So, my idea is to address the potential issue of pram safety... there are a few requirements around this that I want to include.

1\ Low cost to implement

2\ Modular to be used / installed on many different prams

3\ Easy to install and use... intuitive learning curve

4\ low chance of failure

5\ easy to reset

6\ reliable trigger

With these things in mind I have sketched a few options on how the mechanism will work.

Stopping Mechanism

This component is key to the success of the device.. how should the pram be stopped... should this be an abrupt stop or a gradual slow down? My thoughts on this are that it should be a swift and decisive stop of the pram... the reason behind this is that there may be minimal distance that the pram would travel before it (and the occupant) is in imminent danger... such as a train track. The sooner it stops moving the better.

This line of thinking gives rise to a couple of stopping mechanics that might be appropriate. The thing to consider here is where to apply that stopping force? How would you stop a moving object that has wheels? 

An anchor of some sort to adhere to the ground... like a spiderman web!? This would be good as a one shot... but it isn’t a good idea for multiple uses. Costly as a result and cumbersome to re-load.

A mechanism that lifts the pram wheels off the ground to stop any further wheel based movement... replacing the bottom with a set of stilts (not high.. perhaps only lifting the wheel about 1 - 2 cm off the ground) or a box like object to lift the pram up. This could cause instability in the overall pram... although the wheels would only be lifted off the ground enough to stop them adhering to the ground.. it would need a way to reset all the wheels. This may not be practical for larger wheeled prams. This option may also have problems depending on which way the pram is moving.

Applying a brake directly to the wheel like a traditional bicycle.. this seems to be the most logical option as it has the widest application across multiple pram wheel sizes. The brake would be applied directly to the tyre surface using a spring loaded mechanism.. much like a peg.