Awkward speed bumps

Two winters ago while riding my motorcycle to work at 5 am on a road with a skimming of snow I approached a speed bump which was invisible because of the snow.

I was travelling at approximately 10 mph. The speed bump was one of those square ones with sloping sides.

Unluckily I rode over the side of the bump which slopes to the side. This made the wheel slide sideways and subsequently I fell off the bike and the bike fell onto its side.

The front indicator was smashed and I received a few bruises.

As the bike is quite heavy and the road was slippy I found it impossible to lift my bike back onto its wheels.

Fortunately 2 men in a van stopped and helped me to stand the bike up. I then proceeded on the way to my workplace.

If speed bumps were all made in a line accross the road I would never have fallen off.

Has anybody else had similar problems with these bumps or am I just unlucky?