If youre on a DART train, dont worry, you wont be in the dark. But, the Dallas Area Rapid Transit HQ will go dark (the lights in the restroom may stay on, if you need to go) for the sixth straight year between 8:30 and 9:30 p.m. Saturday night as part of Earth Hour 2013. DART leaders tell us the rapid transit system has numerous ways to preserve the environment. The latest: a new 40-foot compressed natural gas bus(pictured), which made its debut in January. It is the first of 459 to be placed into service over the next three years to replace older buses that have reached the end of their useful life, a DART spokesman tells us. Newmark Grubb Knight Frank property management services employees and clients also plan to power down equipment and lights during Earth Hour.

Are you going dark Saturday night to save the Earth or just to cuddle with your honey? tonie@bisnow.com