weights. Length of a truck, of a trailer, from axle to hitch point, kingpin to rear of trailer, and turning radius are all regulated. In additions, there are special rules for carrying containers, and countries can set their own rules for local traffic. The United States Federal Bridge Law deals with the relation between the gross weight of the truck, the number of axles, the weight on and the spacing between the axles that the truck can have on the Interstate highway system. Each State determines the maximum permissible vehicle, combination, and axle weight on state and local roads. Uniquely, the State of Michigan has a gross vehicle weight limit of , which is twice the U.S. federal limit. A measure to change the law was defeated in the Michigan Senate in 2019. Design Almost all trucks share a common construction: they are made of a chassis, a cab, an area for placing cargo or equipment, axles, suspension and roadwheels, an engine and a drivetrain. Pneumatic, hydraulic, water, and electrical systems may also be present. Many also tow one or more trailers or semi-trailers. Cab The "cab", or "cabin" is an enclosed space where the driver is seated. A "sleeper" is a compartment attached to or integral with the cab where the driver can rest while not driving, sometimes seen in semi-trailer trucks. There are several cab configurations: "Cab over engine" (COE) or "flat nose"; where the driver is seated above the front axle and the engine. This design is almost ubiquitous in Europe, where overall truck lengths are strictly regulated, and is widely used in the rest of the world. They were common in North American heavy-duty trucks but lost prominence when permitted length was extended in the early 1980s. Nevertheless, this design is still popular in North America among medium- and light-duty trucks. To reach the engine, the whole cab tilts forward, earning this design the name of "tilt-cab". This type of cab is especially suited to the delivery conditions in Europe where many roads require the short turning radius afforded by the shorter wheelbase of the cab over engine layout. "Conventional" cabs seated the driver behind the engine, as in most passenger cars or pickup trucks. Many new cabs are very streamlined, with a sloped hood (bonnet) and other features to lower drag. Conventional cabs are the most common in North America, Australia, and China, and are