The parish council has received two quotations for this work, which use different ways of achieving the desired result.
The first is for low mounds (about 60cm high), excavated from a trench immediately in front. There would also be 27 metal bollards installed, to show crossing points into the green and prevent illegal vehicular access. Lockable bollards would be used to enable authorised vehicles to enter. The price quoted is approximately £11,000.
The second is for 370 steel posts to be concreted into the ground, with 5 metal lockable drop-down bollards to enable authorised vehicles to enter. The price quoted is approximately £47,000.
It would be possible to adopt a combination of the above two approaches, which is likely to result in a cost somewhere between the two extremes. There is no point however in taking any action unless the whole green is protected.
In the question below another option given is to simply create a shallow ditch, instead of a ditch and mound (this is similar to the protective measures taken at the top of Brickhill Drive, by Foster's Brow).
No work would be carried out until after checking for any underground services, to ensure no damage is caused to cables or pipes.
The above quotations are the known costs so far. It is possible that other costs could emerge. The impact on the maintenance costs for Waveney Green are not known (e.g. grass cutting).