both a bucket-wheel excavator and a stacker in appearance. They are identifiable by their long discharge boom which can range as long as 195 meters in length. Stackers Stackers are mining vehicles that exclusively run on rails and are imposing in size, with some stacker-reclaimer hybrids having a boom length of 25 to 60 meters. These vehicles may resemble a spreader, however, a stacker's role is to pile bulk material onto a stockpile so that a reclaimer could collect and redistribute the materials. Stackers, therefore, often work in conjunction with reclaimers. Reclaimers Reclaimers are mining vehicles that, like stackers, run exclusively on rails. Reclaimers are traditionally very wide vehicles that come in various shapes and types; from bridge reclaimers to overarching portal reclaimers and the bucket-wheel reclaimers which superfluously resemble a bucket-wheel excavator in appearance. Reclaimers, as its name implies, 'reclaim' bulk material such as ores and cereals from a stockpile dumped by a stacker and are quite large, with bucket-wheel types usually having a boom length of 25 to 60 meters. As such, these two vehicles often work in conjunction with each other. Tunnel boring machines Large underground vehicles designed to drill and create subterranean subway transits, some of which weigh about 5,000 tons. NASA crawler-transporter An ultra-heavy transporter used to ferry spacecraft to the launching pad. At 2,000 tons each, they are the largest ground vehicle that still use an internal combustion engine as its source of propulsion rather than being reliant on an external power source. Gantry cranes and container cranes Mobile gantry cranes and container cranes are notable for their large, imposing size and dimensions with weights varying from 900 tons up to 2000 tons. These vehicles are either driven by wheels or rails and require a small crew for their size. The largest gantry cranes such as Samson and Goliath are known to be one of the largest movable land machines in the world, with the Honghai Crane being the largest and the most powerful of its kind at 150m tall, a span of 124m and the total weight of 14,800 tons, with the strength to lift up to 22,000 tons. Breitspurbahn A proposed civilian railway line envisioned by Adolf Hitler. These super enlarged transit lines would have accommodated ultra-wide trains that would be 500 meters (1,640 feet) long. Design concepts The Walking City – A form of drivable arcologies. Parades and events Barbados Landship