Half of it anyway.

A caravan of police and construction workers shepharded a 110-ton hunk of steel and copper at 5 a.m. to the hospital at Penn. The oversized load is half of a cyclotron, which accelerates sub-atomic particles to two-thirds the speed of light.

The second half of the device will arrive Wednesday. The cyclotron will weigh more than a Boeing 747-400 aircraft when it is put together.

When fully operational in July 2009, the equipment will be used to deliver ultra-precise beams of radiation to shrink patient tumors and minimize damage to surrounding tissue. The cyclotron will be the centerpiece of what Penn says will be the largest proton-beam therapy center in the world.

The load required a special 200-foot long truck with 20-axles to spread out the weight. It left the Packer Marine Terminal around 3:30 a.m. and took a circuitous route to University City in order to avoid driving over the Broad Street Line subway.

The caravan-with emergency lights flashing-entered Schuylkill Expressway and exited at University City.

Traveling at a top speed of 25 m.p.h. on the highway, the caravan slowed to snail's pace as it crossed the Gray's Ferry Bridge, and crept around street corners.

Two men, one in the front and another in the back, were required to steer the truck.

A giant crane was to move the weighty load at 8 a.m. onto the future site of the Roberts Proton Therapy Center at the Raymond and Ruth Perelman Center for Advanced Medicine, at 34th Street and Civic Center Boulevard in West Philadelphia.

The entire center, which is budgeted at $232 million, is the largest capital project undertaken by Penn Medicine, which comprises the Ivy League school's health system and medical school.

Penn will share the equipment with Children's Hospital of Philadelphia.

Staff writer Sam Wood contributed to this article.