30.3.3 - Journey speed
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Understanding Journey Speed
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Today, we're discussing journey speed! Can anyone tell me what journey speed represents?
Is it how fast we go during a trip?
Close! Journey speed is the effective speed between two points, including stops. It's an important metric in traffic flow analysis.
So, it's different from just the speed we see on the speedometer, right?
Exactly! That's why lower journey speeds can indicate conditions where vehicles stop frequently, affecting overall travel efficiency.
Calculating Journey Speed
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How do we calculate journey speed?
I think we divide the total distance by the total time, right?
That's correct! We can express it mathematically as Journey Speed = Distance / Total Time.
What if our journey speed is less than our running speed?
Good question! If journey speed is lower than running speed, it suggests frequent stops, which indicates less comfortable travel conditions.
Significance of Journey Speed
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Why do you think journey speed is significant for traffic engineers?
Maybe to improve routes and reduce congestion?
Correct! By understanding journey speeds, traffic engineers can make better decisions about road designs and traffic flow management.
And if we know where the speeds are slow, we can target improvements there.
Exactly! It's all about ensuring efficient and safe travel.
Introduction & Overview
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Quick Overview
Standard
Journey speed reflects the average speed of a vehicle between two points, incorporating both moving and non-moving time. It helps in assessing travel conditions and is crucial in traffic engineering, as lower journey speeds may indicate stop-go situations that can affect overall traffic flow.
Detailed
Detailed Summary
Journey speed is defined as the effective speed of a vehicle on a journey between two points, calculated as the distance divided by total time taken, including stop times. This metric is critical for understanding traffic conditions, as a journey speed that is lower than running speed suggests that the vehicle experiences stop-go conditions, which necessitate acceleration and deceleration. The uniformity of journey speed with running speed indicates comfortable travel conditions. Traffic engineers utilize journey speed data to analyze travel patterns, determine necessary improvements in transport infrastructure, and enhance overall roadway efficiency.
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Definition of Journey Speed
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Chapter Content
Journey speed is the effective speed of the vehicle on a journey between two points and is the distance between the two points divided by the total time taken for the vehicle to complete the journey including any stopped time.
Detailed Explanation
Journey speed measures how fast a vehicle travels over a complete trip, from the starting point to the destination. To calculate it, we take the total distance covered and divide it by the total time taken for the journey, which includes any stops. This means that journey speed reflects the actual conditions of travel which may include times when the vehicle is stopped or moving slowly.
Examples & Analogies
Think of journey speed like a trip you take in your car. If you are driving from your home to the grocery store, and you stop at traffic lights and take a while to find parking, your journey speed will be lower than if you cruised straight there without stopping. It's like measuring both the distance you traveled and how long it took, including any delays.
Implications of Journey Speed
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Chapter Content
If the journey speed is less than running speed, it indicates that the journey follows a stop-go condition with enforced acceleration and deceleration.
Detailed Explanation
When the journey speed is lower than the running speed, it suggests that the vehicle experiences frequent stops and starts. This could be due to traffic congestion, road conditions, or traffic signals requiring the driver to accelerate and then brake repeatedly. Such conditions can lead to less efficient travel, as it takes more time to complete the journey than simply maintaining a steady speed.
Examples & Analogies
Imagine you're driving in a busy city filled with red lights and heavy traffic. You accelerate from a stop every time the light turns green, but you frequently have to stop again. Your car's speedometer might show a higher speed when you accelerate, but your overall journey takes much longer because of all the stopping and starting. This scenario illustrates how journey speed can be affected by stop-go conditions.
Comparison of Speeds
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Chapter Content
The spot speed here may vary from zero to some maximum in excess of the running speed. A uniformity between journey and running speeds denotes comfortable travel conditions.
Detailed Explanation
In a typical journey, the individual speed at different points (referred to as spot speed) may show a wide range - for example, sometimes the vehicle might be stationary in a traffic jam, while at other times it might speed up to overtake slower vehicles. If journey speed aligns closely with running speed, it suggests that the journey is smooth and without many interruptions, indicating a more pleasant driving experience.
Examples & Analogies
Consider a bicycle ride through a park. If you can pedal continuously without stopping too much (like when there's just a gentle slope and few people in your way), your journey speed matches your running speed. However, if you have to frequently dismount or slow down because of pedestrians, and then speed up again, your journey speed will be much lower than your potential speed when cycling on an empty path.
Key Concepts
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Journey Speed: Represents the effective speed between two points including stop times.
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Running Speed: The average speed of a vehicle while it is in motion.
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Traffic Flow: Influenced by both journey speed and running speed, impacting roadway efficiency.
Examples & Applications
Example 1: If a vehicle travels 60 km between two points and takes 1 hour for the trip, including 15 mins of stops, the journey speed would be 60 km/h, as the total time (1 hour) includes the stop time.
Example 2: If vehicles often have a journey speed lower than their running speed, it may indicate stop-and-go traffic conditions.
Memory Aids
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Rhymes
Journey speed so sweet, includes stops on your feet!
Stories
Imagine a traveler on a road trip. They stop to eat and stretch, and consider that time when calculating how long they took to reach their destination.
Memory Tools
Remember 'J' for Journey includes 'J' for Journey speed and is adjusted for stops.
Acronyms
JST - Journey Speed Time includes all Stop periods.
Flash Cards
Glossary
- Journey Speed
The effective speed of a vehicle traveling between two points, factoring in total time including stops.
- Running Speed
The average speed of a vehicle while in motion, not including any stopped time.
- Traffic Flow
The flow of vehicles along a roadway; it's influenced by the journey and running speeds.
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