Figure 5 <br />Branch <br />HotINEERING= <br />Since 1977 <br />October 5, 2o16 <br />Rick Satre <br />Schirmer Satre Group <br />375 W 4th Ave #201 <br />Eugene, OR 97401 <br />.,Received <br />OCT 05 2016 <br />RE: METRO PLAN ALIGNMENT City of Eugene <br />LAURELRIDGE ZONE CHANGE (Z 15-5) Planning Division <br />Branch Engineering Inc. Project No. 11-o68:2d <br />Dear Rick, <br />This letter provides information for your use when merging and/or comparing Branch <br />Engineering's survey data with data from other sources. The survey data referred to is our map <br />dated September 20, 2016 titled "Exhibit Map Laurel Ridge Zone Change (Z15-5)"• <br />Scaling Accuracy <br />When taking a measurement from a paper map, the effect of the drawing's scale needs to <br />be taken into consideration. A large scale drawing (such as 1"=20') will support more accurate <br />measurements than a small scale drawing (such as 1"=1000'). This is due to a number of probably <br />very obvious factors, the most important of which is the eye's ability to discern fine measurements. <br />In the context of the application submittals to date, this is relevant to both Mr. Schlieder's <br />assertion in his September 28, 2016 letter that I incorrectly scaled the pixels at 15' instead of 17.5' <br />and the city's measurement of 850' from site to city limits in their September 28, 2016 letter. <br />The city took measurements from a paper copy of "Zone Change: Subject Property", sheet <br />ZC-2, dated May 15, 2015. This drawing has a scale of 1"=200' which means that 1'=0.005". By <br />my measurements on this map, the property line scales as having a width of 15' and the city limits <br />line a width of 5'. It is well known that on the ground neither of these lines has a width so the first <br />potential for inaccuracy is estimating the center of the two lines. Once this is done to the best of <br />the person's ability, the second opportunity for inaccuracy arises: the resolution of the naked eye. <br />I do not know the scientifically accepted value for the resolution of the naked eye, but I have <br />personally never felt able to accurately identify a measurement of less than half of the distance <br />between ticks on an engineer's scale; for 1"=200' half the distance between ticks is 5'. <br />A similar conversation exists around the scaling of pixels from the drawing titled "Zone <br />Change: Metro Plan Diagram on Subject Prop", sheet ZC-4, dated May 15, 2015. The drawing has <br />a scale of 1"=200' which means that 1'=0.005". This is the same scale as the map discussed above. <br />As mentioned there, I do not know the scientifically accepted value for the resolution of the naked <br />eye; I rather doubt the naked eye can discern 0.0025" for the 0.5' accuracy Mr. Schlieder seems <br />to feel capable of. Put another way, Mr. Schlieder apparently feels able to accurately identify <br />EUGENE-SPRINGFIELD SALEM-KEIZER <br />310 5th Street, Springfield, OR 97477 1 p: 541.746.0637 1 f: 541.746.0389 1 www.branchengineering.com <br />