine the average speed of vehicles

To identify the fastest vehicle on the road

To understand the distribution of speeds

To calculate the travel time between two points

Which speed percentile is often used as a benchmark for setting speed limits?

50th percentile

85th percentile

25th percentile

95th percentile

What is the 15th percentile speed?

The speed at which 15% of the vehicles are traveling at or below

The speed at which 15% of the vehicles are traveling above

The speed at which 85% of the vehicles are traveling at or below

The speed at which 85% of the vehicles are traveling above

#10

What is the formula to calculate the coefficient of variation of speeds?

Coefficient of variation = Standard deviation of speeds / Mean speed

Coefficient of variation = Mean speed / Standard deviation of speeds

Coefficient of variation = Mean speed × Standard deviation of speeds

Coefficient of variation = Standard deviation of speeds - Mean speed

#11

How does the coefficient of variation value indicate speed distribution?

Higher coefficient of variation indicates more uniform speed distribution

Higher coefficient of variation indicates less uniform speed distribution

Coefficient of variation does not indicate speed distribution

Coefficient of variation indicates average speed only

#12

What does it signify if the coefficient of variation value is close to zero?

Uniform speed distribution

Highly variable speed distribution

Normal speed distribution

No conclusion can be drawn

#13

In traffic engineering, what is the 'trailing speed'?

The speed at which a vehicle is following another vehicle

The speed at which a vehicle is overtaking another vehicle

The speed at the rear end of a traffic queue

The average speed of vehicles at a signalized intersection

#14

Which parameter is NOT used in determining the 85th percentile speed?

Speed of the fastest vehicle

Speed of the slowest vehicle

Speed of the median vehicle

Speed of the 85th percentile vehicle