Over the roar of belching diesels and the hiss of cutting torches, a worker wearing the distinctive robin's egg blue hard hat of California builder Rudolph and Sletten taps on a Tablet PC to view a CAD drawing on a remote server.

Elsewhere on the sprawling construction site, a manager's Palm Treo delivers a schedule change for a meeting with a subcontractor, and a budget overseer from the contractor's regional office flips open his wireless laptop for a meeting in the job site's mobile-home-like quarters.

The Redwood City, Calif., company, one of the leading West Coast builders, specializes in high-tech buildings for high-tech clients, including bioscience companies, and for high-profile universities and hospitals. Past efforts included Microsoft's Bay Area campus, Sun's R&D campus and large projects for CalTech and Stanford.

Today, the general contractor routinely uses four types of wireless nets, all with a single purpose: to allow an increasingly mobile and computerized workforce to gain access to the company's critical applications. These include construction planning and management programs, calendars and e-mail.

The network strategy was forged by CIO Sam Lamonica, who joined the company two years ago. His goal was to exploit mobile technologies to put computer power into people's hands, so they could connect to central applications at any time and tie into the stream of e-mail and schedule changes that govern the daily and weekly rhythm of the company.

The first step was to make mobile e-mail and scheduling available via Treo and Research-in-Motion BlackBerry devices over cellular services from Sprint and Nextel. "We rolled these out, and they caught on rapidly," Lamonica says. "This has been a huge benefit for us."

The Treo, a combination cell phone/PDA, is "darn near a replacement for some laptops," he says. "They have wireless access to e-mail, contacts, calendars, voice and the Web. It opens any attachment, including PowerPoint and Excel. It provides someone like me pretty much all the functionality I need when I'm on the road."

The next step was creating connectivity for laptop users moving between Rudolph and Sletten's headquarters, three regional offices, and as many as 50 job sites. Lamonica chose Airespace (now part of Cisco), in part because of the depth of its wireless security features.

Airespace wireless LANs were rolled out first at the headquarters and regional sites, and then to a growing number of work sites. "The wireless LAN is now almost a standard deployment," he says. There are roughly 40 access points up and running, all centrally controlled. Laptop users simply open up their computers, authenticate and start computing.

The wireless LANs also simplify network functions at job sites where railers are set up near each other over time. "People can just start working right away, because the wireless LANs overlap," Lamonica says. Visiting architects or subcontractors can get guest access accounts, which lead only to the Internet, for example. These users then fire up VPN software to reach their corporate networks.

Wireless mixWas there a way to get WLANs to overlap an entire job site, to support the growing number of Tablet PC users and more dispersed office trailers? Lamonica's team evaluated outdoor WLAN mesh products from BelAir, Strix, and Tropos, and they chose BelAir.

In a wireless mesh, similar to the Internet's topology, access points can interact without wires to create an optimal path for data packets. Conventional wireless LANs require each access point to be wired to a LAN switch. A mesh can be simpler, faster and cheaper to deploy, and has a greater range compared to conventional WLANs.

The initial pilot test ran into a variety of problems, almost all of them related to the nodes' firmware, Lamonica recalls. Once those got resolved, the mesh "came right up," he says. "Performance has been good." Tablet PC users now have "total access to the business applications on our servers."

Satellite links, which are relatively slow and expensive, are reserved for special cases. "Sometimes we can get voice service but not broadband or T-1 data links," Lamonica says. "Just recently, we found one site that couldn't even get voice." The contractor sets up a dish and router to deliver the network connection. Lamonica is starting to look at VoIP services, including Vonage. One option is to use Vonage over the IP satellite link to support voice at an isolated job site.

Driving the wireless deployments are not hard savings or other quantifiable metrics, but rather the benefit of being connected anywhere, anytime. "We're seeing our dependence on wireless," Lamonica says. "When it's not working, the number of calls I get at the help desk jumps way up."

Two main mobility challenges have been the durability - or the lack of it - of mobile devices at construction sites and the generational differences in computer literacy among employees.

"We love the Treos, but they're not as rugged as we'd like," Lamonica says. But the alternative - handheld PCs designed for use at hard locations - is cost prohibitive, especially given the rate of change in handheld computers, he says.

Older employees have been slower to adopt the new technologies. Lamonica is addressing that partly through training for all employees and partly by relying on a kind of gentle peer pressure to motivate workers. "If you miss an e-mail from the boss, and the guy next to you gets it [through a mobile device], you notice that," he says.