• Dale Hill

April 2021 'Drive-By' Survey Marks

Updated: May 4


While most of my recoveries are on hikes or specific outings where I'm looking for one or more specific markers, there are the ones that are just 'along the road'. I call these 'Drive-By' recoveries because I'm driving with my GAIA GPS USGS Topo map in 'follow' mode and I can see the benchmark notations along my route. It's mostly about keeping your eyes open and paying attention.


Many markers are located along active roadways, use common sense, take appropriate safety precautions, and exercise due care to avoid potential injury. If you choose to search for survey marks it is at your own risk. Please do not disturb or remove Survey Markers!


April 2, 2021 - SR 78, Ramona, CA


San Diego County Surveyor Monument RA 157


This County Surveyor Monument is located about a hundred feet north of the intersection of SR 78 and 2nd Street. If the witness stake hadn't been there, it would have been challenging to locate as it was buried in the dirt and debris. Once I uncovered it, I brushed it off and applied liquid chalk to call out the stamped marks. Even though there are a lot of these on the map, that doesn't mean they're easy to find or still there, but I expect to recover a few of these every month 😊

April 8, 2021 - SR 78, Ramona, CA


DX0256: X 521 1956 - Elevation 2,569 Feet


This is one of those Bench Marks that I drive by often when I'm headed to anywhere north of Ramona on SR 78, it's located not too far past the point where Old Julian Highway connects to the 78. Unfortunately, it's on a stretch of road with a minimal shoulder and the traffic is usually pretty busy when I'm passing through so I mentally tag it for another day. This morning I was out early specifically looking for survey marks on the GPS on Bench Marks program, traffic was light so I pulled off further the road where the shoulder widened and hiked back to the general location indicated on my map. As is often the case, it wasn't located exactly where the map legend had it, and it took some wandering around on the embankment to find it, but I did and it was in good shape.


April 8, 2021 - SR 78, Santa Ysabel, CA


DX0245: T 521 1956 - Elevation 2,920 Feet


When you know where to look, survey marks can be remarkably easy to spot. I had just recovered a GPS on Bench Marks disc and was headed back down the 78, my Topo map indicated a BenchMark ahead and as I approached the little bridge/culvert I could see the mark mounted right on top! Easy-Peasy.

April 11, 2021 - SR 78, Santa Ysabel, CA


DX0247: U 521 1956 - Elevation 3,014 Feet


Today was another successful day of recovering survey marks for the GPS on Bench Marks program and as I was heading back home I thought I'd stop and look for this Bench Mark that shows up on the Topo Map very close to the entrance to the Santa Ysabel Open Space Preserve West Staging Area.


There was plenty of parking and there appeared to be some rock outcroppings under the trees that would be ideal locations for the mark. The grass along the shoulder was deceptively high, as I worked over to the first rock outcrop the grasses were up over knees and disguised the soft and uneven ground. I was in sneakers and not wearing my usual gaiters, so I was mindful of the potential for ticks and snakes as well as twisting an ankle.


I was surprised NOT to find the mark on the rocks where I had anticipated it, so I walked along the berm kicking around in the grass looking for a concrete monument that was hidden in the tall grass...still nothing. I'd already had a good day and I wasn't super invested in finding this one so I decided to head back to the truck when I glanced at a large flat rock on the opposite side of the road. Sure enough, the mark was mounted in the top of the outcrop just on the other side of the barbed wire fence. Carefully reaching through the fence, I was able to get a good picture of the mark.


It's interesting to note the numbering of these Bench Marks, a couple of days ago I recovered T 521 and X 521 (see above), this is apparently another mark that was part of that surveying project, likely a road survey for SR 78.

April 18, 2021 - SR 67, Lakeside, CA


California Dept. of Transportation Mile-Marker


This was kind of a cool and unexpected find. Coming back from La Mesa, I was going through Lakeside on northbound SR 67 when I noticed a Benchmark notation on my topo map just ahead. There was plenty of room to pull off the road so I parked, hopped out, and started looking. I saw a T-bar fence post and an old lathe stake sticking out of a 3-inch PVC pipe that was about 18-inches high. Since this was sitting on a berm between the road and a private drive, and there were no other fence posts, it was very likely a witness post for the benchmark. However, there was no mark. If it had been there it was likely the victim of erosion or the grading of the embankment.


