WASHINGTON (CNN) - President-elect Barack Obama's January 17 train trip from Philadelphia to Washington - intended to make the inauguration the most open and accessible in history - is also presenting the U.S. Secret Service with miles and miles and miles of security problems.
The Presidential Inauguration Committee says that - in addition to well-publicized "whistle stops" in Philadelphia, Pennsylvania, Wilmington, Delaware, and Baltimore, Maryland - the public will have the opportunity to view the train at other locations along its 137-mile route.
But the committee thus far has not indicated where those sites will be, and the Secret Service has yet to release what security restrictions will be in place.
Security experts say the train ride presents traditional threats to the VIPs on board the train, including countless buildings, homes and warehouses along the route that could conceal snipers. And there are non-traditional vulnerabilities: scores of bridges and tunnels that could be sabotaged.
And, two environmental groups have warned, terrorists could take a page from al Qaeda's playbook, using existing infrastructure, in this case chemical plants along the route, as an attack method.
In a letter to the Secret Service, the groups - Greenpeace and Friends of the Earth - wrote they were worried that security efforts focused on the Obama entourage "might not extend to the larger community which may suffer serious consequences in case of even one moderately successful terrorist release of ultrahazardous chemicals."
"We will be urging Mr. Obama and Mr. Biden to re-consider" plans to travel by train, the groups wrote.
In response, Secret Service spokesman Eric Zahren told the groups, "Please be assured, the U.S. Secret Service is working closely with federal, state and local agencies to maintain a safe and secure environment for all of
Homeland Security Secretary Michael Chertoff, whose department includes the Secret Service, told CNN he is confident of the agency's abilities to protect the president-elect.
"Remember, the Secret Service has taken the president to Iraq and to Afghanistan - to some very hostile places around the world. I'm comfortable that we have the skills, working of course with state and local authorities, to protect the president-elect in Pennsylvania and Baltimore and Washington, D.C.," Chertoff said.
Chertoff said he is aware of environmental groups' concerns. "I suspect it's being done, frankly, largely as a public relations ploy," he said. "I don't think there's any particular threat from chemical plants along the train route."
A former Secret Service agent said the service has had experience with presidential train trips in the past and said authorities typically install chemical, biological and radiological detectors along the route.
Amtrak and the Secret Service will not say if Obama's train car will be armored, though experts say special cars have been used in the past.
"Security will be provided in the air, on the ground and in the water," said Amtrak Police Department Chief John O'Connor. "It's a daunting challenge, but there are many, many police departments that are working together to make this happen ... and planning is going very well."