Aerial Innovations Of TN, Inc.
When air ambulances take off from or land at adjacent helipad (below), crane operations shut down for up to 20 minutes, reducing crane efficiency by 13%.
Every 15 to 20 minutes at the site of a 328,779-sq-ft addition-renovation for Vanderbilt University Medical Center, the hum of the tower crane engine is replaced by the “hum” of a helicopter taking off from or landing on the roof of the neighboring operating hospital, just 102 ft away from the crane. The silencing of the crane is the most noticeable work disruption at the 10-level infill project, hemmed in on three sides by the existing hospital and restricted below by a one-level emergency department. The contractors also have to share the street in front of the site with ambulances and public traffic. And they have to muffle noise and control dust because the $234-million Critical Care Tower development, 41% complete, is not only snug up against occupied patient rooms and active surgery suites, it invades the existing hospital so the two buildings will function as one.
“If you have a decision to make regarding how to do the work, you make it as though your wife, husband, child or parent was the patient we’re taking care of,” he says.
That might very well be the case. The hospital admitted more than 50,000 patients in the last year and treated more than 1.1 million adults and children as outpatients.
There is so much vehicular activity on the north-south shared-access street, named Medical Center Drive, that Vanderbilt and construction manager Balfour Beatty Construction performed a study of traffic patterns along the four-lane road to determine how to protect the public and keep vehicles moving. As a result, BB shut down three lanes of the road, keeping one open for ambulances and the public but covering it with a protective shed. The project uses a lane that goes through the site, under the shed. Ambulances also have parking bays under the new construction, west of the street, and three full-time police officers direct traffic, says Bobby Travis, project superintendent in the CM’s Nashville office.
Travis (left), Tenpenny (center), Bonds take care that construction doesn’t bother patients in neighboring hospital.
From a design standpoint, there were also “Quiet: hospital-zone” issues. “The new surgery floor extends into the existing one, so the biggest problem is controlling noise and vibration because of the proximity of mechanical floors to invasive surgeries,” says Tenpenny. The architect-of-record is Earl Swensson Associates Inc., working with mechanical-electrical-plumbing consultant Smith Seckman Reid Inc. and structural consultant Structural Design Group, all Nashville.
The impact of the constraints is exemplified in the project statistics. The $110.4-million infill addition is costing roughly $80 per sq ft more than a “greenfield” hospital and is taking four months longer to finish. The 284,503 sq ft of new construction, which began in December 2006 and is on schedule to be done in
the fall of 2009, and the 44,276-sq-ft renovation, set to finish in March 2010, are costing about $360 per sq ft, as opposed to $250 to $280 per sq ft, says BB.
The structural concrete frame has typical floors that measure 213 x 155 ft. The proximity to the two-copter helipad, which is heavily used because it also is a fuel depot, meant BB had to get Federal Aviation Administration approval for the crane operation before pulling the building permit.
Using a tower crane with a horizontal, hammerhead jib to lift formwork, precast concrete, structural steel and equipment was not possible. Instead, contractors are using a crane with a luffing boomn. “A conventional tower crane would have had to swing across the heliport,” says Travis. “No way that would work.”
The crane’s main operator, Tommy Craig of Concrete Form Erectors, Nashville, was handpicked by the hospital. Neil Ellis, Craig’s supervisor, also operates the crane and oversees crane set-up and dismantling. Tony McConnell splits the crane operation with Craig.
Some helicopters fly south, over the jobsite, on their way to a children’s hospital nearby. The crane operator, in constant radio contact with Vanderbilt Life Flight, is notified eight to 10 minutes before a take-off or landing. Then, he swings the crane around and shuts down until a notice to resume. The shutdown can last as long as 20 minutes.
The crane operator only needs to be in the cab during work hours, which are typically 6:30 a.m. to 11 p.m. weekdays. The crane operates on Saturdays for delivery of large equipment and occasionally on Sundays for things like installing the protective...