The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:

Given Data

• Train length = 130 m
• Train speed = 45 km/hr
• Time to cross the bridge = 30 s
• Required: bridge length

Step 1: Convert speed to m/s
45 km/hr = 45 × (5/18) = 12.5 m/s

Step 2: Total distance covered while crossing the bridge
Distance = speed × time = 12.5 × 30 = 375 mDistance = train length + bridge length ⇒ 375 = 130 + LL = 375 − 130 = 245 m

Checks & Common Pitfalls

• Add train and bridge lengths for complete crossing.
• Use km/hr → m/s conversion × 5/18.

Final Answer
The bridge length is 245 m.