I always read about large scale transformation or integration project that are total or almost total disaster. Even if they somehow manage to succeed  the cost and schedule blow out is enormous. What is the real reason behind large projects being more prone to failure. Can agile be used in these sort of projects or traditional approach is still the best.  One example from Australia is the Queensland Payroll project where they changed test success criteria to deliver the project.See some more failed projects in this SO question (on Wayback Machine)Have you got any personal experience to share?
Why do large IT projects tend to fail or have big cost/schedule overruns?
project management;project
The main reason is an increase in scope, which the book The Pragmatic Programmer describes as:feature bloatscreeping featurismrequirement creepIt is an aspect of the boiled-frog syndrome.The idea of the various agile method is to accelerate feedback and - hopefully - correct the evolution of the project in time.But the other reason is release management: if you aren't geared toward releasing the project (however imperfect it may be), chances are it will fail (because released too late, with too many buggy features, and harder to fix/update/upgrade).That does not mean you have to have a fixed release date, but that means you must be able at all time to build a running version of your program, in order to test/evaluate/release it.The blog post Late projects are late one day at a time contains many more examples:I know the Getting Real thing to do would be to Flex the scope and keep the launch date fixed, but that doesnt work if there is agreed upon functionality that cannot be completed in time.Thats why we dont advocate specs or agreed upon functionality. Thats the root of the problem  saying you know everything about what you need and how its going to be implemented even before the first pixel is painted or line of code is written.When you predict a rigid future on a flexible present youre in trouble. Rigid futures are among the most dangerous things. They dont leave room for discovery, emergence, and mistakes that open new doors.