45 minutes face to face interview and 45 minutes numerical test.
The face to face interview is more about you, why you decided to apply for AECOM or any other questions related to interviews (i.e. your strengths, your weaknesses,etc)
The numerical test might vary in relation to the department but it is mainly related to basic knowledge about the position that you are applying. For example, if you are applying for Mechanical Engineering, they might ask you about different type of air conditioning systems, drawing an schematic diagram, calculating their efficiency, heat losses, etc