Wednesday, July 13, 2011

How many buses on Wilshire?

Another bit about Los Angeles: while there, we decided to take the bus on Wilshire towards Santa Monica. In doing so, we boarded one of the most frequent bus routes in the country. How frequent? At certain times of day, three dozen buses run along Wilshire Boulevard per hour, one every 100 seconds. They're split between the local 20 bus (headways of 6-12 minutes; 30 minutes overnight) and the Metro Rapid 720 bus (headways of 2-9 minutes, generally less than 5). Yes, two minutes. From 6:30 a.m. to 8:30 a.m. westbound, the 720 has an astounding 51 trips, with buses arriving every 2:20 on average (not counting the 20, which adds another 20 trips.

The 720 is operated with 60-foot buses which have a capacity of 100 passengers; or 2500 per hour, with an additional 600 capacity on the 40-foot 20 buses. 3100 passengers per hour—more than a freeway lane of traffic. Yet this parade of buses has operated in regular traffic lanes, with only limited abilities to hold traffic lights. That's slated to change, as rush-hour bus-only lanes have been approved for most of the corridor. The changes, which will cost $30m, are slated to save riders 10 minutes per trip. While it's not the ideal solution (that would be a decades-long plan to build a "Subway to the Sea" under the corridor, which would serve many more people and halve transit times), it is a relatively inexpensive fix which will help thousands of riders a day.

How "relatively inexpensive" is it? There are approximately 160 affected trips daily (buses don't run in each direction at the same frequencies), and we can assume that these trips are 75% full at rush hour (75 passengers per trip). That equals savings for 12,000 passengers per day, times 10 minutes, or 2000 hours saved per weekday, or 500,000 hours saved per year. There is limited literature regarding travel time costs (how much people value the time they spend in transit) but a conservative estimate is $8 per hour; about half of the prevailing average wage. (It's possible that mobile computing will raise this considerably.) In any case, 500,000 hours at $8 per hour is equal to $4m per year, giving the project an eight year payback in this metric alone.

Of course, LACMTA stands to save as well. Saving ten minutes per trip will save the agency 1600 minutes of bus operation per day, or about 27 hours. It costs about $100 to operate a bus per hour, equating to a savings of $2700 per day, or $675,000 per year (and these are much more quantifiable savings than the time costs).

Will bus lanes give Wilshire Boulevard an acceptable level of transit? No—with the ridership the corridor sees a grade-separated line is probably necessary. But since that is many years off, this is a step in the right direction.

No comments:

Post a Comment