What approach do you take to managing complexity in projects?

Five important strategies, both conventional and adaptive, to deliver the solution on large, long, high-cost projects are presented:

1. Iteration is the best defense against uncertainty
2. Scope minimization is the key to success
3. Last responsible moment decision making keeps your options open
4. Rapid application development reduces time to market
5. Lean development techniques increase efficiencies

Planning, Excution, Monitoring

A good approach for reducing the complexity of any project is dividing it into parts that you already know and you can easily manage. The more complex is the project, the more important is to develop a good WBS.

Good question. Thank you.

Very good question

Agreed with both answers given by Mr.: Fouad ahmed & Mr.: Ramy zakher as well too

Good question. and i agree with mr Fouad. 

More simply. If you want to manage a complexe project. You must divided it to many department to control the work and also a risk. 

I big and complexe project we always divided it to two or three small project. 

Complexities, Risks and Uncertainties are a part & parcel of projects and are inherent by the very nature of projects which is defined as "A temporary endeavour to achieve a unique product or service". The2 words Temporary & Unique is the reason behind these.

My approach to manage projects is to adopt to the policies, processes, procedures, tools & technique and code of conduct as prescribed by PMI in their PMBOK as it increases the probability of success in projects. 

#1: Define the project

As the project manager, you must make sure that the work is properly understood and agreed to by the project sponsor and key stakeholders before the project work begins.

#2: Plan the work

When you define the project, you make sure that you have an agreement with the project sponsor on what work should be completed in this project. In this stage, you determine how the work will be completed. This involves building the Project Work plan. You'll take different approaches according to the size of the project. For example, the work plan for small projects can be built using a project management package like Microsoft Project, a spreadsheet, or even a piece of paper.

#3: Manage the work plan

At this point, you've finished defining the project and planning the work. The major deliverables in place are the Project Definition and Project Work plan. Some project managers think that defining and planning the work means that the hard part of managing the project is behind them. That is definitely not the case.

#4: Manage issues

An "issue" arises when a problem will impede the progress of the project and can't be resolved by the project manager and project team without outside help. If a major problem emerges, you have no choice but to resolve it. The only question is whether you'll actively apply issues management to the situation or flounder through indecision and uncertainty about how the issue should be resolved.

#5: Manage scope

Scope describes the boundaries of the project and defines what the project will deliver, what data is needed, and which organizations are affected. Given a set of resources and time, an infinite number of things can be delivered.

#6: Manage risk

Risk refers to future conditions or circumstances that exist outside the control of the project team and that will have an adverse impact on the project if they occur. In other words, whereas an issue is a current problem that must be dealt with, a risk is a potential problem. Reactive project managers resolve issues when they arise. Proactive project managers try to identify and resolve potential problems before they occur. This is the science and art of risk management.

#7: Manage communication

Properly communicating on a project is critical for managing the clients and the shareholders. If they're not kept well informed of the project progress, there is a much greater chance of problems and difficulties due to differing expectation levels. In fact, in many cases when conflicts arise, it's not because of the actual problem, but because the client or manager was surprised.

#8: Manage documents

Many project managers take document management for granted until they're inundated with hundreds of documents. It's better to estimate the volume of project and project management documentation you think the project will produce, establish the proper processes and rules to organize the documentation, and then manage the documentation during the project to ensure that it doesn't get out of control.

#9: Manage quality

Quality is represented by how close the project and deliverables come to meeting the client's requirements and expectations. In other words, quality is ultimately measured by the client.

#10: Manage metrics

Managing metrics and managing quality are related. It is difficult to improve the quality of your deliverables or your processes if you're not gathering metrics. Metrics are used to give some indication of what the beginning state of quality is and whether quality is increasing or decreasing.

In large project you need to creat plan for managing project policies and processes in order to solve any complexity  may face you in the future.

In general you'll need to focus on10 processes 

Define the project

Plan the work

Manage the workplan

Manage issues

Manage scope

Manage risks

Manage communication

Manage documentation

Manage quality

Manage metrics

Of the various elements that combine to make long-duration projects complex, the most significant is the inevitable changes that will occur in the business environment, which will necessitate adjustments to virtually all elements of the project. Knowing this, the successful project leadership team evolves, practicing situational project leadership, adapting and modifying their approach to accommodate the inevitable changes. In addition to adapting to change, the sheer size of the work involved for large projects weighs heavy on the project team. Research has demonstrated that the smaller the project team and the fewer deliverables, the greater the likelihood of project success. Therefore, the project leadership teams need to reduce the size of work packages to "seem like" many small projects, as opposed to one very large endeavor. As a final point, team fatigue and burnout lead to complex human interactions and unavoidable staff turnover, both of which are difficult to predict and manage.

MANAGING THE COMPLEXITIES OF LARGE, LONG, HIGH-COST PROJECTS

The complexities of large projects require that particular attention be directed to planning the project, developing and delivering the solution, selecting team members, and sustaining a high-performing team over the long haul.

