text: Today, elevators are built under strict supervision of the Building Codes. Model Codes which are the standard in most US jurisdictions require compliance with the American Society of Mechanical Engineers' (ASME) standards for the installation, maintenance, and inspection of elevators. In Canada, the governing authority is the CSA (Canadian Standards Association). In addition other related standards are likely required to be complied with as specified by Local Authorities Having Jurisdiction.\n\nElevators are generally sold in prepackaged components which are inherently non-proprietary. All of the four major manufacturers sell proprietary microprocessor controls. Each manufacturer provides similar product designs, and the overriding issue for purchase is usually price and availability. In the case of renovations, the use of non-proprietary controls has become a large part of that business because it allows the owner to offer the maintenance contract to multiple bidders rather than accept a single manufacturer for the life of the elevator which can be more than 30 years. In some large campus type properties, the use of non-proprietary equipment in new construction has replaced the standard prepackaged product. Non-proprietary systems generally have a higher up front cost, but may be offset by allowing the owner to control the long term costs over the life of the elevator.\n\nIn some locations, the shaft and parts of the cab are made of transparent material for specialized "Scenic elevators." This allows riders to see outside the cab as they travel on the elevator. Some locations take advantage of this transparent material by placing the elevators along the walls of their building. This allows riders to see the outdoor environment as the cab runs along the side of the buildings. An example of this is the CN Tower in Toronto, Canada.\n\nToday, all new elevators are computer-controlled and microprocessor based. This allows the elevator system to place cabs where they are most needed in the interest of smooth running, with behavior based on analysis of building use called "Traffic Studies." Traffic Studies are done by professional elevator consultants who use specialized tools to determine the optimum size, speed and number of elevators for a building based on its peak use periods. Computer control also permits greater control of access to various floors of a building after hours and on weekends. Methods of access control include card readers, keys, and access codes entered into the control panel of the elevator.\n\nElevators are usually installed in a building during construction. Renovations may consist of replacements for hoistway (floor landing) doors, car doors, interior cab finishes, controls, hoist machines, hydraulic pistons and hall fixtures. At times renovations may also include replacement of the entire cab itself. In many instances the upgrading of components may require additional code compliance, these issues should be reviewed with an elevator consultant prior to the purchasing of new materials.