Frank, I've been doing them for decades when photographs are involved. Generally, I prefer to have a Land Surveyor provide photo control to me; but sometimes, clients prefer me to personally do the photo control too. However, I do NOT attempt to infer engineering conclusions from the data. I just present the measurments and leave the interpretation to an engineer or physicist that has been admitted to the Court as an Expert.
Note that when a Land Surveyor works on a project with me, I insist that an EDM calibration report (performed at an NGS Calibration Baseline) be submitted to the Attorney of Record as part of the deliverables.
When I get deposed, I want my photogrammetric measurements to have a valid provenance back to NIST and/or NGS. Attorneys rarely ask such of me, but if they do, I'm ready with an answer.
Have it locked and cocked, even if you don't have to pull the trigger.
I'd be careful there, as officers use a lot of sensitive equipment that requires calibration not the least of which are radar guns, and know the importance of correct documentation. The accident scene investigation report filed on my pickup included ppm, temp and pressure settings as part of the printout.
This thread is funny.
Do you guys see plumbers getting upset when you pick up a wrench?
Carpenters when you pick up a hammer?
They are using the same tools we use, but they're not getting the same information, nor are they using it in the same way.
Someone up above said it best....if you think this is work you wish to perform, or a service your firm wishes to offer, then get involved in learning and marketing forensic surveying.
Do you guys see plumbers getting upset when you pick up a wrench?
Carpenters when you pick up a hammer?
Well they sure did back in the union days. We were always fighting with the carpenters and the millwrights.
> ....Can a person not licensed as a professional land surveyor legally do detailed topographic survey work of an accident scene ...?
Oregon law contains an exception that allows law enforcement to do accident scene investigations. ORS 672.060(18).
If I was an attorney you can bet I would be seriously challenging the maker of such a map to prove his qualifications,to show his procedure for trapping errors in data, and for ensuring that his equipment was in proper working order. Anybody ever meet a cop at a calibration baseline?
> Do you guys see plumbers getting upset when you pick up a wrench?
> Carpenters when you pick up a hammer?
>
There is a boatload of money and frequently someones freedom and future at stake over these investigations. It is very important that they get done right. This isn't akin to hammering in a nail.
"...Anybody ever meet a cop at a calibration baseline?..."
Moderator's note: Personal insult removed.
Mark Please tell us what difference one foot makes in the difference for a speed/stopping calculation.
I can imagine the cross examination now.
Your honor this so-called expert, Mr Mark says he can measure better than our police officer. Mr. Mark says he consistantly performs land surveys accurate to 1/100th of a foot.
Well I know a metrologist at our local particle accelerator that can measure down to a micron.
Bet then, your honor, we aren't here to compare Johnson's.
We can show that whether the skid mark is 299 feet or 301 feet long that it doesn't matter when we are assuming the car weight before the accident, the friction factor between the tire and the pavement and more things.
What it basically comes down to is Mr. Mark wants to tell us that he can measure to 1/100th of a foot. Well, good for him. We concede while he isn't the best "measurer" in the world, he is a better "measurer" than our officer. He hasn't demonstrated that he knows squat about forensic reconstruction.
Our crash investigator has 20 plus years doing this. And his name is Johnson.
Cliff Mugnier and I have seen forensic cases where people sure wished after Daubert hearings that they'd have calibrated or checked their instruments.
Point of thread was to ask a question, and I am disappointed that you have degraded it to the point of calling what someone says "stupid." Thanks much, to the rest of you....plenty of room for thought.
My thinking, after reading all of this is that the state employee surveyors don't have to be registered here in Louisiana, so it might bleed over to the State Police. Credibility could become the issue in court, and if one does not have a good checked instrument, such as EDM, vertical circle indexing, good procedures, redundancy where necessary. Trust me, this is not stupid. Surveyors are probably the best professionals to make survey measurements in my mind. Many cases require extreme vertical tightness for hydroplaning, etc., and I would think a surveyor would be best for that. Personally, I think it is not wise to assume in a court case whether a precision of one foot in about 300 feet would would be precise enough. Juries sometimes do not understand significant figures, and I don't feel that it is very wise to fool around with slack in numbers when you don't have to, and I'd be calling myself stupid if I went out and measured something with an S6 to the nearest foot. The playing around with the signficant figures ought to be done more in the professions of figuring physics and engineering of the accident, and the surveys ought to be done as accurate as practicable--by a land surveyor in my opinion.
There is a draw back to NOT having Law Enforcement do the Accident Survey. They usually only do them at FATAL ACCIDENTS. Sometimes at Homicide Scenes. The work can be very emotionally demanding. Most especially if young children are involved as fatalities. I know of men who have seen terrible scenes and not even blink, cry like a baby when a baby is one of the victims. Most people are not really able to handle the stress.
SJ
Angelo thank you for that. I do not get what the big deal is either.
Some Accident Survey Humor - True story
Back in 1983 I worked for a guy who did a lot of accident surveys. They were not the ones the police do just after the accident, these surveys were at times years after an accident, done because of a lawsuit against a car manufacturer over some defect in the car that someone blamed the accident on.
We flew out to Arizona one early morning, three of us. My boss and a chainman. The mechanical engineer who was to accompany us met us at the airport and the four of us drove out to the accident site.
It was beastly hot. Were on the side of some highway in the desert. We establish some control aqnd start shooting scratches, gouges, paint lines, paving edges etc.
