Transcript PowerPoint Template
Maryland Unconventional Intersection Design (MUID) A Design and Evaluation tool for Alternative Intersections
Xianfeng Yang, Yao Cheng, Gang-Len Chang, Minseok Kim, Saed Rahwanji
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Outline
Introduction UAID in Maryland Research Motivation Multi-stage analysis process
Planning evaluation Signal Optimization Operational Analysis
MUID framework MUID case study Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
UAID
UAID stands for Unconventional Arterial Intersection Design
Median U-Turn Illustration Continuous Green-T CTO Illustration
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
UAID in Maryland
Continuous Flow Intersection
Diamond Diverging Intersection
Superstreet Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
UAID in Maryland----CFI
Left-turning vehicles begin their turn several hundred feet ahead of the main intersection and move into separated lanes to the right of the opposing thru movement . The first CFI in Maryland on was opened in 2000.
MD210 & MD228, Accokeek Advantages of the CFI design include
fewer and separated movement conflicts fewer signal phases at the main intersection a higher green ratio for through and left-turn
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
UAID in Maryland----DDI
The through lanes are crossed for a short section between diamond ramp intersections and then cross back to be on the normal (right) side of the roadway.
MD 295 & Arundel Mills Blvd., Hanover (half DDI) The DDI has been simulated to provide
lower delays (more than 60%) fewer stops shorter queue lengths.
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
UAID in Maryland----Superstreet
Left turns from the arterial can make direct left turns onto the cross-street , but cross-street thru and left turn movements must use the directional U-turn crossover.
MD 3 & Waugh Chapel Rd., Odenton The advantages of the Superstreet include
reduced delay for arterial through-traffic and for one pair of left turns reduced stops for arterial through-traffic fewer threats to crossing pedestrians reduced and separated conflict points.
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Outline
UAID UAID in Maryland Motivation Multi-stage analysis process
Planning evaluation Signal Optimization Operational Analysis
MUID framework MUID case study Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Motivation
Benefits of UAID
Reduced delay Improved safety Reduced number of conflict points
Lack of effective analysis tools
for design evaluation for signal optimization
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Multi-stage analysis process
Planning Evaluation
Input
: Demand pattern Preliminary geometry design
Output:
Estimated delay Queue spill back locations Q/L ratios of each critical segment Signal Design
Input
: Demand pattern Detail geometry of intersections
Output:
Optimal offset Optimal green split and cycle length Operation Anlaysis
Input
: Demand pattern Detail geometry of intersections Signal settings
Output:
Accurate delay Time-dependant queue configuration Overall level of service
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Step 1: Planning Evaluation
This system computes the overall interchange delay, identifies the potential queue spillback locations and calculates the queue lengths in a UAID design with a set of empirical equations.
250
Why it is important to calculate the queue lengths?
200
Queue length
150
Queue/Link ratio
100
Delay
50 0 0 0.1
0.2
0.3
0.4
0.5
Average Queue-to-bay Ratio
0.6
0.7
0.8
0.9
1
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Step 2: Signal Optimization
For each type of UAID design, the system provides a special signal optimization model to account for their unique geometrical features
DDI: the interdependent relations between queues at a DDI’s closely-spaced intersections
Design signal progression using detailed geometry parameters
Synchronization of critical movements Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Step 3: Operational Analysis
Evaluate the results obtained from the previous steps with simulation
Traffic volumes Geometrical features Signal timings
Generate the network performance
Queue lengths on critical links Average delay Average number of stops
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Outline
UAID UAID in Maryland Motivation Multi-stage analysis process
Planning evaluation Signal Optimization Operational Analysis
MUID framework MUID case study Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID system framework
Contain the three steps
Integrate the functions
Be clear to the users
Input module Start a new project Design selection Demand Input Geometry parameter input Other information inputs Evaluation and Operation module Geometric design evaluation Traffic signal optimization Step 1 Step 2 Output module Result demonstration Report generation
Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Start a new design Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Demand input Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Geometry parameter input Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Design evaluation Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Signal optimization Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Parameter and result display Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
MUID Case Study
Report generation Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Conclusion
UAID improves traffic performance
A multi-stage analysis process is needed for UAID
A software to help traffic engineers design and evaluate is developed to response the need of a useful tool Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park
Q & A
Yao Cheng, Research Assistant [email protected]
University of Maryland, College Park Traffic Safety and Operation Lab Dept. of Civil and Environmental Engineering University of Maryland, College Park