February 12, 2015

MEMORANDUM

SUBJECT:	Vocational Vehicle Drive Cycle Data:  Draft Report produced by the National Renewable Energy Laboratory entitled "The Development of Vocational Vehicle Drive Cycles and Segmentation"

FROM:	Lauren Steele, Environmental Engineer, OTAQ/ASD

TO:	Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles - Phase 2 - Docket EPA-HQ-OAR-2014-0827

Introduction

      Attached to this memo is a draft report produced under the direction of EPA by the National Renewable Energy Laboratory (NREL) under Interagency Agreement IAG-14-1954 and Task Number WFGY.1000.  Also attached is a set of Powerpoint slides summarizing the progress of the NREL work and offering a brief overview of the vocational vehicle Phase 2 program as of December 2015.

      The report describes the methodology and results of NREL's vocational drive cycle analysis. The vehicles included in the Fleet DNA database have been grouped into representative segments via drive cycle analysis, and membership in segments has been correlated with vehicle chassis characteristics. In proposed rulemaking, the ARB Transient cycle was combined with the 55 mph cruise cycle with road grade, the 65 mph cruise cycle with road grade, and a 10-minute idle cycle to create a 4-part composite cycle.  As a part of NREL's work, for each segment of vocational vehicles appropriate weightings were assigned to each constituent test cycle to ensure that the overall (composite weighted) cycle reasonably represents the activity of most vehicles in each segment.
      
