he terrorism of September 11 may be felt more strongly at Boston Logan International Airport than at any other airport. It was there where the two aircraft used to destroy the World Trade Center towers departed that morning, which may explain why New England's main airport has been a major site for studying new security strategies and technologies.

The effort began shortly after September 11 with tests of biometric facial recognition technology at passenger checkpoints, an experiment test that didn't work out but one that demonstrated the Massachusetts Port Authority's willingness to try new things in aviation security.

That atmosphere of experimentation has been extended to cargo, making Logan the focus of tests on new air freight security initiatives that are being watched closely by air carriers and other operators.

Most airports on the U.S. East Coast have focused their cargo security efforts on controlling access to sensitive freight loading areas, and defer to the Transportation Security Administration on technology initiatives. But Logan decided to conduct its own cargo screening trials.

"We wanted to develop real world data that we can give to the TSA," says Massport spokesman Jose Jueves. "We're trying to take a big picture view here. Everybody is talking about cargo screening. Let's get some data and really study the issue."

Logan is the site of an ongoing pilot program for electronically screening freight being loaded onto aircraft, particularly belly cargo going on passenger planes.

Boston is the first major U.S. airport to electronically scan bulk cargo in an effort to determine how realistic comprehensive cargo screening would be, and exactly how it would be done.

The results so far are unclear, and implementing the program on a wide scale and permanent basis would likely be too costly for Massport to fund itself.

But the program, in which New York-based L-3 Communications X-rays the contents of selected trucks offloading cargo, may be an early indication of the way in which air freight would be electronically inspected if the sort of strictures that govern passenger luggage are extended to air freight shipments.

For airports, particularly those on the densely-populated East Coast, the tests are especially important as they try to figure out not only how to pay for new cargo security standards but how to fit screening into the tight spaces that hem in many airport cargo facilities.

Most carriers and many airport operators believe the physical scanning of all or even most air cargo would be unworkable and debilitate an industry built on the rapid movement of time-definite goods. "The last thing airports need is a situation where technology is slowing things down," said L-3 Security and Detection Systems President Joe Paresi.

U.S. airports are generally reluctant to talk about cargo security, saying the TSA has cautioned them not to reveal details about security initiatives.

ut major East Coast airport operators do note that they've spent large amounts of money on security since September 11, and appear reluctant to invest in the kind of technology in the Logan experiment.

The Port Authority of New York and New Jersey, for example, has spent $300 million since September 11 to enhance security at Liberty Newark International and New York's Kennedy and LaGuardia airports. The Port Authority plans to spend an additional $500 million over the next five years.

Port Authority spokesman Tony Ciavolella says much of the money has gone towards restricting access to secure areas and buttressing the perimeters of these areas by installing sophisticated surveillance equipment. The Port Authority has also invested in bomb-sniffing canine teams and dispatched them in both passenger baggage and cargo loading areas.

Even as they have doled out money to enhance security, U.S. airports have argued that aviation security falls under the banner of national security and should be paid for by the federal government. The TSA has covered billions of dollars worth of airport security costs, and likely would have to foot the bill for any electronic cargo screening equipment it required airports to install.

"The $10 million question [regarding electronic cargo screening] is who will be responsible for paying the costs," said J. Michael Webber, a consultant and former director of cargo affairs at Airports Council International-North America. "Airports have already absorbed a tremendous burden of airport security costs. Any new requirements heaped upon an already critical financial situation would have airports dipping into their reserves."

U.S. airports operate under comprehensive security plans, approved by the TSA, which include cargo. The primary cargo security role played by airports is ensuring that cargo areas remain difficult to penetrate. This involves both securing airport perimeters and vetting those with access to cargo loading areas.

irports want to avoid situations like one at cargo stronghold Miami International Airport, where a foreign national working as a cargo handler was discovered to have obtained his security badge "under false pretenses." The man pleaded guilty in U.S. District Court in Miami and was deported in 2002.

The U.S. Department of Justice's post-September 11 "Operation Tarmac" nabbed hundreds of illegal immigrants working at airports, including cargo handlers, who had used false U.S. Social Security numbers, birth certificates and identifications to obtain badges giving them access to secure areas of major airports. The DOJ said none of those arrested in the national sweep had known connections to terrorist groups, but cautioned that the employees' status as low-wage illegal workers made them prime targets for recruitment and manipulation.

The TSA's recent air cargo strategic plan calls for airport operators to make greater use of criminal history records checks and "employ additional measures" for identifying and screening people with access to cargo loading areas and aircraft.

At Washington Dulles International Airport, those requiring access to sensitive cargo areas are fingerprinted; the prints are then sent by the Washington Metropolitan Airport Authority to the Federal Bureau of Investigation to be cross-referenced with the FBI's criminal database. This practice is becoming increasingly common at U.S. airports.

Outside of Logan, however, airports have not experimented with electronic scanning.

"Everybody agrees increased investment in [cargo screening] technology is a good idea, but they're skeptical about how soon the technology can arrive," says Webber. "The TSA is moving judiciously. The technology is not there to screen 100 percent of cargo efficiently."

The Logan experiment is being done with L-3's CX-450M mobile cargo X-ray inspection system, which has been used previously to scan trucks at border crossings. The high-tech truck is equipped with an upside-down L-shaped X-ray arm that can pass over and scan the contents of cargo truck trailers. Inside the CX-450M is a control room, where an L-3 inspector views the images being scanned inside the truck's trailer and looks for stowaways, explosive devices, weapons, drugs and other contraband.

A truck being scanned is stationary while the CX-450M moves slowly back and forth beside it and immediately displays an image of its contents, as well as the contents of the pallets inside the truck, according to L-3.

"It produces a pretty clear picture," says L-3's Paresi. "This stuff works in terms of finding these kinds of hidden objects. This is just a new application of an existing technology that has been used successfully for years for customs purposes."

Neither L-3 nor Logan will say how many trucks are scanned per day. And Paresi says he is "not aware of anything at Logan that has been found" by the scans.

Logan's Jueves says the number of cargo trucks screened daily "varies," but he claims "several air carriers were very interested and volunteered to participate in the program."

He adds that the open-ended pilot program is designed to determine "what are the [electronic screening] conditions that would put a burden on cargo operations."

Paresi says there have been no complaints from airlines about cargo throughput being slowed by the scanning. "That has not been an issue at all," he said.

"You're talking about scanning an 18-wheeler in a minute."

The Logan pilot program has been in operation since October, but a comprehensive analysis of data has not been completed.

"This is a good opportunity for both parties [L-3 and Logan] to experiment and try to figure things out," said Paresi. "We have to sit down with the people at Logan and figure out what we've learned and where we're going with this."

Paresi says L-3 also has smaller stationary X-ray machines designed to scan cargo pallets after they've come off trucks, and is interested in testing these at airports.

He estimates that a major airport implementing a wide-scale electronic cargo-screening program would likely need one CX-450M unit, which costs $2 million, and five to seven stationary pallet scanners, which cost $700,000 each. That would bring the total cost of deployment, not counting personnel and maintenance, to $5 million to $7 million per airport.