From Travel Model To EMFAC

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This page is still under development.

As part of MTC’s work on Plan Bay Area 2050, our analysts updated and created several new scripts to automate some of the steps for feeding Travel Model outputs into EMFAC. This page describes which steps are automated and which steps are still to be done manually.

The flowchart below shows the detailed workflow from the Travel Model to EMFAC; and the paragraphs below describe the steps to be undertaken by the analyst in order to run EMFAC.

How to run EMFAC

Soon after the third iteration of a model run is completed, the batch script RunPrepareEmfac.bat will be automatically run as part of RunModel.bat. (See: https://github.com/BayAreaMetro/travel-model-one/blob/master/model-files/RunModel.bat#L359). A “custom activity template” with hourly distributions of VMT by speed bin, vehicle technology¹ and subarea² from the Travel Model would be generated as a result. It will be named as “ready4emfac_[run_id].xlsx.

While RunModel.bat will continue to run the scripts for producing logsums, core summaries and metrics, the analyst can proceed to run EMFAC in parallel on a different server. At MTC we typically use the server Mainmodel for EMFAC runs, as it has EMFAC2014 and EMFAC2017 installed.

To run EMFAC, the analyst can follow the on-screen instructions or the instructions on the "Run EMFAC" page. (Here: https://github.com/BayAreaMetro/modeling-website/wiki/Run-EMFAC)

On the MTC server Mainmodel (add machine specs), EMFAC takes about 1.5 hours to complete.

Footnotes:

1: Note that the Travel Model does not simulate the detailed vehicle technology categories that are in EMFAC. Thus, the same hourly distributions from the Travel Model are assumed for each subarea-hour combination. Additionally, the hourly distributions from the Travel Model are applied only to the nine vehicle technologies included in SB375 analyses. For all other vehicles types, the default hourly distributions from CARB are kept.

The nine vehicle technology are:

• Passenger cars – diesel (LDA – Dsl)
• Passenger cars – gasoline (LDA – Gas)
• Light-Duty Trucks, with GVWR < 6000 lbs and ETW <=3750 lbs – diesel (LDT1 – Dsl)
• Light-Duty Trucks, with GVWR < 6000 lbs and ETW <=3750 lbs – gasoline (LDT1 – Gas)
• Light-Duty Trucks, with GVWR < 6000 lbs and ETW 3751-5750 lbs – diesel (LDT2 – Dsl)
• Light-Duty Trucks, with GVWR < 6000 lbs and ETW 3751-5750 lbs – gasoline (LDT2 – Gas)
• Motorcycles – gasoline (MCY – Gas)
• Medium-Duty Trucks, with GVWR 6000 and 8500 lbs – diesel (MDV – Dsl)
• Medium-Duty Trucks, with GVWR 6000 and 8500 lbs – gasoline (MDV – Gas)

For more details, see appendix 4 in the EMFAC2017 user guide (https://ww3.arb.ca.gov/msei/downloads/emfac2017-volume-i-users-guide.pdf).

2: There are 11 subareas (in the Bay Area, there are nine counties but Solano and Sonoma have two air basins). They are: Alameda (SF); Contra Costa (SF); Marin (SF); Napa (SF); San Francisco (SF); San Mateo (SF); Santa Clara (SF); Solano (SF); Solano (SV); Sonoma (SF); and Sonoma (NC).

Detailed workflow: From the Travel Model to EMFAC

For a clickable version of the flowchart below, view it in diagrams.net

How to generate a regional level summary after EMFAC is done

To obtain a concise summary of the EMFAC results at a regional level, the emfac_postproc.py script can be run. This script can be run from any machine that has Python 3 installed. The steps to run it are as follows:

C:\>cd /d A:\Projects\2050_TM152_FBP_PlusCrossing_16
A:\Projects\2050_TM152_FBP_PlusCrossing_16\>python ctramp/scripts/emfac/emfac_postproc.py SB375 "M:\Application\Model One\RTP2021\Blueprint\2050_TM152_FBP_PlusCrossing_16"

This script takes only a couple of seconds to run, and the output will be placed in two locations:

• emfac_prep\emfac_ghg.csv within the directory of the full model run, and
• \OUTPUT\metrics\emfac_ghg.csv in the model output directory on the M drive