Wilshire Monorail?

A monorail along Wilshire Boulevard has been suggested as a faster and cheaper alternative to extending the Purple Line "Subway to the Sea". Here are some considerations to evaluate whether a monorail could fit.

This image of the Las Vegas Monorail superimposed onto Wilshire in West Los Angeles shows the visual bulk of its concrete beams and columns, and how it blocks the left turn lane.

Las Vegas has the only transit monorail in the United States, begun construction in 2001 and opened in 2004. Its 2000 construction cost was $100 million/mile ($385 million for 3.8 miles; source). This was similar to elevated light rail, and about one-third the cost of subway construction. It would be more now, with construction cost inflation.

Las Vegas uses a proprietary Bombardier (Canada) design based on Walt Disney World. Hitachi (Japan), the world's other main monorail vendor, uses a different, incompatible, design. It's risky to be dependent on a single vendor.

Spans for the Las Vegas beams average 100 feet, with the longest about 120 feet. They are 26 inches wide and vary from 5 to 7 feet deep. The typical column is 56 inches by 32 inches (source). They likely would be larger in Los Angeles to meet our seismic requirements.

Aerial stations are quite large, cantilevered over the street with pedestrian bridges to the sidewalk, needing space for stairs, handicapped-accessible elevators, and possibly escalators (which tend to break in the weather). Is this acceptable on Wilshire?

Passengers would experience a 10-15 minute delay at Western Avenue, to transfer between aerial and subway stations and wait for another train.

What are alternatives to losing the left turn lane to columns? Las Vegas' 120-foot maximum span is far short of this typical boulevard intersection at Wilshire and Bundy, where it would take a 550 foot span across the left-turn lanes and cross street.

Even this massive bridge of the Green Line over Aviation and Rosecrans in the South Bay is only just over 300 feet.

The other possibility is "straddle bents" spanning the entire boulevard, like these three supporting a curve in Las Vegas. These would also be used if the beam curved to the edge of the boulevard if stations were built in buildings' upper floors.

For more perspectives see The Monorail Society and Light Rail Now.

(I plan a future post about monorails along freeways.)