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minor update
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toruseo committed Apr 26, 2024
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23 changes: 15 additions & 8 deletions uxsim/uxsim.py
Original file line number Diff line number Diff line change
Expand Up @@ -374,26 +374,32 @@ def __init__(s, W, name, start_node, end_node, length, free_flow_speed=20, jam_d
Notes
-----
Traffic Flow Model:
- The link model follows a multi-lane, single-pipe approach where FIFO is guaranteed per link and no lane changing occurs.
- Fundamental diagram parameters such as free_flow_speed, jam_density (or jam_density_per_lane), and number_of_lanes determine the link's flow characteristics. Reaction time of drivers `REACTION_TIME` is a grobal parameter.
- Real-time link status for external reference is maintained with attributes `speed`, `density`, `flow`, `num_vehicles`, and `num_vehicles_queue`.
Traffic Flow Model Parameters:
- Their definition is illustrated as https://toruseo.jp/UXsim/docs/_images/fundamental_diagram.png
- If you are not familiar to the traffic flow theory, it is recommended that you adjust only `free_flow_speed` and `number_of_lanes` for the traffic flow model parameters, leaving the other parameters at their default values.
Capacity and Bottlenecks:
- The `capacity_out` and `capacity_in` parameters set the outflow and inflow capacities of the link. If not provided, the capacities are unlimited.
- These capacities can represent bottlenecks at the beginning or end of the link.
Connection to Node Model:
- At the downstream end of a sending link, vehicles in all lanes have the right to be sent out, but FIFO order is maintained.
- At the upstream end of a receiving link, all lanes can accept vehicles.
Parameter Adjustments:
- Some traffic flow model parameters like `free_flow_speed`, `jam_density`, `capacity_out`, `capacity_in`, and `merge_priority` can be altered during simulation to reflect changing conditions.
Details on Multi-lane model:
- Link model:
- Multiple lanes with single-pipe model. FIFO is guaranteed per link. No lane changing.
- Links have a `lanes` attribute representing the number of lanes.
Expand All @@ -406,22 +412,23 @@ def __init__(s, W, name, start_node, end_node, length, free_flow_speed=20, jam_d
- Receiving links:
- All lanes at the upstream end of the link can accept vehicles.
Details on Fundamental diagram parameters (*: input, **: alternative input):
- *free_flow_speed (m/s)
- *jam_density (veh/m/LINK)
- **jam_density_per_lane (veh/m/lane)
- *lanes, number_of_lane (lane)
Details on Fundamental diagram parameters (+: input, ++: alternative input):
- free_flow_speed (m/s)+
- jam_density (veh/m/LINK)+
- jam_density_per_lane (veh/m/lane)++
- lanes, number_of_lane (lane)+
- tau: y-intercept of link FD (s/veh*LINK)
- REACTION_TIME (s/veh*lane)
- REACTION_TIME, World.reaction_time (s/veh*lane)
- w (m/s)
- capacity (veh/s/LINK)
- capacity_per_lane (veh/s/lane)
- delta: minimum spacing (m/veh*LINK)
- delta_per_lane: minimum spacing in lane (m/veh*lane)
- q_star: capacity (veh/s/LINK)
- k_star: critical density (veh/s/LINK)
- *capacity_in, capacity_out: bottleneck capacity at beginning/end of link (veh/s/LINK)
- *Node.flow_capacity: node flow capacity (veh/s/LINK-LIKE)
- capacity_in, capacity_out: bottleneck capacity at beginning/end of link (veh/s/LINK)+
- Node.flow_capacity: node flow capacity (veh/s/LINK-LIKE)+
"""

s.W = W
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