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A pre-timed four phase signal has critical lane flow rate for the first three phases as 200, 187 and 210 veh/hr with saturation flow rate of 1800 veh/hr/lane for all phases. The lost time is given as 4 seconds for each phases. If the cycle length is 60 seconds, the effective green time (in seconds) of the fourth phase is __________
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- 14 to 18
- 12
- 18
- 14
Correct Option: A
Lost time, L = 4 × 4 = 16 s
| y1 = | = | |||
| s1 | 1800 |
| y2 = | = | |||
| s2 | 1800 |
| y3 = | = | |||
| s3 | 1800 |
| y1 + y2 + y3 = | = | |||
| 1800 | 1800 |
| Co = | ||
| 1 - y |
| ⇒ 60 = | (Co = 60 s) | |
| 1 - y |
∴ y = 0.517
y = y1 + y2 + y3 + y4
| 0.517 = | + y4 | |
| 1800 |
∴ y4 = 0.185
| G = | (Co - L) = | (60 - 16) = 15.745 s | ||
| y | 0.517 |
