WASHINGTON (Reuters) – Al Qaeda considered attacking the U.S. rail sector on the 10th anniversary of the September 11 attacks, U.S. government officials said on Thursday in describing intelligence from Osama bin Laden's hide-out in Pakistan.

They said some evidence was found indicating the al Qaeda leader or his associates had engaged in discussions or planning for a possible attack on a train inside the United States on September 11, 2011.

"We have no information of any imminent terrorist threat to the U.S. rail sector, but wanted to make our partners aware of the alleged plotting," spokesman Matthew Chandler said of an intelligence message the Department of Homeland Security sent on Thursday.

The department and other U.S. agencies have been reviewing the treasure trove of information from bin Laden's compound in Pakistan seized by the United States during the raid this week that killed the al Qaeda leader.

An initial review of the information by U.S. intelligence analysts indicates that bin Laden, while in Abbottabad, played a direct role for years in plotting terror attacks, and was not just an inspirational figure to al Qaeda, The New York Times reported on Thursday.

"He wasn't just a figurehead," the Times quoted a U.S. official as saying. "He continued to plot and plan, to come up with ideas about targets, and to communicate those ideas to other senior Qaeda leaders."

The information on plotting against the U.S. rail sector indicated one possible tactic for attacking a train was trying to tip it somehow off its tracks, one official said.

The official said it appeared from the information that this was an idea that bin Laden or his associates considered, but there was no indication now from the intelligence that further plans were drawn up for the scheme or that steps were taken to carry it out.

Another official said al Qaeda in February last year contemplated the rail attack to occur on the 10th anniversary of the hijacked plane attacks on the World Trade Center in New York and the Pentagon, but the group was not tied to that exact date.

Since the raid, the Department of Homeland Security has taken a number of steps in reviewing measures at all potential terrorist targets, including transportation systems across the country. It added more officers at airports and at the borders.

Chandler said the alleged al Qaeda plot was based on "initial reporting, which is often misleading or inaccurate and subject to change."

He added, "We remain at a heightened state of vigilance," but said there were no plans to raise the national threat level.

Officials have long been concerned that al Qaeda might try to carry out attacks on the U.S. rail system.

In 2008, U.S. authorities warned of a possible al Qaeda threat to transit systems in and around New York City over the Thanksgiving holiday weekend.

Last year, an Afghan immigrant pleaded guilty in New York to plotting a suicide bombing campaign on Manhattan's subway system in what U.S. authorities described as one of the most serious threats since the September 11 attacks.

(Editing by Mohammad Zargham and Vicki Allen)

MEMPHIS, Tenn (Reuters) – The rising Mississippi river lapped over downtown Memphis streets on Thursday as a massive wall of water threatened to unleash near record flooding all the way to the Gulf of Mexico.

Water lapped over Riverside Drive and onto Beale Street in Memphis, and threatened some homes on Mud Island, a community of about 5,000 residents with a river theme park. The island connects to downtown Memphis by a bridge and causeway.

Emergency officials in Millington near Memphis were "going door-to-door, asking people to leave," according to the Tennessee Emergency Management Agency.

Large amounts of rain and melt from the winter snow has caused a chain reaction of flooding from Canada and the Dakotas through Illinois, Indiana, Missouri, Kentucky, Arkansas and Tennessee. It is expected to soon hit Mississippi and Louisiana at the mouth of the Mississippi River.

"The flood is rolling down, it is breaking records as it moves down and it is one of those wait-and-see type of things as to how massive it is going to be when it's all said and done," said Charles Camillo, historian for the Mississippi River Commission and the Mississippi River and Tributaries Project.

In Arkansas, westbound traffic on a section of one of the nation's major trucking arteries, Interstate 40, was closed for a second day due to flooding.

The White River was expected to crest at its highest ever level of 40 feet at Des Arc, Arkansas on Thursday night, breaking a 1949 record.

A levee overflowed near the White River, forcing a mandatory evacuation of the town of Cotton Plant, the Arkansas Department of Emergency Management said.

Officials at the Shelby County Office of Preparedness, that includes Memphis, predicted that the flood could affect 2,832 properties if it crests at 48 feet this coming weekend.

A crest of 48 feet would be the river's highest level since 1937, according to the National Weather Service. The service currently puts the river level at Memphis at 45.21 feet, with an expected rise to 47.6 feet by Monday morning.

