- SPECIAL REPORTS
- THE MAGAZINE
The next day, my supervisor, Eric Cenovich, RLS, president of Western Air Maps Inc. (WAM) of Overland Park, Kan., called to tell me that we won a project mapping the Grand Forks Air Force Base (AFB) in Grand Forks, N.D. It sounded like a good job—aerial photography and mapping with the requisite ground control and support. But I could not imagine that security officers at an Air Force Base would allow me access to the base any time in the six months following the attack, let alone in the two upcoming weeks. Sure enough, it was seven days from that first call and 30 days after September 11th that I was on my way from Kansas to North Dakota to find out.
Project Elements In LineScott Bassingthwaite, GIS manager of Grand Forks AFB was clear in the objective of the project: “Acquire aerial photography for the development of a Geospatial Information System database consisting of topographic and planimetric feature data development for the Grand Forks AFB.” He had the funding approved for the project and felt very strongly that the project should proceed even after the horrendous occurrence of September 11th. It was at that time that President Bush called for Americans to go about their business, and this certainly came under that request. The ground control portion of this project required that, according to the contract, “new first-order monuments should be established ... and the new control network should support personnel using conventional line-of-sight electronic distance measuring equipment, as well as data collection systems that reference satellites to determine accurate positions (GPS). All ground control surveys will meet at least first-order accuracy.” Survey crews were to place fabric control points throughout the installation. The “fabric control points” meant targeting the points that would become permanent monuments. WAM was also needed for airborne GPS (ABGPS) where I was required to be onsite while the photography was taken. The last need was for establishing photographically identifiable points that could be used with the targets to sufficiently control the subsequent mapping.
Grand Forks AFB is home of the 319th Air Refueling Wing, an integral part of all major military actions since its formation in 1950. The 319th Civil Engineering Squadron’s mission includes the need to “...sustain installations for the projection of aerospace power in peace and war. Construct, operate, maintain and repair all real property on Grand Forks AFB.” Getting an updated photographic base that would become the basis for the basewide GIS would prove very valuable.
Check, Check…We at WAM had a well-thought out plan to complete the Grand Forks project. I was to drive nine hours, build monuments, target the monuments, take GPS photo points, conduct ABGPS and then tie the GPS-located monuments to first-order accuracy. I heard about the job on a Thursday, read the specifications the Saturday after, and was given the go ahead to work the Monday after that. The autumn flying season can be short so off I went with the nagging thought that I was going to an Air Force Base during a national emergency to lay out giant targets throughout the base.
I was skeptical about being allowed access to the base until I got to Grand Forks and met with Bassingthwaite. He walked me through the process of getting a 30-day contractor’s pass. The only restrictions I would encounter while working on the base, I was told, were regular vehicle checks before entering the base and the requirement to show my pass to enter any and all buildings on the base. The vehicle checks proved to be a minor delay in the workday, but it can be very intimidating having armed guards and the occasional bomb-sniffing dog scour through your truck several times a day! You don’t normally think of people going through your truck on a standard survey project. Of course, there wasn’t much of interest to the guards (or the dogs).
I did, however, have some tense times like on the very first day when I realized I hadn’t taken my shotgun out of the truck. It was near bird season and I had put the gun in the truck several weeks earlier. Fortunately, I remembered the gun was in there before I went through the first check, so I didn’t have to explain that one! Another restriction required showing my pass just to go to the restroom!
After the targets were laid and the day was ending, we checked to see if the forecast would hold for the next day. It was to be a beautiful day so I scheduled a time to meet up with the aerial crew at the local airport. At that time the Airborne GPS was dependent on using one of my Trimble 4000 SSE receivers (Trimble, Sunnyvale, Calif.) attached to the camera to record the GPS location of each photograph. While they flew I had the two receivers collecting data on the ground. After about an hour of flying we had all that was needed. The next week I spent post-processing the ABGPS data. This allowed the photogrammetry work to begin and kept several people busy mapping the base—an important part of my job.
After a week at home in Shawnee, Kan., I went back to Grand Forks to conclude the field portion of the survey project. That week’s work didn’t have the added pressure of coordinating time with the flight crew nor was I worried about having good flying weather. The first thing I did was target the photographically identifiable points with GPS. With the new aerial photography in hand the office staff picked about 20 points that could be used to supplement the targeting for control of the mapping. There was plenty of control on the base so all of these points were located in the surrounding countryside. Photo identified points are features that are visible in the photography that are appear accessible to the field surveyor. These include concrete pad corners, sidewalks, power poles, and often spots in the road. With new photography it is usually easy to locate points, and except for the occasional locked gate on the base, I was able to drive right to the points. The GPS constellation was very good in the morning so I was able to finish the GPS work and still have plenty of daylight to place the monuments for the permanent points required. Normally I would set the monuments and then target them but flying constraints had reversed that process. There were only seven monuments required, and except for some very hard ground I was able to dig and mark the monuments with brass caps in concrete in one long day.
One Last ObstacleThe next morning I woke to a blizzard that had been forecast as snow flurries. Before the day was through, Mother Nature would set an all-time record for that date and the month of October in Grand Forks of 10.8 inches of snow! I spent most of that day in my motel room except for an ill-advised morning venture out into the storm. I was, however, treated to the locals’ attitude toward such storms. When I stopped for gas, the owner of the small station had only one thing to say: “Snowing, eh.” The storm closed the base to most activities the next day, but that gave me free run of it and I was able to get some work done in spite of the conditions.
Once the monuments were dug out from under the snow, the GPS survey work began. This was fairly straightforward work, and with some excellent B order monuments courtesy of the North Dakota Department of Transportation, some very good quality surveying was done. The fieldwork is now done and the survey report is written. And although our country is still rebuilding what was destroyed, I got a view of the Armed Forces at a time of crisis. It was a very good view. The men and women that I interacted with were very professional and courteous at all times. At the end of the day’s work I stood with hat in hand and felt very fortunate for all I have and the job I do.
We at POB offer our condolences to the families, friends and associates of the seven astronauts lost aboard the Columbia Space Shuttle in February. This article reminds us of the bravery and selflessness demonstrated by our country’s many outstanding service personnel.