This is why goods train seems longer than passenger train 

All of us have seen both goods and passenger trains. It always seems to us that a goods train is longer than a passenger train. But it is not so. 

Then why does it seem so? Let’s understand this. 

For this, we have to understand first the length of the platform and loop line. A platform has both loop lines and main lines. A loop line at the platform is a line that leaves the main line and rejoins it later. A loop line is used when a train standing on the main line is required to move from the main line. When such a situation arises?

Let’s assume that a train is standing on a particular platform. Later, another train is puffing into the station on the same platform. It is then; that the previous train standing on the main line is required to be moved onto the loop line so that the approaching train can come into the station. So, the length of the train should not be longer than the loop line or else it can’t be fully accommodated in the loop line and in that case, an accident is inevitable. 

In India, the standard length of a loop line is around 650 metres. So, the length of the train shouldn’t be more than 650 metres. 

Similarly, the length of the platform should be such that it can accommodate the entire train. 

When the length of a train should always be limited to 650 metres, then why do goods trains seem to be longer than passenger trains? 

While a passenger train has coaches, a goods train has wagons. The average length of a coach is around 25 meters. In order to be fitted into a 650-metre-long loop line, a passenger train will have a maximum of 24 coaches and an engine. 
On the other hand, a goods train has different types of wagons like BOX, BOXN and BOXN HL. Depending on the wagon type, the length of a wagon varies between 11 to 15 metres. 

In this case, in order to be fitted into a 650-metre-long loop line, a goods train will have 40 to 58 wagons as per the type of the wagon. 

So, when a passenger train can have a maximum of 58 wagons, a passenger train can have a maximum of 24 coaches. 

However, the lengths of a goods train and passenger train will vary not exceeding 650 metres, depending upon the number of wagons and coaches they have.