Perched high above the city skyline operating aircraft-style joysticks, tower crane operators must sometimes feel as if they are flying. That feeling could be heightened if a new development in head up displays (HUDs) takes off.

HUDs, which overlay digital images on windows, could mean that crane cabs – mobile and crawler as well as tower – gain more than a passing resemblance to combat jet cockpits.

HUDs enable today’s fighter pilots to see speed, height, and attack details without looking away from the direction of travel. In the same way, HUDs could allow crane operators to view important information such as wind speed, load information, and jib angles without taking their eyes off the load or landing point.

PAT, the electronic control systems company within Hirschmann, made public its commitment to HUDs at Cranes Today’s Crane Safety & Management conference in Amsterdam in June, when director of research and development, Ulrich Molter, staged a presentation on the technology.

Molter believes that current information devices in cabs are not always convenient. For example, he observes that the positions of displays are sometimes less than ideal, and readability can be impaired by reflection or solar glare. Also, he says, too much information can be a hindrance when more relevant and precise data could be related to the operator.

It is early days, but Molter believes HUDs have a promising future in cranes provided operators are made aware of their advantages. “We want to make the idea of HUDs known to people, and then it will be a case of waiting for the customers to respond,” he says. “I think the technology will be introduced eventually, but it is just a case of the time in which that will happen.”

Molter admits that he wonders whether the industry is ready to adopt such advanced technology at present. But he is confident that HUDs provide great advantages to operators, and believes that their appeal will eventually become irresistible.

“By the end of the year we will have a good idea of where we stand,” he predicts.

HUDs have already proved themselves in cars, although their use is so far restricted to luxury vehicles. For example, BMW provides a system where drivers can view a wide range of information –speed of travel, remaining fuel, and so on – on their windscreen, without having to look at the dashboard..

In cranes, operators may need to know the distance of the load from the ground, or the weight of the load they are lifting. On complex jobs, the distance between two cranes and the wind speed would also be crucial information. HUDs would enable operators to absorb this information without taking their eyes off proceedings, says Molter.

He emphasises the logic behind placing information on the windshield, claiming that information is recognised in half the time it takes to assimilate information from conventional instruments. But the benefits don’t stop there. The use of real graphics is possible as opposed to old-fashioned dials and gauges. This can allow information to be presented in a more easily digestible form.

Potential drawbacks could include problems with seeing the displays, say, because of bright sunlight. However, PAT argues that the brightness of displays could be controlled automatically to allow for weather and condition changes. For example, explains Molter, in bright sunlight the display would be tinted so the visual image remained clear. Operating cabs would need to be redesigned to accommodate such a facility, but PAT insists that this would be less disruptive than it may at first appear.

Gregor Leuschen, PAT’s international product manager, was interested to observe the reaction to Molter’s presentation at Crane Safety 2005. “Some big OEMs seemed to warm to the idea, and I am hopeful that it will catch on,” he said. “But it is too early to make predictions because the idea is still in its infancy.”

PAT has trialled its HUDs on a telescopic crane, but Leuschen reckons the technology will also be useful on lattice boom crawlers and tower cranes.

Peter Olinger of German-based tower crane company Terex Peiner respects the idea, but believes it has a long way to go before it becomes a practical option on cranes.

There are several things that concern him. He says that PAT will need to prove to the market that the system is dependable, works well outdoors, and is affordable. However, he adds: “Although there are a lot of technical questions to clarify, it does have a good chance for the future.”

Olinger concludes that Terex Peiner could only make an accurate assessment of the technology once it had been tested in real conditions over a long period.

Mark Sovocool, director of engineering and fabrication at Las Vegas-based crane rental company Jake’s Crane & Rigging, reckons it makes perfect sense to introduce HUDs to the industry. Jake’s already employs a system where operators can view crucial information and diagrams of the crane on a laptop in the cab. Sovocool believes it would be natural progression to overlay this sort of data on the windscreen.

He offers the example of an operator looking at the laptop to view the boom angle radius, engine performance, or temperature. “It certainly makes sense to put this information where the operator could see it most clearly,” Sovocool concludes.

However, it is doubtful that HUDs would be able to show all the information that a crane operator needs. For example, Alain Voyatzis of tower crane anti-collision specialist SMIE, does not believe that HUDs could be employed for safety critical applications such as displaying the distance between two cranes. He says: “We work with the specifics of spacial control, and a technology like this doesn’t effect us.”

Wylie Systems’ technical director Frank Beardsley now deals with crane safety instrumentation, but he was a fighter pilot during the Vietnam War. He is complimentary about PAT’s initiative, but is also skeptical about the use of HUDs in cranes. He says that they could distract operators, particularly if irrelevant information was presented. “The technology is used in the automobile industry, and it’s a clever thing, but if I was driving a car I’m not sure I’d want the speed I was travelling constantly on the windscreen in front of me,” he says.

Besides, he adds, cockpit windscreens and crane windows are completely different. Notwithstanding PAT’s reassuring on this score, he believes that sunlight could interfere with images and their interpretation. “We’re not looking into this technology at this stage, and I doubt it will catch on,” he says.

Lewis Ng, group marketing manager of Singapore-based crane supplier Tat Hong Holdings Ltd agrees. “While lifting a load, the operator’s eyes are constantly on the load,” he points out. “If they need to check the computer, they should stop moving the load, and look before proceeding.”

Ng continues: “[The HUD] might cause the operator to be complacent, and not stop moving the load while focusing his or her eyes on the displayed information since it is in their line of sight.”

Moreover, Ng says, the quality of the display might be compromised if the cabin is dusty, especially if this dust covers the projection or reflective lens.

Netherlands-based Orlaco supplies crane cameras to solve viewing problems.

Director Henrie van Beusekom admits that his company has experimented with HUD technology, but he doubts its viability in crane applications. Of course, as a camera company, Orlaco would be concerned only with HUDs showing high-resolution video images. The HUDs that PAT is investigating are far simpler – it is experimenting with data such as symbols and measurements.

Nonetheless, van Beusekom sees potential obstacles to their use. First, he says, crane cabs would need to be completely redesigned to be compatible with high resolution HUDs. He believes that they would allow too much sunlight into the cab, and the clarity of video images would not be good.

Secondly, he says the use of flat monitors in cabs is sufficient for operators: “Nobody is breaking my door down to say they need HUDs because they have no room in the cab or they are craving better vision.”

Flat monitors did not take up much room anyway, and one of the main selling points of HUDs is that they save room in the cab, he adds.

Finally, he believes the technology would have to overcome the crane industry’s innate conservatism, which makes it reluctant to embrace new ideas.

The next 12 months will decide whether HUDs are to become ubiquitous operator assistance devices, or just another fashion destined to become a fashion victim.