Mitchell Int'l Moves Explosives Detection Behind the Scenes

The ticketing lobby at Milwaukee's General Mitchell International Airport (MKE) is once again more open and spacious. Gone are the seven SUV-sized explosives detection system machines that invaded the entry space after 9/11 changed screening requirements. And travelers no longer have to maneuver their luggage to the large, intimidating machines.  

The old bulky screening equipment has been replaced with a new baggage system with inline screening. Four new L-3 explosives detection machines now do their work in a new 24,000-square-foot building located on the secure side of the airport, out of customers' sight. 

The $28 million project was completed last June, $4 million under budget.

MKE got the ball rolling on its complex, time-consuming initiative with the completion of a separate project several years before. "Prior to 2006, we had eight walled off areas in the baggage makeup area," explains Milwaukee County Project Manager Tim Kipp. "Each airline in the garage-like area did their own thing: putting bags on a belt, then on a cart to be transported to the aircraft. For years, airport administration tried to secure TSA money to move the L-3s out of the ticket lobby, but at that point there was little or no funding available for medium-hub airports."

With no quick solutions in sight, MKE airlines prepared for the time funding would become available and renovated the backroom space to accommodate an inline system at a cost of approximately $8.5 million. Work crews tore down the walls separating the spaces to create two common-use rooms, each with two baggage carousels. During the two-year project, each airline took its turn temporarily running baggage makeup operations out of a large tent. After each airline's area of the building was completed, personnel moved back inside the newly renovated space. 

The first phase was definitely the most disruptive for carriers, Kipp recalls. "We had to put airlines into the tent in the middle of the winter," he details. "We even had to move their operations offices out of the building into trailers ... We knew that eventually we would get the money to construct a new baggage handling system; we just didn't know when. But at least the preparatory work would be done when the funding did become available."

Patience Pays Off

In August 2010, the airport finally entered into a transactional agreement with TSA to construct an inline baggage system. Under the agreement terms, TSA would fund $21 million of the $28 million project and passenger facility charges would pay for the remaining $7 million. 

With funding in place, the airport hired GRAEF to lead the design team and manage the project. American Design and Build, in turn, managed the construction portion, which required a non-traditional approach. "The design approval was dragging out, so we initiated work on the infrastructure for the new building," informs Chris Schmidt, the firm's project manager. "Existing airport functions were relocated, the sheriff's checkpoint to access the secure airside was moved, a new security gate was installed and some fuel hydrant work was performed. We also reconfigured the loading dock area to accommodate the new addition. So when TSA signed off on the plans, we were ready to go."

GRAEF Vice President Lori Rosenthal explains the reason behind the delay: "We were all trying to come to terms with what the correct capacity numbers should be by looking at current capacity needs in relation to projected needs."

The final design settled on four L-3 machines, each with a capacity of 750 bags per hour - plenty to handle the airport's current peak need of approximately 1,500 bags per hour. The airport regularly uses three machines; the other one serves as a backup. The new system provides MKE with approximately the same capacity as the previous seven machines that resided in the ticketing lobby, notes Kipp. 

Today, when travelers check in, staff place their bags on a conveyor belt behind the ticket counter. The bags are then transported for screening to the new matrix on the secure side of the airport. Bags requiring manual screening are hand checked in the Checked Bag Resolution Area, where TSA personnel use a hand-operated suction machine, which transfers bags from the suspect line to the cleared line.

The most measurable and significant result of the new baggage handling system is lower labor costs. Fewer TSA personnel are needed to screen bags, and those on duty experience fewer injuries. 

"Under the old system, everything was done by hand," Kipp explains. "Each of the seven machines in the lobby was staffed by up to four TSA employees. It was labor-intensive, with a higher risk of back injuries. The new system streamlines the baggage screening operations, which allows TSA to reduce staff. From the TSA's perspective, that was a major driver to get this project done."

Infrastructure Challenges

An early conceptual design for MKE's new checked baggage system took a two-building/two matrix approach - one set at the north end of the terminal and another at the south end - with a total of six medium-volume explosives detection machines. The two-building design was originally considered because a single-building design required bags to travel by an elevated conveyor from ticket counters on the far south end of the terminal to a new building on the north end for screening, then back again to the south end to the baggage makeup carousels. The obstacle to that approach was a 60-inch deep, 50-foot span plate girder stretching east and west near the center of the terminal. The girder supported a significant portion of the connector bridge to Concourse D, including the floor, roof, precast walls and over 20 beams. It also blocked the way of the proposed conveyor route. 

To make a single-building design work, 2 feet of girder depth needed to be removed to allow conveyor passage and the 8-foot clearance needed for baggage tugs below. System designers resolved this problem by placing a 2-inch by 20-inch by 20-foot long bottom flange welded to the girder to allow for removal of the bottom 2 feet of the girder.

