| AECOM | Balfour Beatty | Booz Allen Hamilton (Now CH2M Hill) |
| Carter Burgess (Now Jacobs) | CH2M Hill (Now Jacobs) | Delcan |
| DMJM (Daniel, Mann, Johnson, & Mendenhall) | Elcon Associates | Gannett Fleming, Inc. |
| Hatch (LTK) | Hawaiian Dredging Cnst Co, Inc. | HDR Inc. A&E Consulting |
| Hill International | HNTB/ TK Dyer Transportation | ICF Kaiser |
| Interfleet (Now SNC-Lavalin) | Jacobs Engineering | Jakes Associates |
| Keville Enterprises | KKCS (Bay Area) | KKO & Associates, Inc. |
| Lea & Elliot | Louis Berger & Associates, Inc. | LTK (Purchased by Hatch) |
| Mott MacDonald | Multisystems | NDYLTK Norman Disney & Young + LTK |
| Parsons Brinckerhoff (Now WSP) | Parsons Transportation (PTG) | People & Processes |
| Rail Transit Consultants | Rail X Corp | RailPros |
| Raul V Bravo + Associates, Inc. RVBA | SNC-Lavalin | Stantec Consulting Inc. |
| STV Group | SYSTRA Consulting | URS Corp (Redirects to AECOM) |
| VHB - Vanasse Hangen Brustlin | Virginkar & Assoc, Inc. | |