I was walking up a highway going uphill. Just ahead of me I saw the father (age 50) of a childhood playmate of mine. He had a tank strapped to his back. From the tank ran a hose to the bottom part of a broom which he was sweeping the highway with. The water from the tank would come out of the hose just at the bristle of the broom so as he swept he also washed the highway. I took the contraption and started sweeping the highway. I couldn't understand why the highway could be dirty since it had rained two nights previously. Then I remembered that it had snowed the night previously. This seemed to explain to me why the highway was so dirty.