Dealing with Bus Bunching A control tool, a pilot plan and a pedagogical game Juan Carlos Muñoz, Felipe Delgado, Ricardo Giesen Sergio Ariztía, Daniel Hernández, Felipe Ortiz and William Phillips Department of Transport Engineering and Logistics Pontificia Universidad Católica de Chile
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Dealing with Bus Bunching A control tool, a pilot plan and a
pedagogical game
Juan Carlos Muñoz, Felipe Delgado, Ricardo Giesen
Sergio Ariztía, Daniel Hernández, Felipe Ortiz and William Phillips Department of Transport Engineering and Logistics
Pontificia Universidad Católica de Chile
Santiago, Chile
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And so on so forth.
Our challenge: keep buses evenly spaced under an inherently unstable system
Now, if we want to prevent bunching from occurring … when is the
right time to intervene?
Bus bunching
Severe problem if not controlled
Most passengers wait longer than they should for crowded
buses
Reduces reliability affecting passengers and operators
Affects Cycle time and capacity
Put pressure in the authority for more buses
Contribution: Control Mechanism to Avoid Bus Bunching!
Approach
Based on real-time information (or estimations) about:
Bus position.
Bus loads.
# of Passengers waiting at each stop.
We run a rolling-horizon optimization model each time a bus
reaches a stop or every certain amount of time (e.g. 2 minutes)
The model minimizes:
Waiting for first bus + Waiting for subsequent buses + time held
Results: Simulation Animation
Simulation includes events randomness
2 hours of bus operation. 15 minutes “warm-up” period.
Encouraging simulation-based results
Excess waiting drops in over 60%
Excess Waiting for first bus drops in 80%
Waiting for second bus drops in 90%
Comfort inside buses improve significantly
Reliability for users improve significantly: waiting twice the average
interval drops from 1 out of 11 trips, to 1 out of 1250.
Cycle time drops by 4% and its variability by 35%
Common disobedience rate across drivers
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0%10%20%30%40%50%60%70%80%90%100%
Tota
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Tim
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in]
Obedience rate
HRT, Beta=0,5
Sin Control
Full disobedience of a set of drivers
8000
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0 1 2 3 4 5 6 7
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ime
[Min
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Deaf Buses from a total of 15 buses
Implementation
• The first pilot plan consisted in implemnting our holding
tool in buses of line 210 of SuBus from Transantiago
(Santiago, Chile) along its full path from 7:00 to 9:30 AM.
• We chose 24 out of 130 stops to hold buses
• One person in each of these 24 stops received text
messages (from a central computer) into their cell
phones indicating when each bus should depart from the
stop.
Plan Description
Control Points
The results were very promising even though the conditions were far
from ideal
Input Data
• Trajectories of given GPS data (on a regular day)
Fines due to regularity on that day dropped around 50%
The demand captured by the line grew!
• Line 210 captured an extra 20% demand!
94.000
96.000
98.000
100.000
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106.000
7.400 7.600 7.800 8.000 8.200 8.400 8.600 8.800
Demand for Line 210 (pax)
Demand on All lines
(pax)
This pilot plan can improve significantly
1) GPS errors can be corrected
2) Run the Optimization more often (from 3.5 to 2 min)
3) Calibrate speeds and arrival rates
4) Check data inputs before feeding the system
And more importantly:
5) Bypass the person at the stop. Communicate to drivers
Conclusions
Developed a tool for headway control using Holding in real time reaching
time savings of over 50%
Extending it to green time extension and boarding limits savings can reach
over 60% with only minor impact on car users
Huge improvements in comfort and reliability
The tool is fast enough for real time applications. It had been tested
successfully in simulations (for the Insurgentes corridor in Mexico city)
and in the streets (line 210 in Santiago, Chile) with very promising results.
Publications and working papers
• Delgado, F., Muñoz, J.C., Giesen, R., Cipriano, A. (2009) Real-Time Control of Buses in a Transit Corridor Based on Vehicle Holding and Boarding Limits. Transportation Research Record, Vol 2090, 55-67
• Munoz, J.C. and Giesen, R. (2010). Optimization of Public Transportation Systems. Encyclopedia of Operations Research and Management Science, Vol 6, 3886-3896.
• Delgado, F., J.C. Muñoz and R. Giesen (2012) How much can holding and limiting boarding improve transit performance? Trans Res Part B, , vol.46 (9), 1202-1217
• Muñoz, J.C., C. Cortés, F. Delgado, F. Valencia, R. Giesen, D. Sáez and A. Cipriano (2013) Comparison of dynamic control strategies for transit operations. Forthcoming in Trans Res Part C.
Pedagogical game
Yesterday we submitted a proposal to an innovation grant for US$500,000 (40% committed by a bus operator).