I'll throw this out for whatever its worth, it may or may not be a help with sleds
This was set up weekend at the kart track. For most of our exsistance like many other tracks we relied on hay bales as our saftey barriers.
About 7 years ago we tried to completely different aproch
The first thing we went to, and what may be an option for sleds was crash bags. Very simple, altho almost any size could be made, ours are 6 ft x 4 ft high. They are some type of urethane cover material sewn on 3 sides with a zipper on the forth. These are filled with scraps of foamm. They are a giant foam pillow.
Ours orginally came from a person making them in Mi. We paid $100. ber filled bag. That person is no longer around but we have found that any uporstery shop, or anyone with a good sewing maching can make up the covers. The foam he was getting was free, it was the cut off scraps from a materess company that they were paying to get rid of their scraps.
The foam itself never gets danaged and we simply have new bags made if they get ripped. Ours are bright red, yellow and blue for visability.
We commonly have karts ( 350-450 lbs with driver), go straight into these at 60-70 MPH very little injury, or damage to the karts, they simply wrap around you.
Our set up method for these is two rows of bags on high impact corners and a single row in less critical areas. Thes are spaced 3 ft or so away from our secondary barriers which line the track
The secondary barriers used to be hay bails. For years we would bag each bail in HD plastic bags to try to keep them dry ( light).
5 Years ago after looking at the cost per year we had on Bales we invested in Plastic inter-locking barriers. Our intial purchase was 40 K but we will brake even on this over a 10 year period and don't have to deal with al the work of puting out, picking up and constantly replacing the hay bales.
The plastic barriers have a 1/2 round end on one side and a concave end on the other so they can move together. They then use semi ratchet straps through the center and we hook them into 40 ft long sections.
When hit, they will move fairly easy at the point of impact, but slow you quickly because they must drag along 40 ft of barriers, kind of an accordian effect.
These two things used together has not only dramaticly cut down any injuries, it also stops most damage to the karts
Both of these are somewhat ajustable for different types of vehicles. Pillows can be made smaller or larger and filled with more or less foam. Barriers can be filled with either sand or water to any point to increase the amount of drag they have , or, you can simply make the chain longer.
The one draw back to these is transportation, their both very light, but they are bulky to transport
Altho these both are now common in karts and bikes, I have never seen it used with sleds and an just throwing the idea out there.
