I've been sent these two photos from a traffic camera and I've been given an apparent speed (in mph) that the vehicle was going at. I would like to see if this could be double-checked mathematically, but I've been out of school for over a decade and my knowledge of the proper geometry equations and methods are lost to me. So, I turn to you guys to help both with the reminder of how this is calculated and to confirm the vehicle speed.
I've left the relevant information on the image; location, timestamp, full resolution that was provided.
Further relevant info:
-The time between the photos as shown is .4 seconds.
-The make and model of the vehicle is a Ford Focus SE which has a wheelbase of 8'8.3" (104.3")
-The road is in VA, and thankfully the standards for road markings are listed online. Virginia Supplement to the 2009 MUTCD - Revision 1
-On page 3-3 section 03 the VADOT states that broken line markings are 10' segments with 30' gaps between them.
[Photo 1]
[Photo 2]
INITIAL APPROXIMATION :
It looks like the Car back wheel has moved half-way from the tip of a white marking to the tip of the next white marking.
that is $(10+30)/2=20$
Possible time frame : maximum $xx:xx:xx.59999999999-xx:xx:xx.10000000001 \approx 0.5$
Possible time frame : minimum $xx:xx:xx.50000000001-xx:xx:xx.19999999999 \approx 0.3$
Possible time frame : median $xx:xx:xx.50000000001-xx:xx:xx.100000000001 \approx 0.4$
Hence :
$\text{MAX SPEED} = 20/0.3$
$\text{MIN SPEED} = 20/0.5$
$\text{AVG SPEED} = 20/0.4$
Converting to "mph" :
SPEED might be between $27.27$ & $45.45$ , generally around $34.01$
IMPROVEMENT :
(1) We have to measure the Distance between the front wheel Positions & make the calculations.
(2) We have to check whether Car was traveling at some angle & compensate.
(3) We have to ask for further Images & make calculations over longer Durations.
(4) We have to measure the length & width of the Car & using that measurement , we have to measure the road Distance.
(5) We have to measure the wheel movement more accurately via Imaging tools & trigonometry.
(6) We have to ask for Image Meta Data where the time measurement may have more Detail.
These might change the overall calculations by a little to give a narrower overall range.