Deceleration according to a specific profile

I have received a design order for a deceleration system according to a specific profile (crash test system). The maximum load weight is 1500 kg, which is pushed towards the deceleration system and onto a rail with an initial speed of 80 km/h.
The acceleration profile is as shown below.

Question 1: How much acceleration frequency should I consider?
Question 2: Please guide me in choosing the size of the valve and cylinder.