12:34 p.m. Time for a speed test -- 4.32Mbps down, 0.30Mbps up -- train slows down due to congestion in Groton, Conn. Stays on bridge for several minutes, allowing me to upload blog posts and photos without worry.

12:57 p.m. The train is moving quickly, I have three bars of 4G coverage. Test shows 1.07Mbps down, 1.33Mbps up -- that's never fun, when uploads are faster than downloads.

12:58 p.m. Back to 3G -- from here until 1:30 p.m., we get spotty coverage, but it does seem to stay at 4G for the rest of the trip.

2:02 p.m. Still on 4G, but speeds aren't really that great. Finished trying to write blog posts, just checking email and surfing the Internet -- no heavy lifting.

2:13 p.m. Arriving in Stamford, Conn. 4G speeds OK. 2.15Mbps down, 0.96Mbps up.