1. Traffic Light Simulation
Lynn Jepsen

2. Introduction and Background
Try and find the most efficient way to move cars through an intersection at different traffic densities
Want to see waiting time and queue length go down
Green light usage needs to go up
Many traffic simulations out there, but none that I have seen with a learning light

3. Hierarchy Light Algorithm Traffic Light Stores four directions
Simulation
Direction
Stores multiple lanes
* Changes lanes for Cars*
Lane
Stores Cars (can't overlap)‏
Deals with green/red/yellow light
Car
Remembers and Changes speed
Remembers space

4. Simulation

5. Simulation
Cars on each lane take up a certain number of spaces and have a certain speed at each instant
Speed and space is update every .1 sec along with graphics
Speed up when object in front is getting farther away but with a max. accel.
Slow down for red and most yellow lights
Use Java to show graphics

6. Light Algorithm (variables)‏
Wants to optimize efficiency
This is defined as queue length, wait time and green light usage
Independent variables are traffic density, cycle length (length of one cycle in intersection) and ratio (ratio of green light time in each direction)‏
Can NOT change traffic density

7. Light Algorithm Uses previous data (past ten cycles)‏
Matching traffic density
Finds out which cycle had the smallest wait time, queue length, and greatest green light usage
Later averages all three cycles
Does the same for ratio
Looking for the best combination
Some randomness to match randomness of the road
Should begin to hover around one combo

8. Graphs graph all three efficiency variables
north/south line and an east/west line
if the algorithm is really optimizing the intersection then the two lines are close to each other

9. Efficiency The intersection can only be so efficient
If there are just too many cars for the number of lanes, then the algorithm will not work as well as it would in a lighter traffic density
This is not an exact science. There are too many variables in effect here
Traffic flow is just too erratic to predict well
You can’t possibly minimize wait time to the point where no one waits

10. Results and Conclusions
The simulation looks realistic
Light algorithm does cause fewer backups
Not perfect, but it keeps things under control and doesn't allow huge spikes