---
title: "Short note: fixed and operational delay"
subject: "Transportation Engineering II"
chapter: 1
key: "semester_7/transportation_engineering_ii:short-note-fixed-operational-delay"
source: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/short-note-fixed-operational-delay
site: BCT Engineering
---

# Short note: fixed and operational delay

Transportation Engineering II · Chapter 1: Traffic Engineering

- Asked in: 2068 Baisakh, 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/transportation_engineering_ii/short-note-fixed-operational-delay
- Whole chapter: https://www.bctengineer.com/md/semester_7/transportation_engineering_ii/chapter-1

## Question

Write a short note on fixed delay and operational delay.

## Short answer

Fixed delay is caused by traffic control devices and is independent of volume; operational delay comes from traffic interactions like weaving or slow vehicles and grows with volume. Total delay is their sum, measured as stopped-time or travel-time delay.

## Answer

**Delay** is the extra travel time lost compared with free travel; it is a measure of the level of service of an intersection or road section. Total delay has two parts.

**Fixed delay**
- Caused by traffic control devices or physical features and not by other vehicles. It occurs even when there is no interference from other traffic.
- Examples: stopping at a traffic signal, stop sign, railway level crossing, toll plaza or check post.
- It is largely independent of traffic volume; at a signal it depends mainly on the cycle length and green split.

**Operational delay**
- Caused by interference of one component of traffic with another, so it grows with traffic volume.
- Examples: side friction from pedestrians and parked or stopping vehicles, slow vehicles, turning vehicles, merging and weaving, and queuing behind accidents.

$$
\text{Total delay} = \text{Fixed delay} + \text{Operational delay}
$$

Delay is commonly measured as **stopped-time delay** (time the vehicle is standing still) and **travel-time delay** (difference between the actual and the ideal travel time); both fixed and operational causes contribute to these. They are measured by the floating-car method or by a stopped-delay (point sample) study and are used to evaluate the level of service and the benefit of improvements.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is a fixed delay?
   A. Waiting behind a slow vehicle
   B. Stopping at a traffic signal
   C. Side friction from parked vehicles
   D. Queue behind an accident
   Answer: B. Fixed delay is caused by control devices or physical features such as signals, level crossings and toll plazas. (Key point: Fixed delay)

2. What causes operational delay?
   A. Interference between components of traffic, growing with volume
   B. Traffic signals only
   C. Pavement colour
   D. Driver licensing
   Answer: A. Pedestrians, parked or slow vehicles, turning and weaving create interference delay. (Key point: Operational delay)

3. How is total delay expressed?
   A. Fixed delay x operational delay
   B. Fixed delay + operational delay
   C. Fixed delay - operational delay
   D. Operational delay only
   Answer: B. Total delay is the sum of the two parts. (Key point: Total delay)