New York city expects to have the N and R subway lines, which run along the east side of the World Trade Center site, back in service in about six months. But the news isn't as good for the devastated 800-ft-long stretch of the 1 and 9 IRT subway tunnel, several feet under ground zero. It could take years to rebuild, say officials, and may even include a new alignment and station, depending on the future plan for the site above. Restoring service on the flooded PATH tubes to New Jersey largely depends on rebuilding the collapsed station in the middle of the basement of the WTC.

Since the Sept. 11 terrorist attack, engineers have been drawing up emergency shoring, bracing and tunnel cut-off plans for the two city transit lines and the PATH tubes, and contractors have been implementing them. The emergency New York City transit work alone could cost an estimated $2 million to $4 million, says Mysore Nagaraja, the New York City Transit Authority's chief engineer.

Nagaraja expects the rebuilding of the IRT tunnel to be funded through the city's $20-billion federal relief package but he won't hazard a guess as to the price tag. "It would be very difficult right now to come up with any meaningful cost estimate," he says. "Engineers are looking at all the options, and when we get the funding, we can proceed. The alignment of the future cut-and-cover tunnels will likely change," he adds.