PCE15-M
PRINCIPLES OF
TRANSPORTATION ENGINEERING
Queueing Theory, Highway
Safety and Accident Analysis,
Service Rates and Traffic
Studies
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community
Ask the community for help and clear up your study doubts
University Rankings
Discover the best universities in your country according to Docsity users
Free resources
Our save-the-student-ebooks!
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
Traffic Studies and Intersection Design Principles, Slides of Transportation Engineering
Key principles for designing and improving intersections to enhance capacity and safety. It emphasizes avoiding common mistakes that lead to congestion or accidents. The guidelines cover aspects such as limiting the number of intersection legs, avoiding staggered intersections, maintaining straight traffic flow, ensuring adequate intersection angles, and spacing intersections appropriately. A formula for calculating the minimum distance between intersections based on design speed and number of lanes. This information is crucial for traffic engineers and urban planners involved in road network design and optimization, aiming to create efficient and safe transportation systems. Useful for understanding the fundamental considerations in traffic engineering and intersection design, providing practical insights for professionals and students in the field.
Typology: Slides
2023/2024
1 / 29
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Traffic Studies and Intersection Design Principles and more Slides Transportation Engineering in PDF only on Docsity!
PCE15-M
PRINCIPLES OF
TRANSPORTATION ENGINEERING
Queueing Theory, Highway
Safety and Accident Analysis,
Service Rates and Traffic
Studies
OUTLINE
I. Queueing Theory
II. Highway Safety and Accident
Analysis
a. Accident rates for 100 million vehicle
miles of travel for a segment of
highway
b. Accident rates per million entering
vehicles for an intersection
c. Severity ratio
III. Service Rates
IV. Traffic Studies
a. Basic Intersection Design Principle
b. Intersection Design Elements
c. Methods of Control of Intersection
d. Analysis of Unsignalized Intersections
e. Analysis and Design of Roundabouts
or Rotondas
f. Traffic Signal Control
Arrival Rate (λ) - The rate at which vehicles arrive at a queue Departure Rate (μ) - The rate at which vehicles leave the queue point
- or Service Rate Traffic Intensity (ρ) - The ratio of the arrival rate to the departure rate Queue Length - The number of vehicles waiting in line Waiting Time - The time each vehicle spends in the queue
QUEUING THEORY
Types of Queue
- Oversaturated queue are those arrival rate is greater than the service rate
- Saturated queue are those arrival rate is less than the service rate
Under-saturated infinite queues when both arrivals and service times are exponentially
distributed and there is one channel. For example, when the road is under repair on one
lane.
QUEUING THEORY
- D / D / 1 Due to the regularity of both arrivals and departures, it is more convenient to analyze a D/D/ 1 queuing system graphically. Arrivals and departures are easily represented by straight lines with the slopes corresponding to their rates.
- M / D / 1 The M/D/ 1 queuing system assumes that the arrivals of vehicles follow a negative exponential distribution, a probability distribution characterized by randomness.
QUEUING THEORY
a. Average length of queue
m =
b. Average waiting time
w =
c. Average time spent in the system
i =
- M / M / 1 The M/M/ 1 queuing system assumes negative exponential for both arrival and departure distributions.
QUEUING THEORY
a. Average length of queue
m =
b. Average waiting time
w =
c. Average time spent in the system
i =
Sample Problem A freeway has three lanes in each direction and has a maximum flow of 100 veh/min. It is operating at 50 veh/min. A collision occurs, blocking the two lanes and restricting the flow of the third lane to 25 veh/min. The freeway has a constant speed of 60 veh/hr and its three-lane jam density is 60 veh/m. The incident is completely cleared in 30 minutes and traffic returns to normal as soon this happened. a. Determine the length of queue 20 mins after the collision b. Determine the longest vehicle queue. c. In how may minutes will the queue dissipate? d. How may vehicles were affected by the accident? e. Compute the total delay due to the accident. f. What is the average delay per vehicle.
QUEUING THEORY
HIGHWAY SAFETY AND ACCIDENT ANALYSIS
Accident rates for 100 million vehicle miles of travel is a crucial metric in highway safety analysis. It helps in understanding the frequency of accidents relative to the amount of travel on a specific highway segment.
HIGHWAY SAFETY AND ACCIDENT ANALYSIS
Severity Ratio: :
Severity Ratio =
- f : fatal
- i : injury
- p : property damage
HIGHWAY SAFETY AND ACCIDENT ANALYSIS
Importance of Accident Rates :
- Safety Assessment : Helps identify high-risk areas.
- Resource Allocation : Guides where to focus safety improvements.
- Performance Measurement : Evaluates the effectiveness of safety interventions.
HIGHWAY SAFETY AND ACCIDENT ANALYSIS
Data Collection and Analysis :
- Crash Data : Collecting accurate crash data is essential.
- Traffic Counts : Measuring traffic volumes accurately.
- Geospatial Analysis : Mapping accident locations to identify patterns.
SERVICE RATES
Service rates refer to the speed at which a system can serve or process arriving entities, such as vehicles in a traffic system or customers in a queue.
SERVICE RATES
Service rates refer to the speed at which a system can serve or process arriving entities, such as vehicles in a traffic system or customers in a queue. Service rate is a crucial parameter in analyzing how efficiently resources are utilized, affecting wait times and congestion levels in transportation systems. It is usually expressed in units such as vehicles per hour or customers per minute.
SERVICE RATES
Service rates refer to the speed at which a system can serve or process arriving entities, such as vehicles in a traffic system or customers in a queue. Service rate is a crucial parameter in analyzing how efficiently resources are utilized, affecting wait times and congestion levels in transportation systems. It is usually expressed in units such as vehicles per hour or customers per minute.