Constructing a 1,850 km major pipeline in a limited time period is a significant challenge in itself, but this task gets much more difficult if the project is crossing many different challenging climatic and topographical areas, i.e. facing challenges during construction.

Major challenges and risks of Mega Projects can be summarised as:

• Economic and political instability: market volatility
• Cost & schedule pressure
• Project governance complex: decision-making, ownership, financing, client-contractor relations, stakeholder alignment, ethics & compliance
• Project resources scarcity & competency
• Technical challenges: tight specs, harsh design conditions and late design
• changes,
• Construction challenges: climatic and topographical conditions
• Health and safety, social and environmental challenges
• Variable performance from PMCs, contractors, & vendors 

Among other challenges and risks, this paper will concentrate more on construction challenges. Construction of the Trans Anatolian Pipeline (TANAP) through Turkey has been completed as planned and well below the budget, overcoming most of the above challenges among which climatic and topographical conditions were probably the most important ones requiring careful planning and implementation at site.