A trailer bus is a type of mass transit vehicle that utilizes a semi-truck cab, but has a trailer made into seating for transporting passengers. Combining the flexibility and power of a truck with the comfort of buses, these vehicles were created in Europe nearly a century ago and remained popular for many years. Due to changing transportation needs and safety concerns, only one nation currently uses this form of a bus with any frequency.
The trailer bus was invented in the Netherlands in the 1920s. The bus' creation came out of necessity because conventional buses were being built very long to accommodate passengers, but frequently got stuck. When lengthy buses went over humped bridges, the central sections would grind against the road, stranding the bus. Trailer buses were put into production when it was discovered the independent passenger compartment provided more clearance space and did not catch on bridges.
The design was based on the articulated trailer, which was a type of bus that fused two cabin compartments together to create a single bus, much like how train cars were connected. This new bus had a semi-truck engine and cab, like the kind used to haul tractor trailers full of goods in the shipping industry. The rear was a converted trailer, outfitted to look and feel just like the cabin of a bus, but with the trailer connected at the truck's hitch.
For 50 years, from the 1930s to the 1980s, the trailer bus design was seen in use in many metropolitan areas. The trailer bus' cost benefits were one of the biggest reasons for its popularity. For example, on a traditional bus, if the engine breaks down, that bus would be inoperable until repairs were made. Likewise, if a bus' cabin grew outdated or also broke, the entire bus might need to be disposed of. The trailer bus, with its interchangeable parts, provided an efficient way to keep fleets of mass transit vehicles on the road.
During the 1980s, this form of transportation fell out of favor for many reasons. Chief among them was the improving quality of traditional bus designs. Safety concerns, however, also prompted this change, including worries about the trailer disconnections and the lengthy bus' inability to navigate tight turns. Havana, Cuba is currently the only major metropolitan area still known to use trailer buses for public transportation.