From: j@donotspam.me   
      
   liu  wrote in   
   news:a8600d2f-0ec4-466a-94c1-0df0c32f7b09@googlegroups.com:   
      
   > I noticed most intersections have multiple cameras on the top of the   
   > lights. I wonder does it detects the cars in the left turn lane. I   
   > noticed sometimes that if there is no car in the left turn lane, the   
   > left turn light would be skipped directly to show only the green light   
   > for straight line traffic.   
   >   
   > Someone told me that if you don't turn on the left turn signal, you   
   > would get ignored and not given the left-turn green light.   
   >   
   > Does anyone know if it's the case and whether traffic lights are smart   
   > enough to detect the needs for left turn signal?   
   >   
   > Thanks,   
   >   
      
   Around here they use sensors in the pavement to detect cars in the left turn   
   lane.  Sometimes they are programmed to turn on the turn arrow on alternate   
   cycles in case a vehicle is there that was not detected.   
      
   Some places use cameras on the lights to detect the flashing lights of   
   emergency vehicles to stop the traffic and let them pass.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)