| Business | Phone |
| Charles R Johnson Civil Engrng 2905 Fox Mill Rd, Herndon 20171 | (703) 758-7758 |
| Core States Engineering Inc 297 Herndon Pkwy # 302, Herndon 20170 | (703) 796-0700 |
| Dr G Sauer Corp 11550 Southington Ln, Herndon 20170 | (703) 450-5511 |
| Dr G Sauer Corp 560 Herndon Pkwy # 310, Herndon 20170 | (703) 709-0700 |
| Gdn Engineering Inc Herndon 20170 | (703) 318-3100 |
| Tri-Tek Engineering Inc 690 Center St 300, Herndon 20170 | (703) 481-5900 |
| Ltm Inc 1407 Cuttermill Ct, Herndon 20170 | (703) 787-8831 |
| Parsons Brinckerhoff Quade 465 Springpark Pl, Herndon 20170 | (703) 742-5700 |