From: jeremy@classic.asd.sgi.com (Jeremy Higdon)
Newsgroups: ba.transportation
Subject: Re: "The only sensible way to proceed"
Date: 28 Aug 92 20:44:02 GMT
Distribution: ba
Organization: Silicon Graphics, Inc.  Mountain View, CA

In article <17km8gINN3vv@darkstar.UCSC.EDU>, fuzzface@cats.ucsc.edu (Aaron Priven) writes:
> 
> In article <p327t50@sgi.sgi.com> jeremy@classic.asd.sgi.com (Jeremy Higdon) writes:
>  
> >If total annual boardings
> >for Muni is 300 million and total annual boardings for Caltrain
> >is 20 million, I don't need the MTC to say that total annual
> >boardings for Caltrain and Muni combined is 320 million!
>  
> No, but you shouldn't criticize them for having meaningless 
> figures if the figures are yours.  You wrote (in 
> <p1ddvfk@sgi.sgi.com>) that 

I don't see that combined boardings is any more meaningless than
individual.  The fact that Caltrain and Muni are counted separately
is only an artifact of the current political structure.


>  
> >>>This example shows the problem with these studies and the first
> >>>level conclusions that can be drawn from them. 
>  
> I don't think it says anything about the study if you draw a 
> conclusion from it that is unwarranted.  You're the one drawing 
> conclusions.

Sorry, I was being imprecise.  I also didn't know about the table
below.


>  
> >Nor would I say that 320 million was any more meaningless
> >than the 300 million or 20 million figures.  In fact, if
> >Caltrain and Muni were under the same management, you would
> >only see the one figure in these studies.
> >
> >The point of my article was that total annual
> >boardings can be misleading, especially when it is called
> >ridership (which it often is).
>  
> Fine, but you called it ridership, not them.  They weren't 
> trying to measure ridership.  They were trying to measure system 
> usage, which is why boardings was on the same table as "fleet 
> vehicles" and "total vehicle miles".  Perhaps the fault is mine 
> for repeating that data.

That's true.  They were being more precise.  However, when light
rail ridership is quoted at 23000 per day, they really mean
boardings.  Newspapers don't distinguish.  Just trying to point
that out (not very well, apparently . . . .)


>  
> Maybe this is the table I should have quoted:
> 
>                             Table 4.6
>        Regional Transit Person Trips (Linked Trips) (1,2) 
>                  By Alternative and Trip Purpose
>                        2010 Daily Volumes
>  
>                                   SFO Air              Change (4)      
> Alter-     Work        Non-Work   Passen-              from TSM 
> native     Trips       Trips      gers (3)   Total     (2A/2B)                
>  
> Base Year
> 1987       441,300     452,200    11,400    904,900    -378,500
>  
> 1          586,800     662,800    17,900    1,267,500  -15,900 to -20,900
> 2A         597,000     665,100    21,300    1,283,400  --
> 2B         601,000     665,600    21,800    1,288,400  --
> 5A         603,900     665,100    25,200    1,294,200  10,800
> 5B         606,000     666,300    25,800    1,298,100   9,700
>  
> (1) The region is defined as the 9-county Bay Area region...
> (2) Linked trips may involve use of one or more transit systems, but the 
> total trip from origin to destination is counted as one transit trip.
> (3) Includes "Well-wishers" (i.e., persons dropping off or picking up air 
> travellers).  Includes all transit modes to SFO (i.e., BART, CalTrain, 
> SamTrans, and the Airporters).
> (4) Change is from Alternative 2A for existing (1987) and Alternatives 
> 3A, 4A, 5A, and 6A.  Change is from Alternative 2B for Alternatives 3B, 
> 4B, 5B, and 6B.


This table makes it much clearer.  The previous table could lead
to erroneous conclusions, as I pointed out (where you thought I
was concluding, but I really was just saying that people (or
newspapers or politicos) could conclude, etc. . . . .).

jeremy