September 1996

                  Frequently Asked Questions
  Regarding Use of the EPA Remote Sensing I/M Credit Utility


  NOTE:  The full user guide for the RSD utility is contained in
  the file RSDUTIL.PDF, which is an Adobe Acrobat Portable
  Document Format (PDF) file contained in RSDUTIL.ZIP.  If you do
  not yet have the free Acrobat Reader software to view/print
  this file, you can download it from the Adobe web site:
  www.adobe.com.  If you do not have internet access, then you
  can get it by dial-in modem from the TTN Bulletin Board
  (919-541-5742) in the System Utilities area. 


What do I need to know in order to estimate additional credits for
my remote sensing program that is used in conjunction with my
periodic I/M program?

       The credit will depend on the scope and details of the
  proposed remote sensing program.  You will have to specify
  information on how vehicles will be identified for repair using
  remote sensing.  The utility accepts program design inputs that
  commit to a level of effort based on the number of valid
  measurements performed, the number of unique vehicles measured,
  or the number of vehicles identified and confirmed as emission
  failures.  You will also need to know the CO emission cutpoint
  that is planned to be used to identify vehicles for
  confirmatory testing.

We don't have an I/M program.  Can I estimate the benefit of an RSD
program using the utility for this situation?

       Yes.  One option allows the utility to generate benefits
  for a RSD program even if there is no pre-existing periodic I/M
  program in place for the entire vehicle fleet.  However, it is
  assumed that the failed RSD vehicles will receive a
  confirmatory I/M test at a designated station, get repaired,
  and return to the station for an I/M retest. The special remote
  sensing credits are then used in the MOBILE5 model as though
  there were an I/M program for those vehicles failing RSD in
  order to calculate the remote sensing program benefits.

We intend to use remote sensing readings to identify vehicles to be
exempted from our periodic I/M program.  How do I model that?

       The use of remote sensing devices to exempt clean vehicles
  from your periodic I/M program is useful to increase public
  acceptance and the cost benefit of I/M. However, using RSD in
  this manner will not increase your I/M credit. The utility does
  not have an adjustment for the use of remote sensing readings
  to exempt vehicles from a periodic I/M program. EPA will work
  on criteria to optimize the use of remote sensing to exempt
  vehicles from the periodic I/M program.

We intend to use remote sensing to measure HC (and/or NOX)
emissions.  How do I model that?

       The RSD utility currently estimates the HC, CO, and NOX
  emission impact of identification of vehicles using remote
  sensing concentration readings of carbon monoxide (CO). The CO
  emission measurements are the most developed and have the most
  data available. Additional capabilities to obtain HC or NOX
  impacts when identifying vehicles based on HC or NOX RSD
  concentrations will need to be added as the information becomes
  available.  How does one determine how much additional
  benefit my remote sensing program adds to my periodic
  inspection program?

       The utility generates new credits for the combined
  periodic inspection program with the remote sensing option
  described by the user.  The remote sensing program benefits are
  handled as an increment to the existing I/M program.  Multiple
  MOBILE5 model runs, with and without the new credits, will be
  needed to determine the incremental (additional) benefits of
  the remote sensing portion of the inspection program.

I have an annual I/M program.  How do I model the benefits of a
remote sensing program?

       The current remote sensing benefit methodology bases the
  additional emission reductions on the assumption that the
  vehicles identified by the remote sensing program undergo an
  increase in their periodic inspection frequency.  Since MOBILE5
  only estimates emission benefits up to an annual frequency for
  a test-only program, there is currently no estimate for the
  benefits of frequencies greater than annual.  As a result, the
  utility cannot estimate the potential benefits of adding a
  remote sensing program to an existing annual I/M program.  The
  utility will account for vehicles identified by the remote
  sensing program which are diverted to inspection stations that
  are more stringent (such as using an IM240 test procedure) than
  the periodic I/M program, even for an annual frequency.  Thus,
  some credit is given for adding RSD to an annual I/M program
  with a significant test-and-repair discount where the vehicles
  failing RSD receive a more stringent confirmatory I/M test.

How does the utility handle the increased vehicle owner compliance
with the periodic I/M program expected with the addition of the
remote sensing program?

       The utility makes no assumptions about the compliance with
  the I/M program.  There is an input in the MOBILE5 model which
  allows the user to specify the compliance rate for the program.
  If increased compliance is expected or measured, that effect
  can be entered directly into the MOBILE5 model run. 

How does the technique of requiring multiple remote sensing readings
at different times affect the estimated benefits?

       The current default values used to determine the benefits
  of remote sensing options do not account for the effects of
  multiple readings.  The data necessary to make those
  adjustments were not yet available and the methodology to use
  such information has not been investigated.  This information
  is now becoming available and EPA plans to modify the RSD
  utility either before or when MOBILE6 is released.

What is the relationship between this guidance and the National
Highway System Designation Act?

       The National Highway System Designation Act provides for
  an 18-month evaluation of each I/M program to determine if the
  I/M program is as effective overall as the good faith estimate
  made earlier.  The good faith estimate for program
  effectiveness is focused on estimating the emission reduction
  loss or discount for test-and-repair I/M programs.  Having an
  estimate of this discount is needed to estimate Remote Sensing
  Credits for test-and-repair I/M programs. Remote sensing itself
  though can be one component of an I/M program to be evaluated
  under the National Highway System Designation Act.