Physics 2

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

A traffic light turns yellow as you enter an intersection… Can you stop on time….? Or take the risk to cross the intersection… Do you even have enough time to think before the light turns red?

Traffic Light Project

Messan Folivi & Ben Pham Mr. Johns Physics AP February 15, 2009.

Situation of Dilemma • A driver is said to be in a situation of Dilemma when the time of the yellow light is too short to make a decision. • The driver’s thought oscillates between stopping and crossing riskily the intersection…

Are our parish traffic lights spare us from that dangerous situation???

•Let’s find out…

Some recommended yellow light times.. Speed Limits 25 MPH --

Yellow Light timings… 3.0 s

30 MPH

3.5 s

35 MPH

4.0 s

40 MPH

4.5 s

45 MPH

5.0 s

50 MPH

5.5 s

55 MPH

6.0 s

These are some stopping distances according to the Louisiana Driver Manual

Let’s see what is really going on!!!! •

FIRST TRIAL Florida Blvd & Sherwood Forest Blvd Baton Rouge, LA 70815

• The length of the intersection: 90 feet • Yellow light timing: 5.86 s Trials

1

2

3

5.75

5.89

5.94

• Average: (5.75 + 5.89 + 5.94) / 3 = 5.86 s

• Speed limit: 55 mi/hr = 80.7 ft/s • Average yellow light time: 5.86 s • Total distances: the width of the intersection + length of the car + stopping distance = 90 ft + 17 ft + 216 ft = 323 ft • Time required: 323 ft / 80.7 ft/s = 4 s 4 s > the actual yellow light time  The driver is not in a situation of dilemma….

Our Second Trial • Coursey Blvd & S Sherwood Forest Blvd, Baton Rouge, LA 70816,

• The width of the intersection: 80 feet light timing: • Yellow Trials 1 2 3 4.56

4.63

4.82

• Average: (4.56 + 4.63 + 4.82) / 3 = 4.67

• Speed limit: 45 mi/hr = 66 ft/s • Yellow light time: 4.67 s • Total distances: 80ft + 17ft + 154ft = 251 ft • Time required: 251ft / 66ft/s = 3.8 s Once again we can conclude that the driver has enough time to cross the intersection before the red light.

Our third try • Goodwood Blvd & Sherwood Forest Blvd, Baton Rouge, LA 70815

Third intersection • The width of the intersection: 60 ft • Yellow light timing: 3.10 s

• Speed limit : 35 mi/hr = 51.3 ft/s • Yellow light time: 3.98 s • Total distances: 60ft + 17ft + 101ft = 198 ft .Time required: 198ft / 51.3 ft/s = 3.47 s 3.47> actual yellow light time ====

The Driver is in a situation of Dilemma • The driver doesn’t have enough time to cross the intersection……However, due to the slight difference between the two yellow times, he can make it by accelerating… • The wise decision is to slow down and stop…………

Our fourth trial • Old Hammond Hwy & Sherwood Forest Blvd Baton Rouge, LA 70815

Fourth intersection • The width of the intersection: 96 feet • Yellow light timing: Trials

1

2

3

4.85

4.96

4.86

Average: ( 4.85 + 4.96 + 4.86) / 3 = 4.89 s

• Speed limit: 45 mi/hr = 66 ft/s • Yellow light time: 4.89 s • Total distances: 96ft + 17ft + 154ft = 267 ft • Time required: 267 ft / 66ft/s = 4.05s The driver has time to cross the road… There is no situation of dilemma..

Conclusion • In our four trials, we only see a case with a situation of dilemma. • By adding a reaction time in which the driver thinks about what to do, almost all of our trials will contain a situation of dilemma.

• Again, The wise decision for the driver is to slow down and prepare to stop when a traffic light turns yellow… • Because we don’t know when the light will turn red and what can happen in the next second….Our life depends on it……

And unfortunately for us, we don’t have the power to…..