| Abbreviation | Definition |
|---|---|
| DHC | Destination Handling Charge |
| DHH | Dual Halogen Headlight |
| DHL | Dalsey, Hillblom, and Lynn |
| DHM | Durham- UNH Amtrak Station (The Downeaster) |
| DHSP | District Highway Safety Plan |
| DHTV | Design Hourly Traffic Volume |
| DI | Driver Improvement |
| DIAL | Delhi International Airport Limited |
| DIAP | Drug Interdiction Assistance Program |
| DIFT | Detroit Intermodal Freight Terminal |
| DIP | Driver Improvement Program |
| DIRECT | Driver Information Experimenting with Communication Technology |
| DIRT | Diesel Is the Right Thing |
| DIST | Distribute |
| DIVA | Diving Instrumentation Vehicle for Environmental Research |
| DJT | Dow Jones Transportation |
| DJTA | Dow Jones Transportation Average |
| dL | Deci-Liter |
| DL | Double Log |
| DL | Drivers License |