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Six Sigma Tollgates Provide a Reliable, Logical Way to Approach Process Improvement

Six Sigma Tollgates Provide a Reliable, Logical Way to Approach Process Improvement

DMAIC process concept

Last Updated March 8, 2024

In Six Sigma, every project comes with tollgates that act as milestones marking the pathway to success. They provide guidance for project teams, keeping them on track, within the project scope and focused on the desired outcome.

Each of the five phases in the Six Sigma strategy, DMAIC, have three tollgates each. Teams complete each tollgate before moving on to the next phase. As students in Villanova University’s Lean Six Sigma Black Belt course learn, each tollgate is equal in importance. Making sure they are completed requires a process called tollgate review.

“Tollgate reviews are specific steps that must be done sequentially during each phase of a Six Sigma project. They ensure that nothing will be skipped and are key to the successful completion of the project,” said Marv Meissner, MBA, Professor of the Practice in Villanova’s Certificate in Lean Six Sigma program.

How to Manage Tollgate Reviews

Organizations have multiple options when it comes to how to handle tollgate reviews while following DMAIC methodology, an acronym that stands for Define, Measure, Analyze, Improve and Control. The fivephase process provides a framework for project teams to follow as they analyze current operations and develop changes to make them more effective and efficient.

Some companies may hold a long meeting at the completion of each DMAIC phase. Others may hold shorter meetings after the completion of each individual tollgate.

Whichever way is chosen, the idea behind tollgate reviews is to ensure each tollgate is completed successfully. Every detail is considered. Since DMAIC builds upon what is done in each phase, teams must take care in making sure each tollgate is complete.

In Villanova’s Lean Six Sigma Black Belt course, students are encouraged to hold a review after each tollgate. Meissner said doing so carries the following advantages.

  • Project sponsors get the chance to review each step of the project, saving time and preventing re-work
  • The discussion focuses on just one, specific tollgate
  • Teams can more easily schedule shorter meetings
  • Frequent meetings keep the sponsor actively engaged

The invitation list to the meetings should include Green Belts, a Black Belt mentor, the project sponsor or champion, and the appropriate project team members.

How to Prepare for a Tollgate Meeting

Preparation is key to a successful tollgate meeting. Team leaders should follow guidelines to ensure a tollgate meeting is effective.

  • Send documentation to the project sponsor days before the meeting for review
  • Determine the best format for the discussion and set an agenda in advance
  • Include time to update attendees on changes to the charter, scope, team members, etc.
  • If meeting via phone or internet, ensure everyone has the correct connection information 
  • If using software, make sure that it is compatible for everyone
  • Remind the sponsor which tollgate or tollgates are being reviewed
  • Review prior phases and/or tollgates and then briefly review the current information, including the tools used and findings
  • Request approval to move to the next tollgate or revisit a prior tollgate if needed
  • Request additional resources if appropriate. If approved, let the sponsor know what the next tollgate and goals will be

As for the project sponsor, they also have specific duties to keep in mind. “The sponsor’s responsibility during a tollgate meeting is to provide guidance, insights, and suggestions,” said Meissner.

Additionally, the sponsor should update the team on broader level issues they may not know about, ensure the project remains within scope and makes progress toward the project goal. Sponsors also provide resource support, including staff and funding, and have the responsibility to stop a project if it is no longer viable.

The 15 Six Sigma Tollgates

Each phase of DMAIC has three tollgates. Here’s a brief overview of each, as taught in the Lean Six Sigma Black Belt course.

Define Phase Tollgates

  1. Create the project charter – The charter provides a clear and concise summary on key information about a project. It includes a business case for the project, a problem statement, and project scope.
  2. Voice of customer – This identifies the customers of the product or service that results from the process under review. Teams also define the needs and requirements of customers.
  3. Map the process – Specify the steps taken to deliver a product or service.


Measure Phase Tollgates

  1. Performance indicator identification – Specify what needs to be measured with a focus on leading measures that are upstream in the process.
  2. Data collection plan – This makes it clear how data will be collected and sets down definitions and procedures.
  3. Baseline performance measurement – This provides an evaluation of how the company’s current process is performing. Later, this will be compared to what happens after improvements are made.

Analyze Phase Tollgates

  1. Potential root cause – Teams identify anything that might contribute to the problem by brainstorming as many root causes as possible. Nothing should be left out. 
  2. Narrow root causes – Teams identify the root causes that most likely act as the largest contributors to the problem. 
  3. Critical root cause – This cuts the root cause list down to the critical few that, if eliminated or reduced, will make the biggest positive impact on a process.

Improve Phase Tollgates

  1. Generate possible solutions – The team reviews all possible solutions to each of the critical root causes.
  2. Select solutions – The team selects the best solutions based on what is the most important to the customer, the company and the project. Data will drive this decision.
  3. Implement solutions – The team puts the solution into place through an implementation plan that outlines when it will be implemented and any requirements for resources.

Control Phase Tollgates

  1. Monitor and control plan – The team creates a plan that sets up how to continue to measure performance of the solutions and ensure new processes and procedures are executed correctly.
  2. Response plan – The team creates a plan to address potential problems that may arise.
  3. Continual improvement plan – Continual improvement is a core concept of quality. All projects require a final tollgate that creates a plan to continue making improvements to the process in the future.

This logical, clear process provides detailed steps on how to successfully create and complete a project. It’s a process that is reliable and repeatable, giving teams a way to approach process improvements in any project.