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Feature Class for Anne Arundel County snow map Hills.
Densify in QGIS to create 100 meter segments of all AA County streets... 70660 records in the Streets shp after this step.
2017 DEM used.
Input 100m Streets and 2017 DEM into ArcGIS 3D Analyst > Add Surface > produces Avg Slope for all 100m road segments.
Checked using basic slope formula: ( [Z_Max] - [Z_Min]) / [Shape_len] *100.
Google Street View and Pictometry's Ground Slope also used to check slope accuracy.
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Methodology used for false positives with bridges and DEM: Select by location all streets that intersect Bridges_and_Overpasses.shp.
From this selection, now select all the ones with slopes greater than 3.5.
In this selection, change all selected's Avg_Slope to 2... these are the more or less flat bridges that have 2% with +- 1% discrepancies.
Used Google / Bing Street Views and Pictometry's Ground Slope to spot check about 50 of them and all looked correct.
County maintained roads were extracted out.
Known caveats: Where new streets have been planned but not built yet (or built after 2017) there will be erroneous slope values.
Bridges and overpasses produce false positives. Work around by setting all of them to slope = 2% which results in +- 1% discrepancies in most cases.
Some of the smaller bridges (not listed in the Bridges shp) were not accounted for e.g. Buckingham Place, Patuxent River Rd, etc.
There are a few errors in the Bridges shp that result in "select by location" missing the target e.g. Conway Road at Little Patuxent 6.
"Shoreline" values in Streams shp produced a few oddities in the cold spot streets. |
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Feature Class for Anne Arundel County snow map Hills.
Densify in QGIS to create 100 meter segments of all AA County streets... 70660 records in the Streets shp after this step.
2017 DEM used.
Input 100m Streets and 2017 DEM into ArcGIS 3D Analyst > Add Surface > produces Avg Slope for all 100m road segments.
Checked using basic slope formula: ( [Z_Max] - [Z_Min]) / [Shape_len] *100.
Google Street View and Pictometry's Ground Slope also used to check slope accuracy.
-------------------------------------------------------
Methodology used for false positives with bridges and DEM: Select by location all streets that intersect Bridges_and_Overpasses.shp.
From this selection, now select all the ones with slopes greater than 3.5.
In this selection, change all selected's Avg_Slope to 2... these are the more or less flat bridges that have 2% with +- 1% discrepancies.
Used Google / Bing Street Views and Pictometry's Ground Slope to spot check about 50 of them and all looked correct.
County maintained roads were extracted out.
Known caveats: Where new streets have been planned but not built yet (or built after 2017) there will be erroneous slope values.
Bridges and overpasses produce false positives. Work around by setting all of them to slope = 2% which results in +- 1% discrepancies in most cases.
Some of the smaller bridges (not listed in the Bridges shp) were not accounted for e.g. Buckingham Place, Patuxent River Rd, etc.
There are a few errors in the Bridges shp that result in "select by location" missing the target e.g. Conway Road at Little Patuxent 6.
"Shoreline" values in Streams shp produced a few oddities in the cold spot streets. |
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Created by Paul Russel, GIS Technician in DPW Technical Engineering, in May 2019. Methodology approved by Carl Converso, Road Operations Supervisor. |
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<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Feature Class for Anne Arundel County snow map Hills (Avg_Slope >= 9.0.)</SPAN></P></DIV></DIV></DIV> |
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<DIV STYLE="text-align:Left;"><P><SPAN STYLE="font-weight:bold;">Disclaimer</SPAN></P><P><SPAN>While efforts have been made to ensure the accuracy of this data, Anne Arundel County accepts no liability or responsibility for errors, omissions, or positional inaccuracies in the content of this data. Reliance on this data is at the risk of the user. This data is for illustration purposes only and should not be used for surveying, engineering, or site-specific analysis. For additional information view the </SPAN><A href="https://www.aacounty.org:443/county-maps/data-download/GIS_Disclaimer.pdf" STYLE="text-decoration:underline;"><SPAN>GIS Disclaimer</SPAN></A><SPAN>.</SPAN></P></DIV> |
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| title:
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Highways.SDELOADER.Hills |
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["Anne Arundel County","Department of Public Works","Bureau of Highways","DPW","BOH","Snow","Hills"] |
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en-US |
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500000 |
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