TRAFFIC STUDIES

Speed and traffic volume are an important consideration in highway transportation as it is related to safety, time, comfort and convenience of road users. The actual speed of vehicles may vary depending on several factors such as geometric features, traffic conditions, time, place, environment, and even drivers themselves.

SPOT SPEED STUDIES

Spot Speed studies are used to estimate distribution of speeds of vehicles in a stream of traffic at a particular location of highway. It is usually done after determining the number of vehicles passing through a section or small distance. The following are significant values in Spot Speed:

Average Speed- Arithmetic mean of all observed vehicle speeds

Median Speed- The speed at the middle value in a series of top speeds arranged in ascending order

Modal Speed - The speed value that occurs most frequently in the sample of spot speeds

ith Percentile Spot Speed - The spot speed value below which l percent of the vehicles travel

Pace - The range of speed that has the greatest number of observations

Standard deviation of speeds - The measure of the spread of individual speeds

Here's a sample problem showing how to compute for missing values using a given Spot Speed Data:

spot speed.pdf

VOLUME STUDY

Also termed as traffic flow survey, traffic volume studies are used to obtain data on number of vehicles passing through a point on any highway facilities within a specified time period. Depending on the anticipated use of data, the time period usually varies as little as 15 minutes. Traffic volume data is used to identify critical traffic flow time periods, and can determine the influence of large vehicles or pedestrians on vehicular traffic flow or document traffic volume trends.

In order to conduct volume studies, certain volume characteristics are needed. Here are some of the volume characteristics with sample problems which served as a learning material for us in solving activity on volume study.

Volume Study.pdf

ASSESSMENT TASKS IN CLO3

Activity on Spot Speed

Spot Speed_BARTOLOME (1).pdf

Activity on Volume Study

Volume Study_BARTOLOME (1).pdf

REFLECTION/S

Collecting data for spot speed and traffic volume are critical for predicting future trends of traffic flow in highways. I have learned that traffic volume studies enable us to determine the number, movements, and classifications of roadway vehicles in a given location. Additionally, it allows us to identify critical time periods and determine the influence of large vehicles or pedestrians in vehicular traffic flows. On the other hand, spot speed is also an important consideration in traffic studies, as it is highly related to safety, comfort, time and economics. It is truly vital for measuring variables that are needed in design and analysis of highway systems. Using the given speed distributions, will allow engineers to rigorously make speed-related decisions that will substantially improve traffic operations effectively.

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