Checking the logic on light rail

Apparently, advocates of high speed light rail in California are arguing that two rail lines are the equal of six to eight highway lanes.  Let's check that assumption.  You have one rail line each way versus three to four highway lanes each way.  What is peak capacity?

Well, if what I learned in drivers' ed is indicative, you can have a car every four or five seconds, generally with one or two people on it, and quite frankly you can run a bus every ten seconds or so without endangering anyone.  So a lane of traffic can carry about 900 vehicles per hour--legitimately up to 2000 people or more.  So those three or four lanes can carry 3000 to 8000 people per hour, plus trucks and buses.  If one in ten vehicles is a bus with 30 people on it, each lane could carry as many as 5000 people per hour.

OK, now a rail line.  If you get more than one train every ten minutes, you're really going to run into timing issues, and if you have more than three or four cars per train, you're stretching the limits of mass transit there.  If there are 50 people per carriage, we have up to 200 people per train with six trains per hour, for a maximum of 1200 riders per hour.

In short, the $98 billion California high speed rail idea would achieve about the same as not four, but rather one, lane of traffic in each direction.  Now the cost of one lane each way; apart from buying the rights of way, a lane of highway each way costs about $10 million per mile when done in good reinforced concrete, for a total of about five to ten billion dollars.

In the same way, to get 1200 passengers per hour, you need about 50 more airliners for....about five to ten billion dollars.  So once again, high speed light rail is....at ten times the cost of competitive technology, a solution in search of a problem.

Note: yes, you could theoretically "squeeze" in longer trains with more passengers, but trying to run them more often while maintaining a safe following distance for trains running on steel wheels at 250mph--I'm guessing that's measured in miles just as it is with planes--is going to be very, very difficult, as the horrific deaths in China's high speed lines demonstrate.  Here's an example of a more responsible schedule from Chicago, one of the two or three most rail-dependent cities in the nation.