The back of the nondescript Malibu feels pretty much like any other, except for the beeping of the little Trimble GPS box sitting next to me.I've given up on conversation with the two fellows up front; they're too busy noting building addresses, turn restrictions, neighborhood restaurants and even gas stations.

Life with a NavTech data collection team is not very exciting, but their effort does add up: 130 people in 47 field offices across the United States who are devoted full-time to updating street information.That works out to 200,000 man-hours a year driving 1 million miles of U.S.roads.The result of that effort is a database that is in use by every in-car navigation system in the country and one that arguably is the most accurate digital US street network in existence.

The database is the core product of Navigation Technologies (NavTech), a nearly 1,000 person worldwide company headquartered in Rosemont, Illinois.NavTech produces digital street databases for the United States and Europe, with Far East coverage in the works, beginning with Japan.

At present, NavTech's US database covers several hundred city markets, encompassing over 50% of the U.S.population.

How it Works

NavTech coverage begins in 35 digitizer stations located in three U.S.production facilities.A variety of source materials, including U.S.G.S.quad maps, digital and paper maps from local municipalities, and aerial photographs are digitized in those stations to create the initial base map (The digitizing is done under the control of a customized version of ESRI's Arc/INFO software, controlled by RS6000 servers).

These base maps are then handed over to the staffers who will build and then maintain the street database on an in-house developed proprietary GIS system called Geographical Workstation System (GWS).Interestingly, operators of the GWS are the same people who man the in-field collection vehicles such as the one visited by Directions.NavTech's 47 field offices organize their workload so that individuals are responsible for specific geographic areas.

At some point early on in the process, the GWS operator begins in-car coverage of an area.As the car proceeds down a target street, a customized, differentially corrected, Trimble GPS collection system automatically takes readings 20 or 30 times a minute.In the meantime, the two-person team is noting addresses at the beginning and end of each block, the speed limit on the block, any turn restrictions at each intersection, and other attributes that will be noted in the database.

The database is designed to accommodate as many as 150 attributes for each individual street segment.If the street is one-way during Sunday church services, that fact is accommodated in the database.

At the GWS input screen, operators view the "track" left behind by the GPS collection as well as the digital representation of the street network.Street segments are then snapped to their actual location, as determined by the GPS data.

TIGER files are used as well, but principally for initial entry of address ranges.

What's amazing is that the manpower thrown at this problem is such that, for most areas of NavTech coverage, NavTech personnel have driven every single street!

The field office visited by this Directions reporter is located in Rosemont, Illinois along with the corporate headquarters.This office recently completed coverage of the Milwaukee, Wisconsin metropolitan area.Over the course of six months, NavTech data collection vehicles drove every street in the Milwaukee area.

NavTech targets customers from among auto manufacturers, system vendors, and the managers of major truck fleets.The popular MapQuest web site utilizes the NavTech database.Although not yet customers of NavTech, United Parcel Service and Federal Express are important targets.

Alas, these accurate street files are presently unavailable to users of desktop mapping software.But this may be changing; NavTech has agreed to supply its database as a part of future versions of Microsoft MapPoint 2000.Perhaps users of other mapping software packages will not have too long to wait.