Database

markdown LimSim stores all data in the database during simulation to facilitate analysis and evaluation of simulation. LimSim uses a lightweight open-source database SQLite for data storage, which makes it easy to view and migrate data. The storage of simulation data in LimSim is mainly divided into three parts: road network data, vehicle data, and simulation data, which are introduced below.

Road Network Data

Based on the SUMO road network, LimSim models multiple types of road network structures. The following tables record road network data. When replaying data, the road network is reconstructed based on the following data.

edgeINFO

Field	Data Type	Description
id	TEXT PRIMARY KEY	ID of edge
laneNumber	INT	Number of lanes on edge
from_junction	TEXT	ID of starting junction of edge
to_junction	TEXT	ID of ending junction of edge

laneINFO

Field	Data Type	Description
id	TEXT PRIMARY KEY	ID of lane
rawShape	TEXT	Geometric structure of lane centerline
width	REAL	Width of lane
maxSpeed	REAL	Maximum speed of lane
edgeID	TEXT	ID of edge to which lane belongs
length	REAL	Length of lane

The rawShape of a lane is stored as a string in the database, separated by spaces and commas, respectively. For example, the following rawShape records three points, which are (10.2, 100.3), (14.3, 15.4), and (13.4, 12.6).

10.2,100.3 14.3,15.4 13.4,12.6

junctionLaneINFO

In the SUMO road network, there are two types of lanes, one is generated by the user with a specific name. The other is a lane automatically generated by SUMO to connect the first type of lane. These lanes have the property of internal. Here for convenience, we define the second type of lane as the junctionLane. The junctionLane always connects two lanes, and some junctionLanes also have the property of traffic signals.

Field	Data Type	Description
id	TEXT PRIMARY KEY	ID of junctionLane
width	REAL	Width of junctionLane
maxSpeed	REAL	Maximum speed of junctionLane
length	REAL	Length of junctionLane
tlLogicID	TEXT	ID of traffic signal control logic to which junctionLane belongs
tlIndex	INT	Number in the traffic signal control logic to which the junctionLane belongs

connectionINFO

As mentioned earlier, two lanes are connected by a junctionLane, and the connection records this connection relationship.

Field	Data Type	Description
fromLane	TEXT	ID of starting lane
toLane	TEXT	ID of ending lane
direction	TEXT	Direction, refer to XXXX
via	TEXT	ID of junctionLane that connects the two lanes together

junctionINFO

Field	Data Type	Description
id	TEXT PRIMARY KEY	ID of junction
rawShape	TEXT	Geometric structure of junction

Like the rawShape of a lane, the rawShape of a junction is also recorded as a string in the database, separated by spaces and commas, respectively. But the rawShape of the junction records the outer contour of the junction.

tlLogicINFO

Field	Data Type	Description
id	TEXT PRIMARY KEY	ID of traffic signal control logic, also corresponding to junction ID
tlType	TEXT	Type of traffic signal control logic, divided into static, actuated, and delay_based
preDefPhases	TEXT	Phases and order of traffic signal control logic, refer to XXX

trafficLightStates

Field	Data Type	Description
frame	INT	Current simulation time
id	TEXT	ID of traffic signal control logic
currPhase	TEXT	Current phase
nextPhase	TEXT	Next phase
switchTime	REAL	Remaining duration of current phase

Vehicle Information

Vehicle information is divided into two types: inherent attributes of vehicles and real-time status during simulation.

vehicleINFO

Field	Data Type	Description
vid	INT	ID of vehicle
length	REAL	Length of vehicle
width	REAL	Width of vehicle
maxAccel	REAL	Maximum acceleration of vehicle
maxDecel	REAL	Maximum deceleration rate of vehicle
maxSpeed	REAL	Maximum speed of vehicle
vTypeID	TEXT	ID of vehicle model
routes	TEXT	Route information for the vehicle

frameINFO

Field	Data Type	Description
frame	INT	Current simulation time
vid	INT	ID of vehicle
vtag	TEXT	Role of vehicle, can be ego, AoI, or outOfAoI
x	REAL	X position of vehicle at this moment
y	REAL	Y position of vehicle at this moment
yaw	REAL	Yaw angle of vehicle at this moment, with x-axis as a starting point and counterclockwise as a positive direction
speed	REAL	Speed of vehicle at this moment
accel	REAL	Acceleration of vehicle at this moment
laneID	TEXT	ID of lane in which the vehicle is located
lanePos	REAL	Distance from the starting point of the lane to the vehicle at this moment
routeIdx	INT	The number of the current section of the

Values processed

The above indicators have been normalized and are not real values. For more information, please refer to Scenario Evaluation.

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1. TTC(Time To Collision): refers to how long it will take for two vehicles to collide while they maintain their current speed. ↩