The flooding is also affecting towns not directly on the Mississippi. Residents in south Dyersburg, Tenn., about 20 miles from the Mississippi, have been asked to evacuate because of the projected crest of the North Fork of the Forked Deer River, which runs into the big river.

North of Memphis upstream, the U.S. Army Corps of Engineers blew up a third section of a Missouri levee Thursday afternoon to let flood waters back into the Mississippi.

The Corps blew up a two-mile section of the Birds Point levee Monday night to help ease flooding in Illinois and Kentucky. The levee destruction resulted in the flooding of 130,000 acres of Missouri farmland. The Corps then blew up two smaller sections of the levee Tuesday and Thursday to let water back in the river.

President Barack Obama on Wednesday declared parts of Kentucky, Mississippi and Tennessee as disaster areas due to flooding. Missouri Governor Jay Nixon Thursday requested that Obama make a major disaster declaration for the state as a result of high winds, tornadoes and flooding since April 19.

The levee system in Mississippi is holding for now but it has never been tested like this before, officials said.

"Compared to the Great Mississippi Flood of 1927 this flood is going to be a lot nastier," said Marty Pope, senior hydrologist for the National Weather Service in Jackson, Miss.

The river is predicted to crest at 64.5 feet on May 17 in the Vicksburg, Miss. area. Vicksburg has a flood stage of 48 feet, which means the river will crest more than 16 feet above normal, according to flood experts at the National Weather Service.

The flood waters will reach more than a foot above the Yazoo Backwater Levee near Yazoo City, Miss. and this will flood thousands of acres of farmland, said Pope.

There were major floods on the Mississippi in 1927, 1937, 1973, 1993 and 2008. The 1927 flood caused up to 1,000 deaths and left 600,000 homeless. Floodways were adopted as a response.

Camillo said it was too early to estimate expected damage from the 2011 flooding. He noted that much has changed since the 1927 flood, including the structure of the levees and the addition of dozens of reservoirs throughout the Mississippi River basin and floodways.

The Mississippi has four floodways: Birds Point and three spillways in Louisiana.

"There is a very good possibility that we would operate three floodways ... and we have never done that before," Camillo said.

(Additional reporting by David Bailey in Minneapolis, Tim Ghianni in Nashville, Suzi Parker in Little Rock and Leigh Coleman in Biloxi, Mississippi; Writing by Mary Wisniewski; Editing by Greg McCune)

NEW YORK (Reuters) – Names of all 2,982 people who died in the September 11 attacks will be grouped as friends, work buddies and families on bronze panels at a national memorial opening in New York, organizers announced.

Rather than an alphabetical listing or purely random collection, the names will be arranged in what organizers described as "meaningful adjacencies" at the National September 11 Memorial & Museum.

"They died as friends and co-workers and will be remembered together as friends and co-workers," Joe Daniels, the president of the memorial, said in a statement on Thursday.

"They died as brothers and will be remembered as brothers -- or as sisters, mothers, fathers, sons, and daughters. The arrangement of the names, forever etched in bronze, expresses the bonds that could not be broken by the murderous attacks of that day," Daniels said.

Tickets to enter the memorial, which are free, can be reserved online starting this summer. The site opens to families of the victims on the tenth anniversary of the attacks and to the general public on September 12.

Arranging names by relationships "helped us infuse the memorial with meaning and depth," said memorial architect Michael Arad.

The grouping was based in part on more than 1,200 requests made by victims' families. An electronic guide to the location of each name is available now on the memorial's website -- 911memorial.org -- and soon as a smartphone app. The guide also includes brief biographical information and, in many cases, photographs of each victim.

The memorial is being built in lower Manhattan in the two footprints of the twin towers, which collapsed after being struck by hijacked planes. Each will become a large square pool fed by waterfalls and surrounded by the panels bearing the victims' names.

The memorial will commemorate all those who died in the 2001 attacks, including first responders and building occupants at the Pentagon and the World Trade Center as well as the passengers and crew of all four hijacked planes, one of which crashed in a Pennsylvania field.

It also honors the victims of the 1993 bombing of the World Trade Center.

The memorial and nearby museum will be the first areas of Ground Zero to reopen to the public in the decade since the attack. Construction continues on the skyscrapers that will replace the fallen twin towers.

President Barack Obama visited the site on Thursday to mark the success of a military operation last weekend in which Osama bin Laden, the mastermind of the attacks, was killed.

(Editing Barbara Goldberg and Jerry Norton)