Traffic Light Simulation

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
Simulation

• Simulation that obeys most rules of the road

4
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

5
Light Algorithm

• Wants to optimize efficiency (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
• Uses previous data (relationships of all 5
  variables) too pick best cycle length and ratio

6
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

7
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.
• You cant possibly minimize wait time to the
  point where no one waits.
• Traffic flow is just too erratic to predict well.

8
Multiple Lanes

• now includes multiple lanes in any direction
• has little other effect on the light algorithm
• increase the yellow light time when there are too
  many lanes
• next task make it so that cars can change lanes

9
Results and Conclusions

• The simulation looks realistic
• Light algorithm does cause fewer backups
• lots more lanes does not effect light algorithm,
  so it is still useful