(a) Importance of waterways is declining because : 

(i) It is a slow means of transport. 

(ii) Rivers of India do not have a regular flow of water as water is diverted for irrigation. 

(b) Helicopter services may be used in : 

(i) Mountains 

(ii) Flooded areas. 

(c) Problems faced by Indian railways are :

 (i) It lack repair and maintenance of tracks and bridges. 

(ii) India as the railways operation is on their gauges and shift from gauge to another is a problem. 

(iii) Rail traffic has increased and the old tracks are not able to carry the increased load and accidents are frequent. 

(d) Golden Quadrilateral comprises the national highways connecting Delhi-MumbaiChennai-Kolkata by a 6-lane super highway. It has a total length of 5846 km. Two ways it will help in the economic development of the country are : 

(i) India is a land of vast distances from north-south as well as from east-west. This forms an integrated transport system and bring different people together. 

(ii) Cities lying close to these roads will also be well developed and enhance the growth of our country.