Yes you can apply for Traffic & Transportation Engineering field jobs after passing M tech civil engineering course .
Here I am giving you information about current Traffic & Transportation Engineering field jobs as on June 2014 by online source below:

Traffic and Transportation Engineer
Job-Astro Consultants - Delhi, DL

Senior Traffic Engineer / Transportation Planner
Job-Astro Consultants - Kolkata, WB

Traffic and Transportation Expert
Bslnoida_1 - Jaipur, RJ

TRAFFIC AND TRANSPORTATION EXPERT
Job-Astro Consultants - Delhi, DL

Traffic Engineer
Job-Astro Consultants - Kolkata, WB

Traffic & Transportation Engineers at ENARCH Consultants Pvt. Ltd.
Enarch Consultants - Noida, UP

traffic assistant (checker)
Plus Placement (Bhopal, MP)

Traffic Modeling Engineer - Basra -
Hill International (Mumbai, MH)