There is no runway 29 at Logan International, which Cliff says they reroute weather to in foggy weather. Logan has the following runways: 4/22 (left and right), 9/27, and 15/33 (right and left). (There's also now a runway 14/32 which was opened in 2006.) Also, the choice of runways used are generally based on current wind direction, not fog (which will most likely ground flights).