Comment Log Display

RTAC Members and ARB Staff:

I can't comment on the newer marked-up draft, as I can't get the
copy I received to print or to edit.  I'll comment on the next
round that is put on the web site. 

I'll keep it brief:

1. A standard set of performance indicators is needed and it must
include VMT and on-road GHGs by vehicle type and time of day, so
reviewers can check the outputs for reasonableness. And so we can
all compare outputs across MPOs. Without a standard set of
indicators, the whole SB 375 process is worthless. We also need
mode shares, VHT, and other travel indicators. And land use
indicators for new uses, such as density and mix and access to
transit. 

2. A standard set of Alternatives must also be required, again in
order for reviewers to determine the reasonableness of the SCS and
APS scenarios.  I suggested a set in my two previous comments (No
Action, Strong Transit, Strong Transit Plus Supporting Land Use,
Strong Transit Plus Supporting Land Use Plus Pricing of Parking
and/or VMT). These will be defined somewhat differently by each
MPO, but they will allow comparison across scenarios within an MPO
and broad comparison across MPOs. Other alternatives can be done,
of course, as the MPOs wish. These standard alternatives also serve
as a useful sensitivity test of each MPO's models. It is very
difficult to review a modeling exercise if the alternatives are
muddled, that is, have various mixtures of policies and no pure
scenarios. The current CTC modeling guidelines urge sensitivity
testing, along these lines.  

3. The Pavely and the LCFS policies' effects should be kept out of
the SB 375 analyses, to the extent possible, by focusing on VMT and
on-road GHGs and by presenting the GHG projections with a standard
fleet that doesn't change from the Base Year, so we can see the
effects of SB 375 alone.  Only in this way, can one evaluate the
progress over time of the SB 375 policies and judge the validity of
the modeling. One can also run the EMFAC model with the projected
(changing) future fleets to get the real GHG projections. 

4. I would make the metric: Change in GHGs/(pop.+ empl.).  One can
then break this metric into two, with denominators of New Growth in
Pop. and Empl. and of Existing Pop. and Empl. Both new population
and new employment can be regulated so that they are built at
higher densities. So, growth in both of these variables jointly can
be used in setting the GHG-reduction targets. If you only use
growth in population, you will not be able to fairly  handle MPOs
where employment grows much more rapidly than population. Trips in
models begin at Households (pop.) and end at Employment. Both
activities are equally responsible for trip generation. Both are
necessary in a travel model, to get a trip. Both are equally
important in the real world, too.  

5. I would not allow the SST/BMP approach to be used in final MPO
SCS or APS modeling, except for small MPOs without travel models.
This approach will not be as accurate as running a travel model and
doing post processing with empirically derived spreadsheets,
applied to the local travel data. And it cannot be checked for
reasonableness, except in a very general way.

BMPs, though, should be identified by each Air District that
covers one or more of the SB 375 MPOs and adopted, as is now  done
with air pollution BMPs. Please explicitly recommend to the ARB
that the air districts have this supplementary role in implementing
this statute. 

Thank you for your consideration of these ideas. I have reviewed
many MPO modeling exercises and wish to make this process workable.


Bob Johnston, Professor
UC Davis