3. Methodology¶

3.1. General¶

The project folder for using the tool should contain an “inputs” folder containing necessary input files and a “tool_code” folder containing the Python modules. Optionally, a virtual environment folder may be desirable. When running the tool, the user will be asked to provide a run ID. If a run ID is entered, that run ID will be included in the run-results folder-ID for the given run. Hitting return will use the default run ID. The tool will create an “outputs” folder within the project folder into which all run results will be saved. A timestamp is included in any run-results folder-ID so that new results never overwrite prior results.

3.2. Scenario names in output files¶

Because many of the model runs done in support of the NPRM involved split fleets (CA framework vs. non-framework OEMs), some scenario names attempt to indicate both the fleet involved and the standards being met. Scenarios included in the primary runs are shown in Table 1.

Table 1

Scenario Name	Description
2020hold	Full fleet meeting the 2020 standards for 2020+
Safe	Full fleet meeting the SAFE FRM standards through 2026 and thereafter
2012frm	Full fleet meeting the 2012 FRM standards
Fw27	Full fleet meeting the CA FW 2.7% year-over-year standards
Framework_Safe	FW-OEMs meeting the FW; NonFW-OEMs meeting SAFE
Fw-To-Proposal_Safe-To-Proposal	FW-OEMs meeting the FW thru 2022 then the Proposalfor 2023+; NonFW-OEMs meeting SAFE thru 2022 then the Proposal for 2023+
Fw-To-Proposal_Safe-To-Proposal-No-Mult	FW-OEMs meeting the FW thru 2022 then the Proposal for 2023+; NonFW-OEMs meeting SAFE thru 2022 then the Proposal for 2023+ (no multipliers in these runs)
Framework-To-Alternative1_Safe-To-Alternative1	FW-OEMs meeting the FW thru 2022 then Alternative 1 for 2023+; NonFW-OEMs meeting SAFE thru 2022 then Alternative 1 for 2023+
Framework-To-Alternative2_Safe-To-Alternative2	FW-OEMs meeting the FW thru 2022 then Alternative 1 for 2023+; NonFW-OEMs meeting SAFE thru 2022 then Alternative 1 for 2023+
Safe-To-Proposal	Full fleet meeting SAFE thru 2022 then the Proposal for 2023+
Safe-To-Alternative1	Full fleet meeting SAFE thru 2022 then Alternative 1 for 2023+
Safe-To-Alternative2	Full fleet meeting SAFE thru 2022 then Alternative 2 for 2023+
Safe-To-Proposal-No-Mult	Full fleet meeting SAFE thru 2022 then the Proposal for 2023+ (no multipliers)

3.3. Calculations and Equations¶

This is not meant to be an exhaustive list of all equations used in the tool, but rather a list of those that are considered to be of most interest. The associated draft Regulatory Impact Analysis (RIA) also contains explanations of calculations made.

3.3.2. Discounting¶

Monetized values are discounted at the social discount rates entered in the SetInputs class. The default values are 3% and 7%. Values are discounted to the year entered in the SetInputs class. The default value is 2021. Monetized values are discounted assuming costs occur at the beginning of the year or the end of the year as entered in the SetInputs class. The default value is “end-year”, meaning that any monetized values in 2021 are discounted.

Importantly, all emission-related monetized values are discounted at their internally consistent discount rates, regardless of the social discount rate. The internally consistent discount rate is indicated in the cost-factor input files (cost_factors-criteria.csv and cost_factors-scc.csv) in the heading (e.g., values using the “co2_global_5.0_USD_per_metricton” cost factor will always be discounted at 5%, regardless of the social discount rate).

3.3.2.1. Present value¶

(11)¶\[PV=\frac{AnnualValue_{0}} {(1+rate)^{(0+offset)}}+\frac{AnnualValue_{1}} {(1+rate)^{(1+offset)}}+\cdots+\frac{AnnualValue_{n}} {(1+rate)^{(n+offset)}}\]

where,

PV = present value
AnnualValue = annual costs or annual benefits or annual net of costs and benefits
rate = discount rate
0, 1, …, n = the period or years of discounting
offset = controller to set the discounting approach (0 means first costs occur at time=0; 1 means costs occur at time=1)

Note that the output files of present values are cumulative sums. Therefore, the results represent present values through the indicated year.

3.3.2.2. Annualized value¶

When the present value offset in equation (11) equals 0:

(12)¶\[AV=PV\times\frac{rate\times(1+rate)^{n}} {(1+rate)^{(n+1)}-1}\]

When the present value offset in equation (11) equals 1:

(13)¶\[AV=PV\times\frac{rate\times(1+rate)^{n}} {(1+rate)^{n}-1}\]

where,

AV = annualized value of costs or benefits or net of costs and benefits
PV = present value of costs or benefits or net of costs and benefits
rate = discount rate
n = the number of periods over which to annualize the present value

Note that the output files of annualized values represent values annualized through the given year.

3. Methodology¶

3.1. General¶

3.2. Scenario names in output files¶

3.3. Calculations and Equations¶

3.3.1. Total social costs, social benefits and net social benefits¶

3.3.1.1. New parameters calculated within each scenario¶

3.3.1.1.1. FatalityCosts_Net¶

3.3.1.1.2. NonFatalCrashCosts_Net¶

3.3.1.2. New or revised parameters calculated relative to a base scenario¶

3.3.1.2.1. Total Costs¶

3.3.1.2.2. Fuel Savings¶

3.3.1.2.3. Refueling Time Savings¶

3.3.1.2.4. Energy Security Benefits¶

3.3.1.2.5. Non-Emission Benefits¶

3.3.1.2.6. Emission Benefits¶

3.3.1.2.7. Total Benefits¶

3.3.1.2.8. Net Benefits¶

3.3.2. Discounting¶

3.3.2.1. Present value¶

3.3.2.2. Annualized value¶