This paper presents the results of an in-use emissions testing program which investigated the emissions and duty cycles from five heavy-duty construction vehicles. The program examined the emission reduction potential of various retrofit control technologies including; diesel oxidation catalysts, passive particulate filter, and active particulate filter technologies. Analysis of the results are provided for both the original vehicle configuration and with the vehicles retrofitted with exhaust aftertreatment systems. The vehicles studied included a dump truck, two wheeled loaders, a backhoe and a bulldozer. The paper will discuss in-use heavy-duty vehicle emissions and the use of emissions control technologies.