Even before this latest little heat wave I was having heat related problems with the foam board infill on the new layout. The room the track is in faces south and although the track is behind closed curtains it still takes the full brunt of the sun on a clear day. I haven't had any problems with any of the other tracks here but then none have had solid infills.
The Artin track was just laid on the baseboard covering with grass scatter applied to the covering, this track is still there under the plywood cover and the visible parts seem ok. The Scalextric and Jouef track along with the first Airfix Monte Carlo track just sat on top of the plywood as did the previous Airfix layout and the last Monte layout. Both of these had some borders in place but the tracks all had room to move apart from the original Artin layout which ended up being glued to the baseboard covering bny the PVA used for the scatter.
I don't know if it's the foam board expanding, the track moving or a bit of both but there are problems with the foam board. In a lot of places the edge of the foam board has lifted above the track edge and most of the places that I added a small amount of filler this has come free from the track and foam board and fallen to the bottom of the gap.
A lot of the wider cars don't like the raised edges and it is even de-slotting some cars so with this in mind I need to find a solution. I did think about cutting the foam board back a little bit to leave a small gap and allow for expansion but as some of the cars, mainly the older Airfix and Jouef cars have very rounded profile tyres I'm not sure how well this would work.
Option two was to cut the foam board away and replace the plastic Airfix borders as at least they will move with the track if that is indeed the problem. Only problem with this is that I don't have enough borders and they are very hard to find and also Airfix never made any inner borders.
With option two in mind I have spent most of today experimenting with 3D printing some borders and they seem to be coming out quite good. Need to continue tweaking but we will see what happens tomorrow.