My boss and the mechanical engineer got into an argument over who should keep the notes. The mechanical engineer argued better, so my boss told him in a huffy voice that he was making a note in his field notes about it. (Humor one)
So after the main part of the work was done, the scratches, gouges, paint lines, paving edges, it's time to locate nuts and bolts. (Humor two) The mechanical engineer would locate a bolt or nut, the rodman would hold the prism pole, I would read the horizontal angle to my boss and the distance to the glass. Then the mechanical engineer would use his micrometer to get measurements and note it down in his book, as would my boss since he was still fuming over the note keeping thing.
Now, these shots were maybe 25 feet away max. for the nuts and bolt part of the survey. The rodman was weaving cause of the heat and I started handing out the horizontal angles to minutes. After about 10 of these minute readings my boss looks at me and says "You're rounding out to minutes..right?" I affirmed his suspicions and was duly chastened to read the seconds as well. After all, it's like 110°, the rodman is NO WAY holding that rod plumb, shots 10-25 feet away and I get chewed out for rounding to minutes. (Humor three)
Ok..day is long..we are exhausted but we finish and fly back into LA.
The next day I start drawing this pig up. Five scale...ever work at a five scale? It sucks. Map is like 12 feet long...sheesh!
I am doing these contours and grab a triangle and start connecting the tic marks. "No No" I am told. "Straight edge contours are only done for design, not for existing" So now I have to connect the tic marks freehand. (Humor four)
I finish the map and it gets mailed out.
A few days later the mechanical engineer calls up and wants to ask about something on the map, so I get on the phone and he says "I noticed that in one area the contours seem to wiggle a bit and then straighten out, are these representing dune ripples in the sand?" (Humor five)
I tell him Nope, thats where my hand jerked when I was freehanding the contours on that 12 foot pig of a map.
He thanks me for the clarification and says Goodbye.
Mark
"There is a boatload of money and frequently someones freedom and future at stake over these investigations. It is very important that they get done right. This isn't akin to hammering in a nail."
Are you suggesting that the only person who can operate a total station, collect data, download it into a CAD program and present it in an orderly, accurate fashion is a Professional Land Surveyor? Let's be realistic here.
Take it into another realm......do you need a licensed land surveyor to lay out a baseball field or a football gridiron?
How about determining the yardage on a golf course, or distance results for discus or javelin throws at a track and field meet?
Mark
> Are you suggesting that the only person who can operate a total station, collect data, download it into a CAD program and present it in an orderly, accurate fashion is a Professional Land Surveyor? Let's be realistic here.
Yes, I am. Or rather, while it is possible for someone to collect and present accurate data without being licensed - just as it may be possible for a person to be an excellent surgeon without being a licensed doctor - the only way to insure that the work is done in a professional manner is to have a professional supervising the work.
>
> Take it into another realm......do you need a licensed land surveyor to lay out a baseball field or a football gridiron?
> How about determining the yardage on a golf course, or distance results for discus or javelin throws at a track and field meet?
Both teams play on the same field, so the effect of any mis-measurement is mitigated. IN any case, these are games. Nobodies freedom is at stake in this example.
> Mark Please tell us what difference one foot makes in the difference for a speed/stopping calculation.
>
I have no idea. I submit that it may be significant. Some years ago my son was involved in an accident where a garbage truck pulled out in front of him. The speeds involved where comparatively low, in the 25-30 mph range. The skid marks were well under 50 feet long. A difference of a foot there would be a big deal. Furthermore, it involved different surfaces (a level railroad crossing with a rubber mat sort of material), driveway accesses, a center median strip, traffic patterns at an intersecting street, and a changing grade (cresting at the railroad). A lot more than taping the length of a single skid mark. My son had injuries that took some time and therapy to recover from and he continues to have issues he will be dealing with for life, to say nothing of a totalled car and damaged garbage truck. A lot of money was involved here - way more than the cost of a survey.
And it is quite possible for mis-managed data to get fouled up far beyond a foot. I recently did a survey where an earlier surveyor had fouled up a measurement by some 70 feet - where the true measurement was about 10 feet.
Bottom line, if you do not think that professional supervision is appropriate for an accident scene investigation survey please explain why it is necessary for a survey of a boundary. There may well be more at stake with the former.
I agree completely. Good point, and very unfortunate circumstances. And we all know that vertical tolerance is important too, especially in hydroplaning accidents.
A professional doing forensic calculations is the one who should be the one to take the liberty of rounding off numbers or required precision and/or accuracy in what he uses. The field measurements should be taken as accurately as practicable though. A series of rounding errors (surveyor and also the engineer calculating the forensics in succession)can result in something that may be farther out of whack than intended. Not telling you surveyors anything you don't already know. My problem is that some of the field measurers may not know this, and may not understand importance the measurements, good techniques,and checking.
Stephen
You are so right about that. One in particular, a hydroplaning accident, and a small girl about 12 makes me sick everytime I think about it. You'd better believe that the measurements I did on that one were as accurate as I could possibly make them. I guess police and others get a lot more hardened to this kind of stuff, or at least they can control their thinking better at these types of scenes.
"...Bottom line, if you do not think that professional supervision is appropriate for an accident scene investigation survey please explain why it is necessary for a survey of a boundary. There may well be more at stake with the former..."
I believe crime scene investigators are professional and provide supervision on site.
"...The field measurements should be taken as accurately as practicable though..."
I agree. And in most cases forensic investigators, and courts, believe the forensic investigator provides practicable accuracey.
> I believe crime scene investigators are professional and provide supervision on site.
The State of Oregon agrees with you, Mike. I don't. What is important is whether a jury of peers agrees with you after a really good cross examination.
I am just glad to know my local police are outsourcing all of the traffic enforcement operations to for profit camera companies so they can get out in the field and survey.
