Common shortfalls in manpower assignment in project management include:

1. **Insufficient Skill Matching**: Assigning team members to tasks that do not align with their skills and expertise can lead to inefficiencies and errors.

2. **Overloading Resources**: Sometimes project managers underestimate the workload, leading to over-assignment of tasks to individuals, which can result in burnout and decreased productivity.

3. **Poor Communication**: Lack of clear communication about roles and responsibilities can cause confusion and overlap in tasks, compromising project timelines.

4. **Inflexibility**: Not allowing for flexibility in role assignments can hinder responsiveness to project changes or unforeseen challenges.

5. **Ignoring Team Dynamics**: Failing to consider the interpersonal dynamics of the team can lead to conflicts and lowered morale, affecting overall performance.

6. **Neglecting Training and Development**: Not providing adequate training opportunities can leave team members underprepared for their assigned tasks.

7. **Inadequate Resource Planning**: Failing to forecast project needs accurately can lead to a shortfall or excess of manpower, impacting project schedules and budgets.

8. **Underestimating Project Complexity**: Misjudging the complexity of project tasks may result in improper allocation of manpower, leading to delayed or failed project outcomes.

By addressing these shortfalls, project managers can enhance the effectiveness of their manpower assignments and improve overall project success.