Apart from communication skills, both written and verbal, you can also train the engineers in influencing skills as the current working environment demands the need to influence people at all times.
Topics to Cover in Influencing Skills Training
The following topics can be covered:
(a) Influence to get what you want
(b) Nature of influence: your interpersonal skills, etc.
(c) Building rapport
(d) Influencing to get your point across
(e) Being assertive
(f) Influencing in groups, etc.
Regards,
Vinesh