A project plan helps a project manager (PM) track project tasks to a budget over time and it allows the PM to keep management informed of progress. A high-level version of a plan is management-oriented and serves the latter purpose more than the former.
Project plans vary in detail and scope depending on their audience and purpose, but when speaking of a high-level plan, managers generally are concerned with approving a project before its initiation and then tracking it at the executive or program management level.
A vital topic in high-level project plan is the expected outcome. A project manager will explain in writing the purpose of a project and highlight the expected benefits. Ultimately, the project will create something of value that should be measurable in terms of revenue, cost savings, customer satisfaction, quality metrics, or other relevant parameter.
The plan will include a timing estimate. Assuming that the PM will deliver something of value, people will be awaiting its delivery. Having a good idea of that delivery date allows the recipients of the project's deliverable to plan ahead for putting the deliverable to good use. Additionally, timing estimates are a major input to scoping costs.
The project will incur the potential costs of capital equipment, facilities usage, utilities, technical licenses and staffing. Decision makers need to balance the estimated cost of a project against the expected outcomes to determine if the project is worth the expense. The cost forecast also serves as a baseline for tracking the progress of a project and later determining of cost overruns require terminating it before completion.
Milestones and Gates
A high-level plan will include future reviews by management. Management will expect to see interim deliverables or accomplishments called milestones. The significance and definition of a milestone is subject to interpretation of those writing and reading the plan, but it's designed to serve as a marker toward the desired outcome.
Gate reviews are designed to allow managerial decision making to terminate a project or allow it to continue, and they will be scheduled into the high-level plan.
Risks and Mitigation
Projects can stall or experience cost overruns based upon certain predictable undesirable outcomes, such as a key vendor going bankrupt, adverse currency fluctuations for internationally sourced products, or technical challenges that prove too complex to resolve. The PM will address these as risks in the high-level plan and assess their impact on the project. If the impact is severe enough to pose a threat to the project, the PM will also address mitigation tactics to overcome these risks, such as identifying an alternative vendor or purchasing a futures contract as a currency hedge.