Surveying AZ Trail in Pima County
Posted: Apr 15 2011 1:44 pm
HAZ ADMIN REQUESTED THIS BE MOVED TO MY triplogs. IT IS LISTED THERE AS AZ TRAIL SURVEY. COMMENTS HERE WILL LIKELY GO UNNOTICED BY ME. I APOLOGIZE IN ADVANCE FOR ANY INCONVENIENCE.
I thought this may of interest to some of the members/viewers but be warned, this will not likely be an exciting topic.
I volunteered with the AZ Trail Association in the early part of the year. I offered to survey a 30 mile segment between the Rincon and Santa Rita districts of the Coronado National Forest. The majority of the segment crosses State Trust Land and a survey is required, along with a legal description of the 15 foot trail easement. The AZ Trail Association was grateful for the offer as was Pima County Parks and Recreation.
This is an entirely volunteer effort with a 3 person team. As team leader, I'll be handling the actual field work and necessary research, as well as preparing the final survey drawings and legal descriptions. One of my good friends and long time surveying mentors has volunteered the use of his GPS equipment. Another Surveyor friend will be handling the post-processing of the GPS data.
We are utilizing a Trimble 4800 receiver. It is a survey grade L1/L2 receiver. It is a little on the large size by today's standards, but lightweight enough to carry comfortably in a Kelty frame pack. The goal is to locate the entire trail segment (obviously) as well as locate adequate Public Land Survey System (PLSS) cadastral monuments. The monuments were originally set in this area between 1875 and 1934. The monument types range from chiseled stones to iron pipes affixed with brass caps. From the viewpoint of a Land Surveyor, this project will be a lot of fun. Mixing hiking with searching for and collecting physical evidence is why many Surveyors have found a home in the profession.
The methodology will be a straight forward kinematic style survey. I occupy the PLSS corners with survey grade precision. This is a 'static' observation which entails mounting the receiver on a survey rod affixed with a tripod. The occupation times will be 10 minutes, recording data at a 5 second interval. The trail will be hiked using a 'roving' kinematic style. The receiver will be securely mounted in the backpack with the upper flap of the pack open. The recording interval will also be 5 seconds. The receiver will be recording data about every 20 feet at a hiking speed of 3 mph. I will also be able to collect additional data points as needed, utilizing a hand held computer interface (AKA; data collector).
I'll download the data daily and email it to the post processing team member. He will be utilizing Continuously Operating Reference Station (CORS) data from the National Geodetic Survey (NGS) to fix our data to the 1983 North American Datum (NAD 83). This is a horizontal datum that is pretty much the accepted survey datum used by Land Surveyors in the US. It is based on the WGS 80 ellipsoid model whereas GPS utilizes the WGS 84 ellipsoid. The two projections are very close which makes GPS easy to use when referencing NAD 83 datum. This is about the technical limits of this discussion. Those interested in learning more about the technical stuff can visit the NGS website.
The first day of the survey was last Sunday (4/10) and I focused on locating some of the easier to access PLSS corners and familiarizing myself with project access points. This weekend, I will continue locating PLSS corners and will hike a segment of the trail to see how the data set will process. I have broken the project into two portions; north and south with I-10 being the dividing line. I anticipate locating the majority of the PLSS corners in the southern portion first. Next I will hike the southern potion of the trail and will likely complete it on two separate days. After we are satisfied with our results, I'll move to the northern portion using the same procedure.
There will be adequate redundancy in the location of the PLSS corners by multiple occupations on different days, and/or comparing our corner locations with modern resurvey information found in the public records. I hope to acquire some recent aerial or satellite imagery to verify the actual trail alignment. If not, then the trail will be hiked twice on separate days for redundancy. To the laymen this may seem like overkill; for the Professional Surveyor, redundancy is a necessary part of any survey endeavor.
I'll post here from time to time and would like to include photos for those of you that are interested. (I'D APPRECIATE INPUT ON POSTING PICS THAT WILL LINK TO THIS FORUM TOPIC. THANKS) I welcome comments and will do my best to answer all inquires. I don't anticipate needing any additional team members at this time. A big part of my motivation is doing the project with a minimal size team. In the world of land surveying, this would be considered a medium sized project.
