Connecting the Dots: Using Global Positioning to Lay Out a Parking Lot

Executing a basic parking lot layout is old hat to many striping contractors, but that's only true when the layout and design are straightforward, the lot can be squared up, and there's enough time in the schedule to make sure it all gets done right.

But when those elements aren't in place, and the project goes from challenging to darn near impossible, how do you get it done? That's the question Vinny Toth, owner of V&V Line Striping, Boonton, NJ, asked himself last year after he was awarded the striping on a redesigned layout of a parking lot at Six Flags Great Adventure. The repair and sealcoating job, done by Advanced Pavement Technologies (and profiled in the March/April 2006 Pavement) was fraught with its own pitfalls, but the whole reason for the sealcoating job was to redesign the layout. The park's engineers needed to add an additional 1,000 parking spaces—despite having taken a bite out of the parking area with the footprint for a new roller coaster.

"When we bid it we planned on creating a nice square and laying out the parking within that square," Toth says. "We could have done that but we would have lost parking spaces and they couldn't afford to do that. So after I saw the layout they needed, I said to myself, ‘Now that I've got this, how are we going to do it? And how are we going to do it in such a tight time frame?'

"Most jobs are consistent with themselves," Toth says. "On this job nothing was consistent and nothing was square. Each part of the lot was different all the way across. Six Flags wanted one drive lane, with one-way traffic, but not even like a wishbone.

Some angles were 30 degrees, some were 45 and some were even 40 degrees. That's what made it so difficult. If you have it square and you have 45 degree angles throughout and it's consistent over 10 rows you can snap a line right across and it's pretty easy to lay out." Toth says. "But Six Flags couldn't afford to lose any spaces so we had to lay out each and every row differently."

How GPS helps stripers

So Toth turned to Fred Stewart, Stewart Surveying & Engineering LLC, Rockaway, NJ, which V&V has relied on in the past for unusually difficult layouts. Stewart, using a Leica Geosystems GX 1230 GG global positioning system (GPS), was able to ease the layout, increase the confidence level of V&V and its crews, enable the crews to work more quickly, and provide an opportunity for V&V to both finish the job on schedule and for profit.

Working as a subcontractor to V&V, Stewart essentially assumed the responsibility for the layout the park wanted.

"V&V wasn't responsible for the layout, I was," Stewart says. "So rather than Vinny having to worry about laying out a certain angle, we had it all figured out for him. All V&V had to do was go out there and snap their chalk lines off our marks, and start painting. They could basically do the striping off my points and check on themselves every few feet."

Stewart says most jobs require at least two visits to the site: the first visit to set up a control network of GPS points; the second to mark points for the stripers.

"We start with the engineering drawings so we know what the finished job is supposed to look like," Stewart says. "Then we coordinate that engineered layout with the GPS coordinates we're using in the field. Then, using the computer, the engineering drawing, and the GPS map we assign numbers to key points within the striping area."

Any GPS unit receives signals from a satellite. The GPS unit manipulates the signals into coordinates indicating a location on the Earth. The coordinates are related to a set of known coordinates, in this case GPS coordinates of a state GPS map.

At the Six Flags site Stewart set up a "base station" with one GPS unit at a known GPS coordinate (a surveying marker already placed in the ground). Once the base station is established, Stewart dons a "rover station," which includes a backpack unit with a pole-mounted antenna. As the rover walks across the site, the rover and base stations communicate with one another and with the satellite. Through triangulation (the satellite, the base, and the rover) Stewart can pinpoint a location on the Earth and assign that location coordinates.