The theory of constraints is an important tool for improving process flows. The implications of the theory are far-reaching in terms of understanding bottlenecks to a process and better managing these bottlenecks to create an efficient process flow.

The theory of constraints is an important tool for operations managers to manage bottlenecks and improve process flows. Made famous by Eliyahu M. Goldratt in his book The Goal, the implications of the theory are far-reaching in terms of understanding bottlenecks to a process and better managing these bottlenecks to create an efficient process flow. Simply put the theory states, “the throughput of any system is determined by one constraint (bottleneck).” Thus, to increase the throughput, one must focus on identifying and improving the bottleneck or constraint.

Goldratt in another book, Theory of Constraints, outlines a five-step process to applying the theory:

1. Identify the process’ constraints

2. Decide how best to exploit the process constraints

3. Subordinate everything else to the above decisions

4. Evaluate the process constraint

5. Remove the constraint and re-evaluate the process


Long queues could be very frustrating in any bank and much more in Nigeria. Most times one must wait for more than 30 minutes  at the bank to withdraw money from the Automated Teller Machine (ATM) and this affects some other schedules for the day. During my last Holidays, while I was in the queue in one of the Banks in Nigeria, I made some useful observation which I thought could help our people and Banks especially in reducing the waste arising from long wait times at the ATM. On average, it takes 47 seconds to 1 minute of a single withdrawal, to withdraw money from the ATM in the US. Long queues build-up when customers do not follow the best practices or are not considerate of others and this could be seen here as excess inventory which slows efficiency of the ATM Banking system and which has a potential effect on other banking departments. So, this post offers some principles and ideas from “the goal” that could be applied to minimize and/or eliminate long wait times to make ATM transactions more efficient.


 To decongest long queues at the ATM to ensure customer satisfaction.


The major constraints identified in the process is poor customer attitude and occasionally, poor Internet service or machine downtime.  The constraints are observed in the following practice wrong practices:

1. Many who come to the ATM to transfer money and pay bills and struggle with their phones to retrieve information for the transaction.

2. Many come to activate their debit card Pins and spent time thinking on the new password to use.

3. Many elderly men and women with no knowledge of ATM operation, seek help from people around to carry out their transaction when it is their turn to use the ATM, this leads to waste of valuable time

4. Many come with cards that are worn out or bent because of misuse, and the machine keeps rejecting the card, while they keep trying.

 5. Problems arising from unstable Networks at the ATM (Out-of-service error display).

             Having identified the constraints, we shall apply the theory of constraints to improve the process.


Exploit the identified constraints ( bottlenecks) by  Customer re-orientation/ Education through mails and adverts. Improved banking services.


Every other Customer coming to the bank must be informed to comply with the best practices at the ATM, and the customer care must ensure compliance and offer support at all time to customers that need help.


 The following actions are necessary to eliminate the constraints:

 1. Self-service machines designated for other banking services other than withdrawing money and for the disabled. 

2. Queuing up in a row at the ATM helps minimize chaos and maintain a steady flow. 

3. Transaction details if not memorized,  should be copied out in a paper or ready on the phone when going to the ATM.

4. Withdrawals must be made in bulks(pre-set) or own the desired amount, to reduce the number of withdrawal cycle.

5. Counting money after withdrawal from the ATM should be avoided. The ATM is error proof.

6. Checking balances after withdrawal should be avoided.

7. Multiple card removal and insertion in a transaction must be avoided.

8. More education in using e-banking services can decongest long queues at the ATM. Why go to the ATM to pay bills, buy airtime or even make transfers when you can log into your mobile app or dial some code to carry it out at the comfort of your home? 95% of Nigerians who go to the ATM, go to Withdraw money so this should be given priority.


1. Provision of designated E-service ATM machines inside the banks or any secure place outside the bank to enable customers who come to the bank for any other business other than withdrawing money, like fund transfers and bills payments.

2. Improved ATM functionality by increasing internet bandwidth and preventive maintenance on the ATM to avoid long downtime.

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