Senator Boxer is fuming that Metrolink has just a single crew member in the cab on 87% of its runs.
The agency had said it would double up on crew members in locomotives as part of a series of safety reforms after the Chatsworth crash a year ago that killed 25 and injured 135. The so-called second-set-of-eyes plan was a hastily implemented reform after investigators found that the Metrolink engineer had been text messaging on a cellphone and apparently ran a red light just before crashing head-on into a freight train.
The Chatsworth collision is an example of what risk-expert Dr. John Adams terms “low-frequency, high-impact” incident. These types of incidents provoke knee-jerk reaction from politicians who feel the need to do something regardless of cost-benefit.
To my knowledge, there has never been a peer-review study on the benefits of two train drivers. For all we know, such measure would be counterproductive, should the two become distracted while engaging in heated debates over the previous night’s Dodger’s game.
Amtrak-style train service, such as Metrolink, is notorious for low employee productivity. Most transit agencies (outside the US) run commuter service with just a single crewman (i.e. the driver), using Proof-of-Payment ticketing in lieu of conductors. Whereas “safety” regulations and make-work rules in the US necessitate all kinds of extra labor expenses — ticket punchers, ticket sellers, and now an extra train driver too.
There is also significant opportunity cost that comes with hiring superfluous drivers. Their salary comes at the expense of real safety measures; for example, hiring extra patrols at problem intersections to ticket car drivers going around crossing gates.
Systemic Failure 
Someone tell Senator Boxer to back off.
Maybe tell her to support increased positive train control funding.