Page 30 - COLLAGE

5.2. MAINTENANCE BUILDING

The bridge features advanced monitoring devices and new maintenance facilities. Beneath
the bridge is a three-story high brick building used to control and monitor various life

support and utility systems on the bridge. A backup generator sits on the ground level to

power all systems in case of power loss. Behind the back wall of the building lies a massive
retaining wall built in response to steep hills.

5.3. PONTOONS AND ANCHORS

The floating bridge is laid atop 77 concrete pontoons that float above the water and are
secured by 58 anchors to the lake bottom.

Of the pontoons, 21 are longitudinal pontoons that support the deck and structure and are
360 by 75 by 28 feet (109.7 m × 22.9 m × 8.5 m) and weigh 11,000 short tons (10,000 t) 54

smaller supplemental pontoons, weighing 2,500 short tons (2,300 t), are used to stabilize

the weight of the bridge; and two "cross" pontoons, weighing 10,100 short tons (9,200 t),
are sited at each end of the floating span at transitional spans, which connect the deck to

fixed bridges and approaches using hinges to move up to 24 inches (61 cm) for fluctuations
in lake water levels moving the pontoons. All the pontoons are designed with watertight

compartments that are monitored remotely with sensors to detect leaks that could lead to
catastrophic failure.

The bridge's 58 anchors all feature 3-inch-thick (7.6 cm), 1,000-foot-long
(300 m) steel cables and are divided into three types: 45 587-short-ton (533 t) fluke anchors

used in softer soils deep in the lakebed; eight 107-short-ton (97 t) gravity anchors used in

solid soils nearer to the shore; and five 10-foot-diameter (3.0 m), 79-to-92-foot-long (24
to 28 m) drilled shaft anchors used in conjunction with the gravity anchors to prevent

navigation hazards.

To ensure storm resistance in the event of water seeping into the pontoons, each pontoon

is outfitted with a leak detection system with a float switch that sits about 3 inches off the
floor. If the pontoon is breached, an alarm will sound inside the maintenance building.

From there, a pump can be lowered into the chamber and controlled from the deck above.

30