Cattle grid-like plate question

[Littlecheez17]

I have wondered this for a while now, what is the cattle gird like object in the middle of the track for? I usually see this where signals are placed, like shown in this image here, from network rail (top of page). Network rail Image
I have also seen this at some places that aren’t near signals. Does anyone know what this is, i would be grateful for any reply’s.

 

[cin88]

Its part of the Train Protection and Warning System. They cause equipment on a train to apply the emergency brakes if the train passes the signal at danger without authority.

The ones not near signals are on the approach to significant reductions in line speed. They'll apply the emergency brakes if a train hasn't slowed down enough where there's a lower speed limit coming up.

 

[MadMac]

I have wondered this for a while now, what is the cattle gird like object in the middle of the track for? I usually see this where signals are placed, like shown in this image here, from network rail (top of page). Network rail Image
I have also seen this at some places that aren’t near signals. Does anyone know what this is, i would be grateful for any reply’s.

TPWS grid. The ones you see that aren’t at signals are to determine speed on the approach (overspeed sensors) to a signal and then activate the onboard system: that system will “intervene“ if no action is taken by the driver.

 

[GC class B1]

Its part of the Train Protection and Warning System. They cause equipment on a train to apply the emergency brakes if the train passes the signal at danger without authority.

The ones not near signals are on the approach to significant reductions in line speed. They'll apply the emergency brakes if a train hasn't slowed down enough where there's a lower speed limit coming up.

It is not correct to say that TPWS applies the emergency brakes as there aren’t any emergency brakes, there is only one service braking system on British rolling stock. TPWS initiates an emergency brake application of the service brake. This is the same as an Emergency brake application initiated by the driver and on modern Multiple Units it is a greater deceleration rate than the Full Service brake application. On locomotive hauled freight and passenger trains the deceleration rate is the same in both Full Service and Emergency brake applications.

 

[Nottingham59]

I have wondered this for a while now, what is the cattle gird like object in the middle of the track for? I usually see this where signals are placed, like shown in this image here, from network rail (top of page). Network rail Image
I have also seen this at some places that aren’t near signals. Does anyone know what this is, i would be grateful for any reply’s.

Welcome to the forum!
You might find these links helpful in explaining how TPWS operates

Train Protection & Warning System - Wikipedia

en.wikipedia.org

Train Protection & Warning System (TPWS) Basic Concept – Railway Signalling Concepts

 

[Annetts key]

I have wondered this for a while now, what is the cattle gird like object in the middle of the track for? I usually see this where signals are placed, like shown in this image here, from network rail (top of page). Network rail Image
I have also seen this at some places that aren’t near signals. Does anyone know what this is, i would be grateful for any reply’s.

The items that you are referring to are part of the TPWS (Train Protection and Warning System). Officially they are called loops, as within them there are coils of wire in a ‘circular’ loop.

But are also known by various other names, such a grids, toast racks and trampolines.

The loops are always fitted in pairs. But depending on the exact use, they may not be immediately next to one another.

They are fitted adjacent to signals where there is a point of conflict ahead (beyond) the signal such as points, a junction, a level crossing or where it has been deemed to be otherwise required. Hence not all signals are fitted in plain line areas. These are called TSS (Train Stop System).

They are also fitted on the approach to (in rear of) signals where the loops fitted at the signal do not provide sufficient braking distance before the train would reach the point of conflict. These are known as the OSS (Overspeed Sensor System).

The above two systems when combined are effective for train speeds up to 75MPH.

On faster lines, TPWS+ may be fitted. Here an additional OSS (known as a OSS+) is fitted further back than the normal OSS (typically 750 metres from the signal). Hence will bring a train to a low speed before the point of conflict. TPWS+ is effective up to 100MPH.

TPWS is also fitted on the approach to buffer stops. This is just a OSS. However, the loops may be a smaller type compared to the standard size.

TPWS may also be fitted on approach to some permanent speed restrictions. Again, it’s an OSS.

If a temporary speed restriction is going to be in place for an extended amount of time, this may also be provided with a TPWS OSS if deemed necessary.

TPWS is not as good as Automatic Train Protection (ATP) or systems that incorporate ATP such as ERTMS (European Rail Traffic Management System) / ETCS (European Train Control System).