Planning VS Execution is very funny when you do not have a proper planning, monitoring, and controlling system. When there are big deviation between the plan and the execution the construction team start to develop their own plans. In my opinion, if the deviation exceeded 5% the project will be in dangerous situation. Following are the Main reasons of Planning VS Execution variances:

1- Planning:

• If the planning is not accurate, the site will not follow the plans and you can find deviations starting from day 1.
• Site team and Project manager are not involved in the planning. This is major mistake by Planning Engineers, you need to involve the project team to ensure their accountability to your plans.
• If the planning is too slow, the construction team will not wait for the planning team. Accordingly, they will start by their own plans and if the planning cannot modify the plans to match the site conditions, it will be another reason for Planning VS Execution deviation.
• Plans are too much detailed : When the plans involved too many pages without proper visualization, the site team feels it is very hard to read and understand.
• Plans does not cover 100% of the project scope of work: when this happens, you as a planning engineer force the construction team to use their own plans.

2- Execution:

• Project Manager is not project management literate. When the PM does not pay attention to project management, defiantly s/he will not pay attention to Planning plans.
• I know more than planning: Some site engineers have the feeling that they executed 10’s of similar projects and therefore they do not need the planning assistance. However, if you asked them out of these 10’s projects how many was completed on time, on budget, and without defects you may be surprised.
• Site Conditions is above the plans: This is correct but when the plans does not work, you need to change the plan NOT the goal!

Planning VS Execution Conclusion:

Construction projects are complex in natural. Therefore, project team and planning team should cooperate to develop a realistic and workable plans. Planning team should be very fast and flexible to project conditions. Site team should understand the importance of the planning and it is in their benefit to against them. Whatever your experience is, if you do not have sufficient project management knowledge, you need to consider have some planning courses.