The culprit is a molecule called gliadin, which is found in certain gluten-containing grains and causes symptoms in gluten-sensitive people. The grains that cause the greatest problems are wheat, rye, barley, spelt, and kamut; whereas corn, rice, millet, and buckwheat are generally considered safe.
The Forth Bridge's piers are constructed from 120,000 cubic yards of concrete and masonry, faced with 2 ft thick granite. 200 trains use the bridge every day, carrying 3 million passengers each year. The total painted area of the Forth Bridge is 230,000 sq metres, requiring 240,000 litres of paint.
Wooden beam bridge A beam bridge is a strong, horizontal structure that rests on two end supports, and carries traffic by acting as a beam. Beam bridges are often used for heavy cars and trains to pass, and some are also built for people to walk on. Beam bridges used to be made from wood and were called log bridges. Modern ones are mostly made of steel. Beam bridges are usually placed over highways or gaps in the earth so people or cars can cross over them.