I used to take first street on the west side of union station north to the NoMA (I call it Dodge City after the Strava segment), but it’s now completely impassable. So I go around Columbus Circle to the East side of Union and up that street until it dead ends, take a left, and then go under the Harris Teeter parking garage to get to work: http://app.strava.com/activities/75857444
OR you can go up capitol hill to get on the same street: http://app.strava.com/activities/80473386
OR you can take K street across to get to the NoMA: http://app.strava.com/activities/76177301
Good luck!