Time management is always challenging in project management. Through proper planning project managers can avoid schedule overrun.
Project Time Management involves
# defining required activities to complete the project,
# sequencing those activities based on their dependencies,
# estimating required resources & time for each activity,
# developing a project schedule, and
# executing the activities within the estimated time limit.
Schedule overrun may affect Cost, Quality and increases risk on project success. Few scenarios that may lead to schedule overrun are:
* Required resources are not available on time
* Activities takes longer time than estimated
* More reworks identified in quality process
Project management team can identify schedule overrun and possible risks due to overrun during project status performance reviews. Having quality management plan reviewed early in planning stage, projects can get benefit of cost reduction and schedule overruns caused by rework.
Project manager can use one of the schedule compression techniques or take corrective action to bring schedule back on track. It is not required that schedule compression techniques to be used only after encountering a schedule overrun. Project manager can use it as a preventive measure for anticipated schedule overrun. Let us review the definition:
Schedule compression shortens the project schedule without changing the project scope, to meet schedule constraints, imposed dates, or other schedule objectives. 
Mainly, schedule compression is to reduce the schedule without modifying project scope. Following 2 techniques are widely used for schedule compression: 1) Crashing 2) Fast tracking
Crashing: This technique may affect project cost. Trade-off between cost and schedule is analyzed and it is used to get maximum schedule compression for a minimal cost increase.
Following may be few actions by Project managers for crashing:
* Getting resources from other projects as loan
* Paying extra for fast shipment purchased materials
* Asking team members to work for extra hours against compensatory off or overtime
* does not always be an affordable choice; and
* may result in increased risk and/or cost.
Fast tracking: By simple definition, fast tracking is getting schedule compression by executing phases or activities in parallel that were originally scheduled in sequence. Fast tracking can be achieved by overlapping of phases or activities by starting subsequent activity or phase without finishing earlier one. But overlapping phases or activities may increase risk and gives rise to more reworks.
Following may be few actions by Project managers for fast tracking:
* identify phases that can overlap and start execute next phase before finish of earlier one
* identify activities that uses different set of resources and execute them parallel
* find activities that give low risk or low cost for time when executed prior to the completion of earlier phase
Fast tracking may result in –
* Rework – extra cost/time to fix
* Increased risk
As far as these compression techniques are concerned, managers can take risks if the risks are in balance with the benefits that may be gained by taking the risks.
. PMBOK® Guide 3rd Edition