Stations are large, especially with pedestrian bridges for access. Straddle bents (the beams spanning the street) are used when there's not space for columns.
See my previous 6/23/07 post Wilshire Monorail? on this subject, also Flood channel monorails?
For more on monorails (see also Wilshire monorail?), David Lazarus' 12/9/07 column "Southland transit is in need of big ideas" suggested:
Brian C. Brooks, an L.A. County Department of Public Works employee, believes he has the answer, which he shared with me after laying out a map of the county's system of flood channels.
"If you had a monorail system all over Los Angeles, along all the flood channels, it would be like having a magic carpet, carrying you above all the traffic," he said. "Absolutely this would work." ...
Brooks believes a monorail network can be built along L.A.'s flood channels for less than $35 million per mile, or a tenth the estimated cost of expanding the existing subway system. A 10-mile monorail line could be up and running in less than three years, he said.
"Californians are an above-ground people," Brooks said. "We don't want to be underground in a dark tunnel. We want to be above it all, in the light."
This image shows how a flood channel monorail could look, north from the Charnock Ave. bridge in Mar Vista, between McLaughlin and Sawtelle (enlarge).
I was a regular San Francisco Bay Area BART rider in the 1970s, and every time the train came out of the subway onto elevated track I enjoyed seeing daylight (or even night). So I'm another who prefers to ride above ground.
Monorails have operated in transit service in a number of cities around the world, and certainly have a cool factor from Disneyland, Disney World, etc. -- even if the Disneyland monorail only bumped across the parking lot at 25 mph.
But I'm concerned monorails are oversold, especially when a company claims costs and performance that it has never built. Here are three issues about monorails along flood channels: 1. Would they fit? 2. How much would they cost? 3. Would they go where people travel?
1. Fit. Running along storm channels raises issues of space for 5-6-foot wide columns and noise and visual impacts for neighbors, commonly single-family residential neighborhoods. I rather doubt that the owners of the houses on the right would welcome this past their back yards; some of the most heated opponents of the late Orange County CenterLine were Irvine homeowners along the flood channel where it would have been built.
The Las Vegas monorail (train used in image) is a close comparable to the unbuilt Metrail proposal Brooks cites. Las Vegas' Bombardier trains are about the same size but not as tall, also made of lightweight composite materials. The standard Las Vegas columns are 4'-8" x 2'-8" and 18+ feet tall. In Los Angeles they would likely be thicker to for our seismic standards; the L.A. Green Line's columns are about 6 feet in diameter.
Las Vegas trains are relatively quiet, but could not be called silent, with tire noise and a metallic whoosh as they pass. Metrail proposes to add an on-board engine instead of electric power, which would add to its noise, likely making it sound like a Long Beach diesel hybrid bus.
2. Cost. It's very unlikely a Metrail monorail could be built for one-tenth the cost of subway. The Las Vegas monorail was built between 2001 and 2004 for $100M per mile (source) by an experienced engineering company (see construction photos by The Monorail Society).
With Brooks's Metrail trains about the same size and weight as Las Vegas' its guideway and stations would be quite similar, while costs have inflated seriously since then. Best case is probably $100-150M per mile, at least 1/3 the cost of subway.
3. Usefulness. Finally, would monorails along flood channels put stations in places useful for travellers? In many cases, no.
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.)
