So I spotted this piece on the LA Times blog site. Apparently it is the opinion of the LA Times metro staff that the 91 freeway through the Santa Ana River canyon is going to be improved by a new widening project. They're adding a lane in each direction.
Apparently nobody at OCTA has read the seminal 1998 UC Berkley study* that showed, using data from 30 years of California traffic, that adding lanes to freeways is a net loss in time- the time saved by the addition of new lanes will never add up to the time lost during the construction of those lanes, because of the phenomenon of "induced traffic." We can't pave our way out of traffic problems- it simply doesn't work.
If you want to relieve traffic on the 91 run through the canyon, here's a brilliant idea- give commuters a choice. Current transit service is limited to Metrolink, which is largely tailored to long-distance travelers, and is limited mainly to commute-hour service (the 91 Line, which parallels its namesake freeway, is among the most limited in the system, with no off-peak or reverse-peak service whatsoever), and two express bus lines- the OCTA 794, which just got disconnected from the rest of the bus system, and is peak-hour-peak-direction only, and the RTA 149, which is largely peak-hour only, at least on weekdays. (It's strangely more flexible on weekends.) Provide the thousands of daily 91 drivers with an honest choice of transportation options, with all-day, daily transit service through the canyon, via the 91 Express Lanes, and I bet you would see significant ridership and traffic relief. And it would be much cheaper than adding another lane to an already bloated freeway.
A quick primer on induced traffic and the paradox of freeway widening can be found here.
* Donald D.T. Chen. "If You Build It, They Will Come…Why We Can't Build Ourselves Out of Congestion." Surface Transportation Policy Project Progress VII.2 (March 1998): I, 4.