Sir: Karachi is the fastest growing mega city in the world both in percentage and figure terms. Its population has been increasing day by day, but transport related problems have increased manifold in Karachi. Tens of thousands of public transport passengers are killed or injured every year in accidents. Many buses do not even have doors and windows that can be closed, and that only encourages passengers to ride by protruding from inside the vehicle or by hanging on from outside. Clearly, riding on the roofs or sides of buses and trains is inherently unsafe and results directly from the severe under capacity of public transport systems in Karachi. Government should take considerable liability for this major dilemma, and resolve the public transport problems at the earliest. GHANSHAM RATHORE Karachi