Wintertime road grime accumulation. Chicago Illinois USA. Febuary 2007.

I took this photo at the North Harlem Avenue CTA Blue line rapid transit and bus depot. This photograph was taken during the Febuary 2007 Chicago Deep Freeze. For several days, the outside temperatures remained below 10 degrees above zero Farenheight and would sometimes barely make it past the zero mark. Night time temperatures averaged around 10 to 15 degrees below zero. It was so cold, that many water main pipes had burst open under the city streets, and fire hydrants would sometimes freeze.
It was obviously way too cold to wash cars or motor vechicles in these conditions due to ice and freezing doors. It was approximately 4 above zero when I had taken this photograph on Chicago's northwest side at North Harlem and West Bryn Mwar Avenues during rush hour.
Notice the grimy filthy conditions caused from rock salt and road grime on the CTA Nova bus.