Quick sketch on the train ride to Grand Central Station

Today I took the train to the city to run in Central Park and to meet some friends for a drink. On the way in, my train was delayed for a bit, so I tried out my new white pencil/grey-toned sketchbook combo. I found the pencil a little rough and uncomfortable, and I was hoping for more contrast, but here's my sketch while the train was held up for a few minutes: