I'm connecting through IAD to PHL on a Thu evening later this month.

I come in on UA208 from SJC, on a Thu evening at 3.30 pm.

I am thinking of taking a flight out of DCA (instead of IAD) so that i can get a couple of 500-mile minimums before i reach PHL. i'm trying to see if i will have enough time to get from IAD to DCA and then take US2415 DCA-ORF at 4.40 pm (and later, US3788 ORF-PHL).

From this thread and the Metro site, it looks like it will take an hour by public transport, to get from IAD to DCA. Is there a faster way to get to DCA, from IAD? Cab? What's the traffic like at that time of the day? cost?

I will have only carry-on luggage. Considering i need to clear security at DCA and check-in, this seems a tall order.