This paper presents a status report on a preliminary survey of strategies that might be employed to meet US-EPA 1991 heavy duty diesel emission standards without the use of a particulate trap. Although the survey of strategies is not yet complete, that portion dealing with the swirl supported diesel combustion process is sufficiently advanced to allow this status report to be published. It is anticipated that future related reports will provide a view of the complete survey, including quiescent combustion process. This report describes the techniques employed for the steady state approximation of the heavy duty transient test cycle and the analytical procedures used to characterize the particulate composition in terms of insolubles, and the fuel and lube oil related components. Results of tests of the essential combustion system parameters are presented and several of the important trade-off relationships are discussed, suggesting, in a preliminary sense, some of the development approaches which have the potential to satisfy the 1991 HD standards.