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5.4. BRIDGE DECK

The bridge deck is made of 776 precast concrete sections that are elevated 20 feet (6.1 m)
above the concrete pontoons that forms the lower deck which essentially creates "a bridge

on top of a bridge". Unlike the older bridge, maintenance vehicles can now access the

pontoons from beneath the upper roadway deck without interrupting traffic. According to
a project engineer on the site, the deck had to be structurally isolated from the main support

structure using a damping system to ensure seismic resistance up to a magnitude 9
earthquake to comply with local building codes. The original deck design called for three

support columns but was later revised to two due to aesthetic issues. Moreover, the lighting
mounted on top of the deck had to be positioned to minimize light pollution as well as its

effect on aquatic habitat.

5.5. LAYOUT

The bridge has two general purpose lanes and one high-occupancy vehicle lane (HOV
lane) per direction. It includes shoulders and a 14-foot-wide (4.3 m) pedestrian/bicycle

path on the north side, unlike the 1963 bridge. Congestion on the old bridge was blamed

on lack of shoulders, where disabled vehicles would cause severe backups. Ornamental
elements include four sentinel towers rising 43 feet (13 m) above the bridge deck at the

approaches, and belvederes on the north side.

5.6. PUBLIC TRANSPORTATION

Public transportation and high-occupancy vehicle (HOV) use were incorporated in the

bridge design. The bridge includes HOV lanes with priority for transit. A 2008 WSDOT
report included five core bus rapid transit routes proposed by Sound Transit connecting

the Eastside (Kirkland, Redmond, and Bellevue) to Downtown Seattle and the University
District, with a base frequency of 15 minutes, increasing up to 7 minutes at peak times.

Existing freeway bus stations (also known as "flyer stops") on the Eastside at Evergreen
Point and Yarrow Point were rebuilt and moved from the freeway's shoulder to the median,

accompanied by landscaped lids with parking and lawns, in 2014 for increased

compatibility with the bridge's planned HOV lanes.

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