The Town and Country Tricycle.

This is the goal.
I want to build a trike that can be ridden safely in traffic, both slow moving and fast.
But hey, vehicle drivers cause the accidents? Right?
I had two accidents on my bike and both were caused by motorised vehicles. The first time was when I was approaching a junction to turn left onto a major road. A coach overtook me, so I stopped. When he turned left, he cut the corner and I ended up on the pavement. I was unhurt and the bike undamaged. The second time was crossing a motorway junction on an A road. As I neared my exit a van pulled out and hit me. It happened in slow motion. As I hit the side of the van I tried to push myself away but went over and the bike went under. I was bruised, cut jeans and hands but pretty superficial. The bike was not. Bent frame and wheel. I was lucky. It was a sunny morning and I was on the way to work. The driver couldn't see the bike as the sun was behind me. I felt sorry for guy, as he was more shaken up than I was.
There's actually a third time, but more of a near miss, and pretty much down to my own stupidity. Town traffic, two lanes in each direction. I signal, maneuver, etc and position myself to turn right through the two lanes of oncoming traffic. I get hit on the hip by a petrol cap cover that wasn't shut properly. My pride was hurt but nothing else. 40 mph zone.
One time I nearly hit a cyclist. I was turning left at traffic lights. I stopped and waited for the lights to change. When they did and I pulled off, I glanced left just before I turned. A cyclist had crept up beside me and was also moving. I was so close to have cleaned him of his bike.
Why do they do it?
I know people talk of the joy of melting through stationary traffic, but is it worth it?
I want one of those stickers for my car - "Cyclists are advised not to overtake this vehicle on the left hand side".
With a trike there's no temptation. You wait in line with everyone else.

Size is important. Being bigger means that you are more visible to other road users. Being wider gives a better road position. Too many times I have seen cyclists being squeezed out as cars, lorries, etc push past on a two lane road. As a cyclists it isn't pleasant going up a a hill with a lorry wheezing on your back wheel, but it's better than the vehicle passing when there's oncoming traffic, and the driver assuming that you're happy to move over and cycle up the hedge.

Visibility will be a major to the project.