Investing in radios?

I'm debating whether to buy some 2-way radios for the family, mainly for the kids. 

Me and my husband are working the rest of the summer holidays so the children are either at my parents or home alone. I'm trusting my eldest, who is autistic, to look after her brother, who's 8, whilst I'm at work for a few hours down the road so I'm around if they need me. If I buy radios, it will be myself and my 2 daughters using them. They are planning days out by themselves so it will be easy to contact me via radio, quick and easy. Also my eldest takes my son out down the road quite a bit now so she will always have one on her so can contact home without using her phone so her full concentration is on my son and the road and cars and the people around aswell. 

Do you think it will be worth it?