Upon receiving this assignment, Supertramp assembled within seconds of the secret call and decided on a location to collect data (Burnet Ln. and Romeria Rd.) a "T" intersection located near Lamar Middle School. We chose this particular intersection because of the light's rediculous length and complete inconvenience.
The purpose of the lab is to determine the amount of time necessary to traverse the intersection, in order to estimate the safety of clearing the intersection at a reasonable speed once the yellow light commences.
Procedure
Initially, we determined the length of the yellow light by recording the light's duration on video. This allows us to record the length of time of the yellow light.
Then, we determined an approxiamate length of the intersection (using Google Earth) approxiamated because the intersection involves a left/right turn.
Thus, by recording the length and reasonable speed for traveling, we determined a reasonable deceleration while taking the turn, and the amount of time necessary to execute such a turn.
Mathematical Equations
x= vt
22m (Curve Length) = 8.9 m/s (Safe Speed 20 m.p.h.) x t (Seconds)
t = 2.47s
Acceleration x Time + Initial Velocity = Final Velocity
a(1.53) + 13.4 = 8.9
Acceleration = -2.94 (reasonable)
4-2.47 = 1.53
13.4 m/s = 30 m.p.h. (Speeding when light turns yellow)
X + 3.5 (Average Length of Car) = (1/2) (-2.94 m/s/s) (1.53)^2 + 13.4 (1.53)
-3.44 + 20.5 = 13.56
A 0.53 + 13.4 = 8.9
A= -8.9
Acceleration at -8.9 m/s/s is ridiculous, therefore we suggest the addition of at least 1 second to the yellow light.
Conclusion
The duration of the yellow light is unreasonable, and in order for a person to make the turn successfully they would have to decelerate a ridiculous amount, we will suggest to the city of Austin to extend the length of the yellow light, in order to encourage safety in our city.
http://maps.google.com/maps?hl=en&tab=wl