"The girder is a major beam. It probably supports 240,000 pounds," explains Rosenthal. "We shored it up, made the cuts and reinforced it. We made it work. Without that modification, the single-building strategy would not have worked."

The modifications also saved millions of dollars in construction costs and ongoing operational and maintenance expenses, she adds. 

Kipp recalls the break-though moment clearly: "Everyone was thinking that it would be too difficult to go around the beam. Then GRAEF assured us that we could cut through the beam and keep the structure upright. That helped tremendously. At that point, we could further help TSA reduce staffing needs by concentrating its workforce in one building instead of two."

The new baggage handling system/inspection matrix building was sized to be constructed over the tug passage next to the existing bag makeup building and over the basement tug tunnel access ramp. The narrow tug passage and ramp allow just enough room for two-way tug traffic. The addition of new building columns would have restricted tug passage to one-way traffic.

Pressure-meter soil testing not available when the terminal was built in the 1980s determined that the soil could support 5,000 pounds per square foot with the existing footings, as opposed to the 2,000-pounds-per-square-foot determination in the original design. Crews also analyzed the existing tug ramp retaining walls and footings for baggage handling system column loads. The new soil capacity figure was found adequate as long as column spacing was kept close to reduce local loads on the wall. The tug passage clearances were maintained, saving several hundred thousand dollars in foundation work.

Construction Challenges

Proper phasing and schedule coordination was a major focus to ensure ongoing airport and airline operations during the project. Primary stakeholders met weekly for phasing and construction activity updates.

During the first "make-ready" phase, crews relocated a portion of the airport's underground fueling system to allow for setbacks on the new building. They also added a new electrical duct package to serve the loading dock area. The duct had to cross the road that serves the loading area and pass through each of the respective loading dock positions, which affected daily airport deliveries. A new airside checkpoint was established while workers removed the existing checkpoint within the new building's footprint.

Phase two included construction of the new baggage handling system building, with planners sequencing work to allow for airline vehicle and pedestrian traffic. Because the new building was located on the secure side of the airport, workers had to be badged and pass through security to be allowed onsite. Contractors also had to have material deliveries inspected; secure tools, materials and equipment at all times; and keep construction debris within a defined area.

Baggage handling conveyors and in-line screening equipment were installed during phase three. MKE retained existing ticket counter conveyors and carousels at the passenger pickup locations for use with the new system to reduce costs. 

New conveyors and screening equipment needed to be installed while bags continued to move through the system. To accomplish this, planners divided demolition of the existing baggage handling system and installation of the new system into 20 detailed sub-phases. An intricate schedule allowed design and construction teams to work around airline operations to connect each of the four ticket counter lines to the new single-line system.

"Communication was key to this project's success," emphasizes Schmidt. "We made a concentrated effort to keep everyone informed about what was going on. We met with the stakeholders on a daily basis and held weekly meetings where we discussed what work was taking place and what work was coming up. Getting all of the stakeholders buy-in every step of the way really streamlined the construction process."

Personnel from VTC, the GRAEF subcontractor that designed the baggage handling system, enthusiastically agree. "The success of this project had everything to do with the great communication and coordination between TSA, the airport, the design team and the contractors," says VTC Project Manager Jeff Callaghan. "It's truly one of the best projects we have been part of."

Up & Running

Before MKE's new system went online last June, it underwent three months of testing. Airport and design personnel agree that the testing process is one of the toughest components of adding a new baggage handling system. 

After construction was complete, the project team conducted an initial test of the system, and then the design team tested it and signed off. In addition, TSA brought in Raytheon to conduct independent testing. After Raytheon signed off, Battelle tested and certified the system for use by TSA.

VTC Chief Executive Officer Chris Norton explains the long process: "During preliminary testing, we worked with Jervis B. Webb to try to break the system, so that by the time Raytheon and Battelle show up, testing runs pretty smoothly. We have a testing facility and we are very good at finding the limits of a system. By the time we finish, we are confident that it will stand up to Raytheon and Battelle."

With bulky explosives detection machines tucked behind the scenes, the ticket lobby is now more spacious and better facilitates passenger flow, reports Kipp. Airlines have added kiosks in front of the ticket counters, and the space available for leasing has increased.

"This is the latest in a series of investments we are making in Mitchell Airport to ensure that we provide the best possible experience for passengers," states Milwaukee County Executive Chris Abele proudly. 

Personnel from Jervis B. Webb, the firm that manufactured and supplied the conveyor system, characterize MKE's new baggage screening and handling method as a very clean system. "I've been doing this since 2001, and this is probably the best closeout on a project I've ever experienced," reflects Senior Project Manager Bernie MacDonald. "I can say with sincerity that they are great people in Milwaukee."