PLANNING THE PROJECT

Six important strategies for planning and structuring large, long, high-cost projects are offered, both conventional and adaptive in nature:

Adaptive management approaches complement traditional practices

Progressive elaboration allows the project to evolve

A systematic, reliable approach to estimating increases confidence and accuracy

Rigorous time and cost management increases reliability

Stage-gate management enables continuous improvement

Rigorous risk management pre-empts challenges and seizes new opportunities

1. ADAPTIVE MANAGEMENT APPROACHES COMPLEMENT TRADITIONAL PRACTICES

For large projects, the ability to adapt is the difference between success and failure. The leadership team should analyze the situation, correctly answering questions like: Is this really a program? Is it a series of modestly scoped, small projects? Must the project or program deliver a product line, a system of systems? Can the solution be delivered in components? Only after this analysis should management decisions be made. In particular for long-duration projects, success depends on selecting the management approach best suited to deal with the changes that will inevitably occur. The team strives to recognize the nature of the problem and solution, and to understand whether the conventional, reductionist systems/software engineering and project management approaches will work effectively. Only then can we make the right choice of management approaches (e.g., conventional vs. adaptive techniques, appropriate project cycles, the best project team structure). It is also prudent to build continuous customer and end-user evaluation and feedback into the approach to ensure that the project delivers what is needed-which often is not what was originally proposed for large, long-duration projects.[i]

2. PROGRESSIVE ELABORATION ALLOWS THE PROJECT TO EVOLVE AND THE SOLUTION TO EMERGE

Continuously improve and add detail to the project approach as more information becomes available. Allow more accurate and complete plans to emerge from the successive iterations of the planning process. Instead of trying to plan the entire project, start by scheduling only the activities that define firm basic requirements.[ii] Then, begin to plan activities to develop a conceptual design of the solution at a high level, resisting design decisions that will impose constraints.

3. A SYSTEMATIC, RELIABLE APPROACH TO ESTIMATING INCREASES CONFIDENCE AND ACCURACY

Estimating is hard, very hard. One precondition to being assigned as manager of a complex project should be a track record of developing reliable estimates. To increase reliability, use multiple estimating techniques. Educate your project sponsor and other key stakeholders about the fallibility of estimates in general and discuss the reliability they can expect from your specific estimates at key points in the project. Without a doubt, early estimates will be highly unreliable, exhibiting a wide range of variability. Numerous uncertainties are involved when building something unique with a team that has not worked together in the past. However, once the project has executed through a few iterations (if using incremental techniques) or through a few project phases (if using linear techniques), you can begin to gauge the speed of progress and adjust your original estimates accordingly.

4. RIGOROUS TIME AND COST MANAGEMENT INCREASES RELIABILITY

Delivering on schedule is one of the main challenges for a long-duration project, simply because of the enormous amount of work to be accomplished. Implement a rigorous process for tracking progress and controlling output. Track progress to the next milestone or release scrupulously. Manage the schedule and budget by establishing a project support team to update and maintain the schedule and budget baselines; emphasize to team members that they should bring any issues that put the next milestone/release in jeopardy to your attention immediately.

5. STAGE-GATE MANAGEMENT ENABLES CONTINUOUS IMPROVEMENT

Stage-gate management can be used to create opportunities to gather feedback from your customers and your team members on a frequent basis. After completing each phase, iteration, or release, conduct informal team-based quality reviews of deliverables. As part of these reviews, determine what worked well and identify opportunities for improvement to the solution development process and team operations. Subsequently, conduct a formal external quality assurance review of major deliverables and incorporate actions to correct defects found in the deliverables that must be resolved before work can proceed. Update the project cost, schedule, and scope baselines for the remaining near-term project phases/iterations, incorporating lessons learned into the plans. As part of the review process, examine the business case to validate that business benefits will be achieved and the investment is still sound. Conduct a formal project review with the project sponsor and other key stakeholders to secure approval to formally launch and expend funds for the next phase/iteration.

6. RIGOROUS RISK MANAGEMENT PRE-EMPTS CHALLENGES AND SEIZES NEW OPPORTUNITIES

Few projects perform adequate risk management. For large, long-duration projects, it is essential to identify risks after each iteration/phase and re-examine risk responses to:

Ensure the risk response plans are managing known risks

Identify new risks and develop risk response plans

Identify new project dependencies and interrelationships and develop dependency management plans

Identify previously unknown opportunities to increase the business value of the solution

DEVELOPING AND DELIVERING THE SOLUTION

Five important strategies, both conventional and adaptive, to deliver the solution on large, long, high-cost projects are presented:

Iteration is the best defense against uncertainty

Scope minimization is the key to success

Last responsible moment decision making keeps your options open

Rapid application development reduces time to market

Lean development techniques increase efficiencies

Several Gentlemen have posted very good answers!

I do have to agree with Mr. Hossam Assam mentioning in his post agreeing with answer from Mr. Fouad Ahmed and Mr. Ramy Zakher.

My own experience working and seeing Project Management at work in a large Pharmaceutical Company are:

Seeing a project divided into multiple managers with various responsibilities to keep the projects organized; in compliance with environmental issues; on time and in competent hands to succeed.  

I have been working for3 Project Managers at one point assigned to the same project.

1)     Executive Project Manager which monitored the progress of the Team Leader

2)     Team Leader and his team of12 Engineers each having a current and several projects to monitor;

3)     The Project Manager I primarily assisted had7 projects, with minimal supervision required and2 high visible projects and there Production Managers.

We ordered the equipment, monitored the planning stage, approving building plans and coordinated with the department which handled the construction crew and contractors to insure in time and correct construction of the building.  This simple structure allowed an in time operational facility, which had a high dollar value to be built in a relative short time frame and a high security demand, due to usage of genetic materials used in the production

you need to break down complex project to sub project and connect them.