Hospital Pedestrian Overpass Poses Logistical and Safety Challenges

The elevated pedestrian walkway at the BJC Healthcare/Washington University Medical Center complex connects the parking garages to buildings in the medical campus. It is approximately 1,200 feet long. Photo Paric Corporation and KAI Design & Build.

“The more complicated and complex the project, the more it is up our alley,” says Drew Bade, project manager for Bade Roofing Company in St. Louis, Missouri.

The company’s recent work roofing the new 1,200-foot-long elevated pedestrian walkway at the BJC Healthcare/Washington University Medical Center complex in St. Louis certainly qualifies as complex. The fully enclosed walkway connects the parking garages to buildings in the medical campus. Constructed atop 14 concrete pillars at an elevation of approximately 40 feet over busy roadways, the 13-foot-wide structure posed obvious logistical and safety challenges.

Bade Roofing’s union-affiliated workforce focuses on commercial projects, and the lion’s share of the company’s work is in the re-roofing arena. But for this new construction project, designed and executed through a joint venture between KAI Design & Build and Paric Corporation as part of a long-term project to update the medical campus, Drew Bade knew his company was the right candidate for the roofing portion of the job. The successful roofing installation proved him right. “We teamed up with Paric and KAI and made this thing happen,” says Bade.

The Roof System

The heated and air-conditioned walkway features carpeting, LED lighting, security intercoms, windows and metal wall panels. It also features a durable roof system. “It’s a walkway, but this thing was built like a tank,” notes Bade.

The walkway was constructed atop 14 concrete piers that elevate it over busy roadways. Photo Paric Corporation and KAI Design & Build.

The roof is a Firestone TPO system that includes R-20 polyiso insulation and a half-inch DensDeck cover board from Georgia-Pacific. The 60-mil UltraPly TPO membrane was attached using Firestone’s InvisiWeld induction welding system. The base of the system is the walkway’s 18-gauge steel deck, which features interior drains, scuppers and downspouts. Tapered insulation was used to provide proper drainage.

To make the project’s logistics even more complicated, work was scheduled on the fly as different areas of the walkway were completed. “There were some areas that weren’t built yet when we started to put this roof on,” Bade recalls. “It was a fluid situation. It was a challenge just to keep up with the changes, and we had to bounce around a lot. We couldn’t just start at one end and roof our way over to the other end. We had to hop around and handle what was finished at the time, tying the sections in together as they were completed.”

The short parapet walls were capped with edge metal after the roof was installed. “In some spots, after the roof was put on, it was more like a drip edge than a parapet,” Bade says. “At the highest, it was about 8 inches. We installed edge metal that tied into the metal wall panels they used on the sides of the bridge. It was all integrated together.”

Loading components proved tricky. “Getting material to each section and moving it around was a challenge in itself,” Bade explains. “We had to coordinate certain time frames that we could get our crane into an area to drop the material off. Because of how the safety systems were set up and how narrow this bridge was, you couldn’t really transport material along it very far. The crane essentially had to put the material right where it was going to go for that day.”

Loading the roof was usually done first thing in the morning, as use of the crane could mean blocking off roads or going into gated areas. “We’d try to beat all of the other trades in there,” Bade says.

The Safety Plan

The key to executing the project was finding the right safety plan. Initially the team explored the use of a

The Beamguard lifeline system from Guardian Fall Protection was installed in the center of the roof deck by workers in a boom lift. Photo Bade Roofing Company.

temporary guardrail system, but it proved infeasible due to the short parapet walls. “We use temporary guardrails on almost 100 percent of our projects, but the engineer came back and said the parapet walls weren’t strong enough to support a guardrail system,” Bade recalls.

The company looked for other options. “We looked at a special system that is more commonly used on road bridges during construction,” he says. “It uses a cable that runs between stanchions, and crew members can clip off to the cable.”

The system chosen was the Beamguard lifeline stanchion system from Guardian Fall Protection. The posts were attached to the steel I-beams every 30 feet. “We had to cut the metal deck out and clamp the posts to the I-beams,” Bade explains.

Crew members’ personal fall arrest systems were connected to the lifeline, but only two workers could tie off to the cable in between the stanchions. “We were tied off 100 percent of the time,” Bade says. “Safety was a huge issue for everyone on this project. There were no warnings. Everyone knew that if someone wasn’t tied off, they’d immediately be thrown off the job.”

The stanchions for the lifeline system were attached to the steel I-beams under the roof deck. Photo Bade Roofing Company.

The cable system posed some limitations on crew movement, which affected the delivery of materials. “With the cable system, you could only go so far because only two people could be tied off to a 30-foot section at a time. Essentially you had two guys walking 30 feet to hand insulation boards to the next two guys. It was kind of like a chain gang, moving material down each section of the roof.”

Ensuring the safety of pedestrians and vehicles below was also crucial. “There was a sidewalk area in the parking garage that was fully functional during the project, as there was a walkway constructed of scaffolding that offered overhead protection,” Bade notes.

However, other areas of sidewalk and roads had to be closed in order to complete work on some sections. “It depended where you were working that day,” Bade says. “Some areas of sidewalk had to be closed, and sometimes we had to redirect traffic. If you were working in areas without scaffolding, you would have to have two guys on the ground with flag lines directing traffic and blocking people off.”

One crucial section over a busy road posed some additional challenges. The three-lane road could only be shut down on one weekend. All of the trades had to complete their work that weekend, so the roofing installation had to be completed in just one day. “We did a 120-foot stretch of the roof that crossed this main road, and we did it all on a Saturday. It was the only opportunity we had. Otherwise we would’ve had to pay to shut the road down lane-by-lane, as we went. We were lucky that we were able to get in there on that one day and finish the whole length.”

The roofing installation was completed in sections as they were constructed after the 18-gauge steel deck was in place. Photo Bade Roofing Company.

Communication between all of the companies involved in the project was essential, notes Bade. “The foremen for every trade met every morning before work started. All of the contractors on the project had their meeting every week to plan and go over everything,” he says. “There were multiple forms you had to fill out every morning. The paperwork on this project was flying like you wouldn’t believe.”

After the work was completed in each section, the safety system had to be disassembled and removed. The last chore completed on each portion of the roof was to fill in the patches of roofing material where the stanchions had been. Workers completed these last steps tied off to a snorkel lift.

Despite the logistical hurdles, the project went smoothly and feedback has been positive, notes Bade. “It ended up being a great project for us,” he says. “It turned out really nice.”

It’s just another tough project now in the rear-view mirror. “The coordination, the safety, and the complexity of the actual roof system itself — not that it was necessarily a difficult roof to install, but given where it was, and how difficult it was to access — it all shows how dedicated and skilled our company is,” Bade concludes. “I don’t think there are a lot of companies out there that could do this project.”

TEAM

Architect: KAI Design & Build, St. Louis, www.kai-db.com
General Contractor: Joint venture between KAI Design & Build and Paric Corporation, St. Louis, www.paric.com
Roofing Contractor: Bade Roofing Company, St. Louis, www.baderoofing.com

MATERIALS

Membrane: 60-mil UltraPly TPO, Firestone Building Products, www.firestonebpco.com
Cover Board: DensDeck, Georgia-Pacific, www.densdeck.com