Respectfully
Walkalot
HAZ ADMIN REQUESTED THIS BE MOVED TO MY triplogs. IT IS LISTED THERE AS AZ TRAIL SURVEY. COMMENTS HERE WILL LIKELY GO UNNOTICED BY ME. I APOLOGIZE IN ADVANCE FOR ANY INCONVENIENCE.
I thought this may of interest to some of the members/viewers but be warned, this will not likely be an exciting topic.
I volunteered with the AZ Trail Association in the early part of the year. I offered to survey a 30 mile segment between the Rincon and Santa Rita districts of the Coronado National Forest. The majority of the segment crosses State Trust Land and a survey is required, along with a legal description of the 15 foot trail easement. The AZ Trail Association was grateful for the offer as was Pima County Parks and Recreation.
This is an entirely volunteer effort with a 3 person team. As team leader, I'll be handling the actual field work and necessary research, as well as preparing the final survey drawings and legal descriptions. One of my good friends and long time surveying mentors has volunteered the use of his GPS equipment. Another Surveyor friend will be handling the post-processing of the GPS data.
We are utilizing a Trimble 4800 receiver. It is a survey grade L1/L2 receiver. It is a little on the large size by today's standards, but lightweight enough to carry comfortably in a Kelty frame pack. The goal is to locate the entire trail segment (obviously) as well as locate adequate Public Land Survey System (PLSS) cadastral monuments. The monuments were originally set in this area between 1875 and 1934. The monument types range from chiseled stones to iron pipes affixed with brass caps. From the viewpoint of a Land Surveyor, this project will be a lot of fun. Mixing hiking with searching for and collecting physical evidence is why many Surveyors have found a home in the profession.
The methodology will be a straight forward kinematic style survey. I occupy the PLSS corners with survey grade precision. This is a 'static' observation which entails mounting the receiver on a survey rod affixed with a tripod. The occupation times will be 10 minutes, recording data at a 5 second interval. The trail will be hiked using a 'roving' kinematic style. The receiver will be securely mounted in the backpack with the upper flap of the pack open. The recording interval will also be 5 seconds. The receiver will be recording data about every 20 feet at a hiking speed of 3 mph. I will also be able to collect additional data points as needed, utilizing a hand held computer interface (AKA; data collector).
I'll download the data daily and email it to the post processing team member. He will be utilizing Continuously Operating Reference Station (CORS) data from the National Geodetic Survey (NGS) to fix our data to the 1983 North American Datum (NAD 83). This is a horizontal datum that is pretty much the accepted survey datum used by Land Surveyors in the US. It is based on the WGS 80 ellipsoid model whereas GPS utilizes the WGS 84 ellipsoid. The two projections are very close which makes GPS easy to use when referencing NAD 83 datum. This is about the technical limits of this discussion. Those interested in learning more about the technical stuff can visit the NGS website.
The first day of the survey was last Sunday (4/10) and I focused on locating some of the easier to access PLSS corners and familiarizing myself with project access points. This weekend, I will continue locating PLSS corners and will hike a segment of the trail to see how the data set will process. I have broken the project into two portions; north and south with I-10 being the dividing line. I anticipate locating the majority of the PLSS corners in the southern portion first. Next I will hike the southern potion of the trail and will likely complete it on two separate days. After we are satisfied with our results, I'll move to the northern portion using the same procedure.
There will be adequate redundancy in the location of the PLSS corners by multiple occupations on different days, and/or comparing our corner locations with modern resurvey information found in the public records. I hope to acquire some recent aerial or satellite imagery to verify the actual trail alignment. If not, then the trail will be hiked twice on separate days for redundancy. To the laymen this may seem like overkill; for the Professional Surveyor, redundancy is a necessary part of any survey endeavor.
I'll post here from time to time and would like to include photos for those of you that are interested. (I'D APPRECIATE INPUT ON POSTING PICS THAT WILL LINK TO THIS FORUM TOPIC. THANKS) I welcome comments and will do my best to answer all inquires. I don't anticipate needing any additional team members at this time. A big part of my motivation is doing the project with a minimal size team. In the world of land surveying, this would be considered a medium sized project.
Respectfully
Walkalot
HAZ ADMIN REQUESTED THIS BE MOVED TO MY triplogs. IT IS LISTED THERE AS AZ TRAIL SURVEY. COMMENTS HERE WILL LIKELY GO UNNOTICED BY ME. I APOLOGIZE IN ADVANCE FOR ANY INCONVENIENCE.