CPT Comparing Sub-reaches within a Single Navigation Project

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A typical USACE deep-draft navigation project, such as Charleston Harbor or the Sabine-Neches Waterway, will contain many miles of maintained channels. In a limited funding environment, the challenge presented to Corps management during each budget cycle is how to allocate Operations and Maintenance (OM) funding such that the most critical (in terms of both utilization and condition) sub-reaches within projects are given priority for dredging while less critical portions are deferred until additional funds are made available. CPT was designed to address this issue, and the following sections will show how to go about prioritizing sub-reaches within a project for OM funding, using Charleston Harbor, S.C. as an example.

Selecting sub-reaches

As described in Section 2.2 Selection of items to be ranked and/or analyzed, the reaches to be compared are chosen after selecting the Reaches analysis level on the CPT Home screen. Figure 11 shows the reaches with the Charleston Harbor Project being selected.

Fig. 11 – Selection of Reaches within Charleston Harbor, SC

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Note that a prompt appears indicating when all reaches within the Project have been selected. The next step is to set query preferences.

Setting Preferences

As covered in Section 2.3 Explanation of Preferences, the Preferences tab should be selected once all of the reaches that are to be compared have been chosen. In Figure 11, the Preferences tab is located immediately to the right of the highlighted Reach Selection tab. Once selected, the Preferences can be set according to user specifications. For the purposes of this example with Charleston Harbor, leave all Preferences set to the default selections (Ignore Shoaling checked, All Movements checked, Transiting tonnage mode selected, all commodities included) except for the Years setting, which should be set to 2007 only in order to improve query times, as shown in Figure 12. Note that the All Years box must first be unchecked before the year menu becomes active. Once the desired year has been highlighted, clicking the Save Preferences button will confirm the query settings.

Fig. 12 – Specifying single year of coverage on Preferences page

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Viewing Rankings tables

With the Preferences saved and the CPT window confirming this as shown in Figure 10, proceed to the Rankings page by clicking on the tab immediately to the right of the highlighted Preferences tab. Figure 13 shows the Rankings page that should result for this example with Charleston Harbor.

Fig. 13 – CPT Tonnage Rankings for Reaches in Charleston Harbor, SC for 2007

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Note that by default the reaches are ranked in terms of tons, but that a second column containing the $-value of tonnage in each reach is also included. The reaches can be ranked in terms of $-value of cargo by simply clicking on the Dollars column. Figure 14 shows the re-ordering of reaches when ranked by $-value instead of tons.

Fig. 14 – CPT $-value Rankings for Reaches in Charleston Harbor, SC for 2007

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The reaches can be sorted in either descending (default) or ascending order, in terms of both tons or $-value, by clicking on the Tons and Dollars column labels, respectively. Note that only the first 10 reaches are shown initially, but that the number shown can be expanded using the small drop-down box shown below the rankings table.

Exporting Rankings tables to Microsoft Excel

The Rankings table can be written to a Microsoft Excel spreadsheet file for subsequent viewing and processing by using the Export to Excel button found at the bottom-left of the Rankings page (see Figure 14). Appearances will vary depending on web browser type and settings, but a prompt should appear giving the user the option of saving the file or launching Excel and opening the file directly. Figure 15 shows an example using Mozilla Firefox.

Fig. 15 – User prompt shown when Export to Excel option chosen

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Figure 16 shows the Microsoft Excel spreadsheet once exported and opened for viewing.

Fig. 16 – Microsoft Excel spreadsheet showing ranked reaches in Charleston Harbor, SC

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Exporting to and viewing of Rankings in Google Earth

The results of the rankings query may also be exported to Google Earth to help visualize the relative significance of each reach. This is done by selecting the Export to KML button found just below the previously discussed Export to Excel button (see Figs. 13-15). As with the spreadsheet option, once selected, a user prompt will appear giving the option of saving the results as a .kml file for later viewing or launching Google Earth and viewing the results directly. Figure 17 shows this prompt as it appears in Mozilla Firefox.

Fig. 17 – User prompt shown when Export to KML option is chosen

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The actual format of the resulting Google Earth overlay file will depend upon the KML settings previously defined on the Preferences page (Section 2.3.6 Google Earth .kml settings). The default settings are shown for the Charleston Harbor example in Figure 18.

Fig. 18 – Charleston Harbor Reach Rankings visualization in Google Earth

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The width of each polygon represents the total tons utilizing the respective reach within Charleston Harbor. The polygon overlays representing each reach are fully interactive within the Google Earth environment, and can be clicked on to reveal the respective reach name, tons, and $-value (these values should match the figures seen in the Rankings table). The color scheme is intended only to help differentiate the separate reaches, and has no connection to the reach in terms of tons or $-value.

Viewing Rankings charts and saving to file or to clipboard

Scrolling down the Rankings page below the table and export buttons, two charts can be seen which offer another visualization of the relative significance of each reach in terms of tons and $-value of cargo. Figs. 19 and 20 show the tons and $-value charts, respectively, for the Charleston Harbor example.

Fig. 19 – Rankings bar chart showing tons for reaches in Charleston Harbor, SC, 2007

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Fig. 20 – Rankings bar chart showing $-value for reaches in Charleston Harbor, SC, 2007

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In all cases, the charts may be either saved to file or copied to the clipboard by right clicking within the chart area and selecting the desired option.