Only done a couple of outdoor tracks - Daytona at MK, no tyres, and Silverstone, and they used very non moveable water filled 'barriers' - hit them resulted in a lot of pain
Went to a good one in Birmingham on a mate's stag do.
It was an interesting illustration of how much tyre heat matters. One of my engines failed (it was firing only when it got dragged up to speed by the other one on the main straight) and they pulled me in for a change of car. Set off with double the power and cold tyres. I squirmed a bit trying to get round the first corner but managed it without wiping out somehow!
Kevin
Every time I do Daytona, similar issues. You do 10 mins of warm up/qualifying, then sit at standstill for 10 mins whilst they get cars in order. Its a rolling start, but even so, still cant get enough heat in. 2nd corner (1st is an easy flat out 90 degree left), every bloody time