The defect that occurs due to warp in track is identified by measuring what?

The measurement of the difference in crosslevel is crucial in identifying defects caused by warp in the track. Crosslevel refers to the variation in elevation between opposite rails on a track and is indicative of how much the track may be tilted or warped. When warping occurs, it can lead to an uneven distribution of load across the rails, which affects train safety and comfort.

Monitoring the difference in crosslevel enables engineers to detect if one rail is higher or lower than its counterpart, which could signal issues such as track settling, wear, or maintenance needs. This measurement helps maintain the integrity of the railway infrastructure, ensuring a smooth and safe ride for trains.

In contrast, while the other choices could relate to different aspects of track conditions or maintenance concerns, they do not specifically focus on the warping effect that affects the cross-level of the rails directly.