Purpose of a traffic census: among common traffic engineering studies, which one is the principal objective of conducting a traffic census?

Introduction / Context:
Traffic engineering employs several field studies to understand how roads are used. The term “traffic census” traditionally refers to counting vehicles to quantify usage patterns over time.

Given Data / Assumptions:

• Traffic census = periodic vehicle counts on a link or at a station.
• Objective is to estimate traffic volume, composition, and temporal variation.
• Other studies (speed–delay, parking, O–D) are specialized and use different methods.

Concept / Approach:
A traffic census is fundamentally a traffic volume study. It provides Annual Average Daily Traffic (AADT), peak-hour volumes, vehicle classifications, and growth trends needed for planning, design, and strengthening decisions.

Step-by-Step Solution:

Verification / Alternative check:
Design standards reference traffic census data for capacity analysis, pavement design, and warrants for control devices.

Why Other Options Are Wrong:
Speed–delay studies measure travel times and causes of delay; parking studies quantify on/off-street parking demand; O–D surveys track trip patterns. They are not synonymous with a census.

Common Pitfalls:
Assuming one survey type substitutes for another; mixing up traffic counting with O–D cordon surveys.

Final Answer:
traffic volume study