NetLogo User Community Models
(back to the NetLogo User Community Models)
by Ales Janota
WHAT IS IT?
The model shows operation of a level crossing installation. The macro-level pattern emerging from interconnections of micro-level behaviours of agents should ensure such conditions of operation that the longest and slowest road vehicle finding itself at the crossing (i.e. inside the hazardous area) just at the moment of activating warning lights (triggered by detection of an approaching train) is able to leave this area before the barriers are falling down.
HOW IT WORKS
The model uses rules commonly accepted at crossings of roads and railway lines and enables to study effects of different conditions on traffic flow. Generating of new road vehicles depends on the set time-interval; each vehicle slows down if another vehicle appears ahead, otherwise it tries to go with a maximum allowed speed. The value of maximum speed allowed in front of the crossing may be reduced by installed traffic sign(s) to 20 km/h (independently for both directions). Time before detection of an approaching train and barriers' falling down depends on speed of the train.
HOW TO USE IT
1. Set up the model for selected positions of control elements (mentioned below) by pushing the "Setup” button.
2. Push the “Go” button (for continuous running) or “Go-step” button (for step by step running ).
3. Observe how selected settings influences the traffic flow.
THINGS TO NOTICE
Complex view at the operation of level crossing installation. Several principles taken over from models referenced below.
THINGS TO TRY
a) You may use the next control elements to setup the model:
- “Time_interval“ slider (to set a time interval between 2 generated road vehicles);
- “Max_car_speed” slider (to set a maximum speed for road vehicles going in both directions);
- “Train_speed” slider (to set the maximum speed of the train);
- “No_of_train_units” slider (to set a number of vagons /drawn as locomotives/ forming a train, particularly 1, 2 or 3);
- “TrafficSignL?“ switch (to create a traffic sign restricting the speed of road vehicles approaching the level crossing from the left side to 20 km/h)
- “TrafficSignR?“ switch (to create a traffic sign restricting the speed of road vehicles approaching the level crossing from the right side to 20 km/h)
b) The following indication parameters are available to show results of model run:
- Total cars passed (for each direction, and totally);
- Car throughput (for each direction, and totally);
- Current number of cars on the screen;
- Plot „Throughput vs time“;
- Elapsed time.
The model also utilises a variable time period used to close barriers. Its value depends on the current speed of a train approaching the level crossing (simplified to two stages - trains with a the speed <= 40 km/h and trains with the speed > 40 km/h).
Cars are generated for each direction (based on testing occupancy/vacancy of edge patches) and killed before reaching an edge of the world.
EXTENDING THE MODEL
Making model more realistic:
- try to substutite rectangular representation of railway line with arc;
- try to substitute used symbols (barriers, warning ligths,..) with symbols recommended by your national standards;
- try to make trains running in both directions;
- try to use more precise logic to substitute 2-step compensator of approach time based on train speed;
- try to create longer trains (consisting of locomotive + wagons, not only locomotives);
- try to add sound to simulate ringing bells in the warning period (is it possible?)
Commonly used features - nothing special.
The following references can be used to find other models from a traffic domain:
1. WILENSKY U., NetLogo Traffic Basic model. http://ccl.northwestern.edu/netlogo/models/TrafficBasic. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL, 1997.
3. WILENSKY U., NetLogo Traffic2 Lanes model. http://ccl.northwestern.edu/netlogo/models/Traffic2Lanes. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL, 1998.
6. WILENSKY U., NetLogo Gridlock model. http://ccl.northwestern.edu/netlogo/models/Gridlock. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL, 2002.
7. WILENSKY U., STROUP, W. NetLogo HubNet Gridlock model. http://ccl.northwestern.edu/netlogo/models/HubNetGridlock. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL, 2002.
8. DRESNER K., STONE, P. Multiagent Traffic Management: A Reservation-Based Intersection Control Mechanism. In Proceedings of the Third International Joint Conference on Autonomous Agents and MultiAgent Systems, p. 530--537, ACM. 2004
CREDITS AND REFERENCES
This model was presented at the 5th International Conference "TRANSPORT SYSTEMS TELEMATICS" organized by the Silesian University of Technology, Faculty of Transport in Katowice-Ustron, Poland, November 3-5, 2005 and published in the scientific journal:
JANOTA Ales, RASTOCNY Karol, ZAHRADNIK Jiri: Multi-Agent Approach to Traffic Simulation in NetLogo Environment - Level Crossing Model. Zeszyty Naukowe Politechniky Slazskiej, TRANSPORT z. 59, nr kol. 1691, Gliwice 2005. (pp.181-188) PL ISSN 0209-3324
http://fel.utc.sk/~janot/dokumenty/TST05-Janota.pdf - the PDF version of the paper;
http://fel.utc.sk/~janot/dokumenty/TST05-Janota-full.pdf - the PDF version of the presentation;
http://fel.utc.sk/~janot/dokumenty/LevelCrossing.nlogo - this model.