@article{ref1,
title="Tunnel keeps transit station environmentally sound",
journal="American city and county",
year="1999",
author="",
volume="114",
number="5",
pages="16-18",
abstract="Portland, Oregon's new Westside Metropolitan Area Express (MAX) adds 18 mi (29 km) to the region's existing light rail line, providing modern rail access from Gresham, east of the city, to Hillsboro on its west. The $963 million Westside extension includes a 3-mi (5-km) twin-bore tunnel under Washington Park, the busiest tourist attraction in the Portland area; one underground station; 19 surface stations; four multimodal transit centers; and nine park-and-ride lots. The twin-bore tunnel segment was selected over an aboveground alignment to preserve an environmentally sensitive canyon west of Portland. The 260-ft (79-m) deep tunnel had to be cut through three types of rock. At the western end of the tunnel, where rock conditions changed continuously, workers excavated via drill-and-blast, while a laser-guided tunnel-boring machine was used to cut through Columbia River basalt on the eastern end. The entire Westside line is equipped with low-floor train cars, making it the first system in the United States to use the European technology. All elements of the new Westside line are compatible with older Banfield segments, allowing the two lines to operate as a fully integrated system.<p />",
language="",
issn="0149-337X",
doi="",
url="http://dx.doi.org/"
}