Amtrak says it has restored train service to Newark Liberty International Airport. But the railroad said Wednesday that service to and from New York's Penn Station was still not operating because train tunnels under the Hudson and East rivers are flooded. Northeast Regional service between Newark, N.J., and Boston and Acela Express service for the length of the Northeast Corridor remain suspended with no date set for resumption. Amtrak is providing modified Northeast Regional service between Newark and points south, including restored service in Virginia. Keystone service in Pennsylvania and modified Downeaster between Boston and Portland, Maine service are also operating. Empire service between New York City and other cities in the state, and Canada was still out of commission.