Why do budgets of megaprojects increase by thousands of crores?

The additional budget of the megaprojects in the first eight months of this fiscal year is equivalent to twice the whole budget of the Padma Bridge.

Despite the prime minister's public scrutiny, almost all the government projects last year have increased.

Why do the budgets keep increasing? Why almost all of the time initial budget, the timeline of the project, and in some cases, the design turns out impractical?

Is this only due to lack of skills or is there any other reason behind it?

In Straight from Star Newsroom, Ahsan Habib and The Daily Star Deputy Planning Editor Wasim Bin Habib discuss the trend of budget increase of government projects in the country.