Vehicle Emissions Prediction Model (VEPM)


The Vehicle Emissions Prediction Model (VEPM) is used to predict emission factors for New Zealand fleet vehicles that could be found under typical road, traffic and operating conditions.


VEPMs intended use is for emission estimation at road network level. It is well suited for scenario testing and modelling future developments and road use predictions with a focus on quantifying vehicle emissions and predicting how these are likely to change over time.

VEPM can be used as an input component in conjunction with other models when predicting the effects of proposed infrastructure changes on surrounding areas.


VEPM in the assessment process

VEPM - Assessment Process

VEPM was developed for Auckland Council (AC) and released for use in 2008 as v3.0 with subsequent updates and refinements since then (at the time of writing version 5.3 is available). The model was developed with the aim of quantifying vehicle emissions with specific focus on New Zealand’s vehicle fleet.

The VEPM model predicts emission species including CO, CO2, VOC (Volatile organic compounds), NOx, NO2, PM2.5 (Exhaust), PM (Brake &Tyre) & FC (fuel consumption) for a variety of input class vehicles and scenario conditions i.e. vehicle size, average speed, fuel type, gradient & load. VEPM also provides the option to calculate brake and tyre wear particulate emissions based on the average number of wheels for each vehicle class.

The VEPM is a password protected Excel spreadsheet which is publically available upon request from the New Zealand Transport Agency (NZTA) (; just add “Vehicle Emissions Prediction Model” in the subject line. On the NZTA website full access is available to current model downloads and current user guides.    


VEPM Worksheet inputs

 VEPM Worksheet


The VEPM runs on a variety of input data which is added by the user to the work sheet this include both required and optional inputs based on availability;

  • Analysis year (between 2001 and 2040)
  • Run number
  • Average Speed
  • Fleet profile (Optional user entry)
  • Average trip length (Optional user entry)
  • Ambient temperature (Optional user entry)
  • Fuel type considered? (Optional user entry)
  • Consider cold start? (Optional user entry)
  • Gradient (Optional user entry)
  • Load(Optional user entry)
  • Number of wheels

Latest Version VEPM V5.3 (April 2017)
State of Development Released and updated

Development Contact

New Zealand Transport Agency


Outcome Areas Environmental
Management Domains Air Quality
Subdomains Air Emissions Inventories
Intended End Users
  • Regional Council Scientist
  • Policy Analyst
Steady State or Dynamic Unknown

Input & Output Data

Key Input Data Average speed for vehicle types, fleet profiles, climatic variables
Input Data Formats XLS(X)
Key Output Data Emissions (CO, CO2, VOC, NOX, NO2, PM)
Output Data Formats XLS(S)


Open/Closed Source Closed Source
Licence Type No Licence

User Information

Operating Systems MS Windows
Software Needed MS Excel
User Interface Graphical desktop
Ease of Use Easy
Use in Policy Process Plan (Policy Formulation), Review (Issue Identification)

Vehicle emissions prediction model (VEPM 5.3) update - technical report - April 2017 [PDF, 1.1 MB]

Vehicle emissions prediction model (VEPM 5.3) user guide v2.0 - April 2018

Technical Considerations

Model Structure

VEPM model workflow


See NZTA website - Vehicle emissions prediction model