What's around the bend?

This bridge at Hollin Hey in St Helens comprises two Skew type bridges. Because they are not square to the road below, half of each portal would be weak and prone to collapse. Their unusual style of bricklaying provides two interesting solutions to the structural problem.
The Western half of the bridge employs courses of Logarithmic brickwork of differing heights while the eastern half employs the more economic use of regular bricks which are laid along inclined courses and known as Helicoidal brickwork.