designed for the delivery of fresh milk. A new form of delivery is emerging on the horizon of the internet age: Delivery by the crowd e.g. crowd delivery. In this concept, an individual not necessarily contracted by the vendor performs the delivery of goods to the destination. Sometimes, private courier companies will also deliver consumer goods on a regular basis for companies like E-commerce businesses. In the 2010s and 2020s, a number of companies started using gig workers driving their own vehicles rather than permanent employees driving company vehicles to make deliveries of groceries, food, and general retail items. Drivers typically sign up and get work assignments using a smartphone app. Arrangements range from producers and deliveries made by separate companies (such as with Uber Eats, DoorDash and GrubHub) to in-house deliveries only (such as Amazon Flex, although Amazon also uses contracted delivery companies in Amazon-branded vehicles), to a mixture (such as Walmart Spark, which delivers both Walmart and third-party products). Delivery vehicles The consumer demand for supermarkets to deliver to their door created the need for a mixed temperature controlled vehicle on 3.5T chassis. These vehicle bodies were initially built with the traditional GRP sandwich panels but as more damage resistant lightweight materials with better insulation properties have become available companies have been developing Advanced Home Delivery Vehicles. The 2012 Commercial Vehicle Show in the UK saw the new JDC PolyBilt design, one of the latest of these "Plastic" bodies that can be recycled at the end of its service life, unlike the traditional GRP which ends up as landfill. Vehicles are often specialized to deliver different types of goods. On land, semi-trailers are outfitted with various trailers such as box trailers, flatbeds, car carriers, tanks and other specialized trailers, while railroad trains include similarly specialized cars. Armored cars, dump trucks and concrete mixers are examples of vehicles specialized for delivery of specific types of goods. On the sea, merchant ships come in various forms, such as cargo ships, oil tankers and fishing boats. Freight aircraft are used to deliver cargo. Often, passenger vehicles are used for delivery of goods. These include buses, vans, pick-ups, cars (e.g., for mail or pizza delivery), motorcycles and bicycles (e.g., for newspaper delivery). A significant amount of freight is carried in the cargo holds of passenger ships and aircraft. Everyday travelers, known as a casual courier, can also be used to deliver goods.