Is Green Bigger than Red?

Bridge construction is in progress on Highway #6 in the Qu' Appelle Valley.<br> There is room for single lane traffic past the construction area.<br> In lieu of human traffic controllers red/green lights have been installed at each end of the area.<br> The distance between the lights is 0.6 km and the speed limit is 60 km/h in this zone.<br> If the duration of the red lights is 3.0 minutes what is the maximum duration of the green lights?<br> Assume that the speed limit is followed exactly.