NEC: An introduction to ‘Acceleration’

What is Acceleration?

Acceleration is the process of bringing forward Completion or Key Dates compared to the Accepted Programme. It involves changing how the works are carried out to finish earlier than originally planned.

• Typically includes:
  • More labour or longer working hours
  • Additional plant or resources
  • Resequencing activities
  • Working less efficiently to gain time

Acceleration is Triggered via Clause 36 of the NEC ECC.

• The Project Manager (PM) initiates the process
• The PM instructs the Contractor to provide a quotation for acceleration
• The Contractor must submit:
  • Revised programme showing earlier completion
  • Methodology changes
  • Cost of achieving acceleration

What is the Contractor’s Position?

• The Contractor is not obliged to accelerate
• They are only required to:
  • Provide a quotation when instructed

What Happens After the Quotation?

• The Project Manager can:
  • Accept the quotation → acceleration proceeds
  • Reject it leading to no acceleration
  • Request a revised quotation
• If accepted:
  • It becomes a compensation event
  • Prices are increased
  • And Completion Date is brought forward

Acceleration vs Mitigation – is an important distinction

• Mitigation
  • Contractor’s obligation to reduce delay impact
  • Usually no additional payment
• Acceleration
  • A deliberate instruction or agreement to finish earlier
  • Contractor is paid for additional cost

Commercial Considerations

• Acceleration is often used where:
  • The Client benefits from early completion (e.g. revenue, access, avoiding penalties)
• Key risks:
  • Contractor accelerates without formal agreement → may not recover costs
  • Poorly defined scope → disputes over what was included
• Best practice:
  • Is to ensure clear instruction, quotation, and acceptance before starting

Practical Examples include:

• Working weekends or night shifts
• Increasing crew sizes
• Bringing forward design or procurement activities
• Overlapping activities that were originally sequential

Key Takeaway‘s

• Acceleration under NEC4 ECC is:
  • Optional
  • Client-driven
  • Commercially agreed
• It must be properly instructed and accepted to ensure:
  • Time and cost are both adjusted fairly