Walt Disney World has issued written orders and made software changes designed to ensure that navigational computers on the resort’s buses can’t be used while the vehicles are moving. The changes followed criticism from some of Disney’s roughly 1,200 bus drivers who complained that the computers were a distraction and a safety hazard. “We’re a listening company and constantly ask for cast-member feedback. In this case, we heard from bus drivers that there was a need to clarify operating guidelines, and we have developed a written communication to address that,” Disney World spokeswoman Andrea Finger said this week. Disney installed the onboard, GPS-equipped computers several years ago as part of a project the company dubbed “Magic in Motion.” Under MiMs, as the project is referred to internally, Disney is able to track in real time the locations of all of its buses and the crowd levels at the bus stops outside its theme parks, hotels and other venues. Rather than following pre-determined routes, the buses are continually redirected during the day depending on where passengers are waiting. Disney initially designed the system to be automated but has so far been unable to make it so. As a result, drivers who are completing a circuit must radio to dispatchers for their next assignment and then enter a five-digit code into an onboard computer, which then updates everything from the marquee on the front of the bus to the informational announcements and themed music playing for passengers. Some drivers say using the computers can be distracting as they drive. The criticism grew louder this spring following a series of Disney bus accidents, including one inside the Fort Wilderness campground in which a 9-year-old boy was killed, and another near Epcot in which a driver and a child were seriously injured. Authorities have said they do not think driver distraction was a factor in either of those crashes. Disney officials say they think MiMs has improved safety for drivers by relieving them of some responsibilities, such as making passenger announcements. And the resort says it has long trained drivers to enter route codes only when their vehicles are stopped. Still, the resort has made changes in recent weeks. Among them: Software updates installed this spring that ensure the computers can be used only while the buses are at a standstill. Previously, the computers could still be used while the vehicles were traveling at very low speeds. And late last week, Disney issued written guidelines to its drivers outlining specific points at which they should radio dispatchers and enter route codes. Drivers returning to the Magic Kingdom, for instance, are instructed to enter their codes only while stopped at the parking-lot toll plaza, at one of two traffic signals, or at their assigned load zone.