Instinctively, I scanned the nearby area for other indications of the mark: mostly other witness posts, concrete monuments, flat bedrock, or boulders that could have been used as mounting locations. There were some boulders a couple of hundred yards up the road, but they were too far from the mark to be viable candidates. I headed back to the truck and slowly moved along the shoulder waiting for a break in traffic when I came alongside a witness paddle marking an aerial target on the ground.


Aerial targets are used as control points in aerial mapping surveys and look like a big plus-sign or an "X". They are usually painted on the pavement with white paint so they can easily be seen from an airplane, if the control point is not on the pavement, strips of white plastic material are temporarily affixed to the ground to mark the spot. I thought it was odd to have a witness paddle nearby since the X was already visible from the air, so I stopped and checked it out.

To my surprise, under the center of the plastic strips that made up the X was a California Department of Transportation disc! It was stamped "67-9.35 1984". When I got home, I did a quick map check and confirmed that this was a mile-marker noting mile 9.35 on NB SR 67 (SR 67 officially begins in El Cajon at mile 0.) This was NOT the benchmark noted on the topo map, that one was a traditional benchmark T 281 set in 1955 (PID: DC0655), based on the description of its location, it may be lost or destroyed during road resurfacing.


April 24, 2021 - SR 371, Riverside County, CA


DX0577: B 586 1939 - Elevation 3,166 Feet


Today I hiked Mount San Jacinto with my friend Alberto, we carpooled in my truck from Ramona to Idyllwild. Of course, I had had my GAIA up and running in follow mode with my USGS Topo Map active. I was pointing out marks on the map left and right to Alberto explaining the process of how I locate my "Drive-By" recoveries. Since we had a full day of hiking ahead of us and it's better to start earlier rather than later, I passed on stopping to recover any marks along the way...LOL, it was killing me! If I'd been by myself, I would've easily recovered half a dozen or more before deciding I needed to get my butt to the trailhead! 🤣 I told Alberto that I'd plan to stop along the drive home and pick off one or two of the easier marks. This was a super obvious recovery and is a good example of how easy these can be to locate when you know what to look for. I saw the legend pop into view on my GAIA as I was going down the 371, based on the map symbol, it was on my side of the road just ahead. It turned out to be at the end of a dirt parking pull-off/parking area for a roadside business, as I pulled off the road I could see the rock outcrop at the end of the parking area. When I pulled up to the rock, I could clearly see the mark from the truck! A little chalk to pull out the details and done!


California Dept. of Transportation Mile-Marker


With two red and white CalTrans Witness Posts marking the spot, this one was a no-brainer. It's funny, on our drive out in the morning we based a sign for "Farmy Farms" that gave us a chuckle, it turns out that it's an Organic Farm/Farm Stand located along the 371 in Aguanga (I love the name!) right after we passed it I saw these two witness posts, spaced a few feet apart on the side of the road. I told Alberto we were definitely going to stop to recover this one on the way back as it's just TOO easy. Sure enough, on the drive back I easily located the marks and pulled off on a nearby dirt road to go investigate. These markers don't show up on the Topo Map and are rarely listed in the NGS database. Placed by various transportation entities that ultimately became rolled up in what is currently CalTrans. They are clearly tied to road surveys and usually show the post-mile for the route, this particular one is at post-mile 60.23. SR 371 is the main highway serving the communities of Anza and Aguanga and connects both towns. SR 371 crosses through the private community of Lake Riverside, as well as Cahuilla and the Cahuilla Indian Reservation. It is the primary road running through the town of Anza but mostly serves rural areas. You can see more history of various California State Routes at the California Roads Portal on Wikipedia



Initially, I had included the recoveries I made for the GPS on Bench Marks program in with my "Drive-By" Recoveries, but I opted to separate them into different posts. The GPSonBM recoveries are planned recoveries, while they can be considered Drive-Bys, I do research them fully before heading out specifically to find them.

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