Yellow fasteners on concrete sleepers?

[83G/84D]

Can anyone explain what these are and what they are there for?

 

[YorkshireBear]

Was it on a curve?

 

[swt_passenger]

Lateral restraint anchors, aka lateral resistance plates. Most of it is out of sight, there’s vertical plates attached that you can think of like a small boat‘s keel. Helps retain the track position on curves.

There’s a few slightly different designs in use, the Unipart rail catalogue describes a couple here, one fits the middle of the sleeper and the other on the end: https://www.unipartrail.com/wp-content/uploads/2022/08/Lateral-Resistance-Plates.pdf

Benefits of Trackwork’s Lateral Resistance Plates:

Vertical ‘spades’ installed directly into compacted ballast provides increased stability and lateral resistance compared to alternative solutions.
Faster installation, with vertical ‘spades’ retro-fitted without the need for ballast excavation
Heavy Duty construction, eliminating the risk of deformation or buckling.

 

[83G/84D]

Was it on a curve?

Yes a slight curve.

Lateral restraint anchors, aka lateral resistance plates. Most of it is out of sight, there’s vertical plates attached that you can think of like a small boat‘s keel. Helps retain the track position on curves.

There’s a few slightly different designs in use, the Unipart rail catalogue describes a couple here, one fits the middle of the sleeper and the other on the end: https://www.unipartrail.com/wp-content/uploads/2022/08/Lateral-Resistance-Plates.pdf

Thanks for the explanation, it was really helpful.