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Mobile5b - Tier2 Analysis Version
5/18/98
U.S. Environmental Protection Agency
Office of Transportation and Air Quality
1.0 Introduction
The Tier2 Analysis version of Mobile5b gives users greater capabilities for entering user-defined Basic Emission Rate (BER) equations. The Tier2 Analysis version allows users to enter up to 25 user-defined BERs for each combination of vehicle type, pollutant, and region (high or low altitude). The standard version of Mobile5b allows only 12 BERs for each combination. In addition, the Tier2 Analysis version of Mobile5b allows users to enter the kink points that will be used for each BER. The kink points can be entered for any model year for all vehicle types. In all other respects, the Tier2 Analysis version of Mobile5b is identical to the standard version of Mobile5b.
2.0 Inputs
The input format for user-defined BER equations in the Tier2 Analysis version of Mobile5b is very similar to the format used in the standard version. In the Tier2 Analysis version, one extra field has been added to the input record. This field, which is optional (it may be left blank), is used to enter the kink points that should be used for each BER equation. The kink points are entered in F6.2 format as vehicle miles scaled by a factor of 10,000. For example, the standard kink point assumed in the standard version is 50,000 miles. This value would be entered as 5.00 in the last field of the Alternate BER record in the Tier2 Analysis version.
For emission factor calculations which use the Mobile5b default values for BERs, the kink points will be applied automatically just as they are in the standard version for the appropriate vehicle types and model years. In the Tier2 Analysis version, no kink point will be applied for a user-supplied BER unless it is explicitly entered on the Alternate BER record. If no kink point is entered, the emission factors will be calculated using a straight linear equation based on the DR1. Any value entered for the DR2 will not be used in the emission factor calculations. In the standard version of Mobile5b, kink points are supplied by default, even for user-supplied BERs. This incompatibility between the Tier2 Analysis version and the standard version of Mobile5b allows users to investigate the effects of BERs without kink points for any model year and vehicle type.
There is another possible incompatibility between the Tier2 Analysis version and the standard version of Mobile5b. The Tier2 Analysis version uses columns 34 through 39 of the Alternate BER record as the input field for the kink point. If no kink point is entered, this field must be blank. Many existing Mobile5b input files have comments or other characters in these columns which will cause data format errors that will halt the execution of the Mobile5b model.
Each group of Alternate BER records is preceded by a header record which consists of a single integer field which shows the number of Alternate BER records that will follow in the input file. The format of this field has been changed from I3 in the standard version of Mobile5b to I4 in the Tier2 Analysis version. The maximum number of Alternate BER records that the user can enter in the Tier2 Analysis version of Mobile5b is 1,200.
Two records from a typical input file for the Tier2 Analysis version of Mobile5b are shown below.
30 The number of new basic emission rates (BER) to be entered 1 5 2 82 86 0.286 0.105 0.271 5.00 A kinked DR for LDDT
The first record gives the count of the number of Alternate BER records that will follow in the input file. The format or this record is I4. In this example the count is 30. The columns following the input field can be used for comments, as shown above.
The second record is a typical Alternate BER record. The format of this record is I1,1X,I1,1X,I1,1X,I2,1X,I2,4(1X,F6.2). This example describes a BER for a low altitude (1) Light Duty Diesel Truck (5). The equation is for carbon monoxide (2) for the model years 1982 (82) through 1986 (86). The Zero Mile Level (ZML) for this equation is 0.286, the first slope, or deterioration rate (DR1), is 0.105, the second slope, or deterioration rate (DR2), is 0.271, and the second deterioration rate will be used (the equation will be kinked at) 50,000 miles (5.000). The kink point is entered as miles scaled by a factor of 10,000. Comments may also follow column 39 on this record, the last column used to specify the kink point mileage. The kink point will be used for all BER equations for any model years for all vehicle types in this version of the model.
Note that the last two numeric fields, the DR2 and the kink point, may be left blank. If the kink point is left blank (or entered as 0.0), no kink will be applied to the BER equation, even if a DR2 is entered on the record. The DR1 entered on the record will be used in the BER equation for all accrued vehicle miles. The DR2 field may also be left blank if the DR2 value is not required for the BER equation. This would be true if a straight linear equation based only on the ZML and DR1 is used for the BER because no kink point is entered on the record.
Entry of Alternate BERs for LDGV, LDGT1, and LDGT2 for 1999 can change the emission rates for these vehicles for other years as well if a LEV program is modeled for these vehicle types. The emission rates for the LEV vehicles is absed, in part, on the 1999 emission rates for the non-LEV vehicles of the same vehicle type. In addition, the I/M credits assumed by the model were derived using the standard BER rates and may be inappropriate when the BER rates are changed by the user. See sections 2.1.8.3, 2.1.20.8, and 2.2.5.1.3 of the Mobile5b User Guide for further information about these topics.
3.0 Outputs
The structure of the outputs for the user-supplied BER equations in the Tier2 Analysis version of the model is very similar to the format used in the standards version of Mobile5b. An extra field has been added for the kink point, which was not available in the standard version of the model. The output fields for the Zero Mile level (ZML), the two deterioration rates (DR1 and DR2), and the kink point have been expanded to show four places following the decimal point for greater precision. The other integer output fields have been compressed to make room for the expanded number of decimal places in the output fields mentioned above. An example of the output from the Tier2 Analysis version of the model is shown below.
0 Emission Factor Modification Profile + ____________________________________ 0 Eqn. Reg Veh Pol First Last Base DR1 DR2 KINK Altered + ____ ___ ___ ___ _____ ____ _________ _________ _________ _________ _______ 1 1 1 1 1976 1976 1.0600 0.2800 Yes 2 1 1 1 1977 1977 1.0600 0.2800 Yes 3 1 1 1 1978 1978 1.0600 0.2800 Yes 4 1 1 1 1979 1979 1.0600 0.2800 Yes 5 1 1 1 1980 1980 0.3600 0.2050 Yes 6 1 1 1 1981 1981 0.2870 0.1010 0.2850 5.0000 Yes 7 1 1 1 1982 1982 0.2860 0.1050 0.2710 5.0000 Yes
Readme (important information on use of model)
Download TIER2 model and documentation (ZIP) (320K)
Email Contact: tier2-study@epa.gov