The Signal de Bougy park can be reached by foot or by bike from Allaman station.
Beware: the last stretch between Bougy Villars and Signal de Bougy is quite steep.
It is possible to come by bike (except for a short stretch towards Féchy, where there are a few steps).
Find the trail here.
There is another trail that takes you close to the Adventure Park.
You can download it here.
More information: Morges Région Tourisme