View source for 4.2 Network Skims

[[Category:4.0 Directory & Data Structures]]

<p class="BodyParagraph">Highway and transit skims are created by Visum skimming procedures. These are then used as inputs by DaySim during day pattern simulation.</p><h3 id="id-4.2NETWORKSKIMS-HighwaySkims"><span style="color: rgb(255,102,0);">Highway Skims</span></h3><p class="BodyParagraph">The skims generated by the Calculate PrT skim matrix procedure are stored in the Visum version file. These are then exported into the format required for DaySim by the ''export_all_hwy_skims.py'' and ''export_{period}_hwy_skims.py'' Python scripts.</p><p class="BodyParagraph">DaySim requires skim files in text format which are created in a step in “DaySim” application. All the skim files are output to the following folder: Master\{SCENARIO_DIR}\Output\DaySim\.</p><p class="BodyParagraph">Following are highway skim files created: SKM_AM_D1.TXT, SKM_AM_S2.TXT, SKM_AM_S3.TXT, SKM_MD_D1.TXT, SKM_MD_S2.TXT, SKM_MD_S3.TXT, SKM_PM_D1.TXT, SKM_PM_S2.TXT, SKM_PM_S3.TXT, SKM_EV_D1.TXT, SKM_EV_S2.TXT, SKM_EV_S3.TXT. All the files are space-delimited and do not have any headers. Table 4‑1 shows the structure of the files.</p><h4 class="BodyParagraph" id="id-4.2NETWORKSKIMS-TABLE4-1HIGHWAYSKIMFILEFORMAT">TABLE 4-1 HIGHWAY SKIM FILE FORMAT</h4><div class="table-wrap">
{|  class="wikitable" 
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Column #</strong></p>
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Name</strong></p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">1</p>
|  class="confluenceTd" | <p class="TableText">Origin TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">2</p>
|  class="confluenceTd" | <p class="TableText">Destination TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">3</p>
|  class="confluenceTd" | <p class="TableText">Time (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">4</p>
|  class="confluenceTd" | <p class="TableText">Distance (miles)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">5</p>
|  class="confluenceTd" | <p class="TableText">Cost ($)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">6</p>
|  class="confluenceTd" | <p class="TableText">Crossriver</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">7</p>
|  class="confluenceTd" | <p class="TableText">Intra-county factor</p>
|}</div><p class="BodyParagraph">SKM_NM.TXT is the non-motorized modes skim file. DaySim uses free flow shortest path distance with an average time of 20 minutes per mile for walk and 6 minutes per mile for bike.</p><h4 id="id-4.2NETWORKSKIMS-TABLE4-2NON-MOTORIZEDSKIMFILEFORMAT">TABLE 4-2 NON-MOTORIZED SKIM FILE FORMAT</h4><div class="table-wrap">
{|  class="wikitable" 
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Column #</strong></p>
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Name</strong></p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">1</p>
|  class="confluenceTd" | <p class="TableText">Origin TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">2</p>
|  class="confluenceTd" | <p class="TableText">Destination TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">3</p>
|  class="confluenceTd" | <p class="TableText">Time bike  (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">4</p>
|  class="confluenceTd" | <p class="TableText">Distance bike  (miles)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">5</p>
|  class="confluenceTd" | <p class="TableText">Time walk  (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">6</p>
|  class="confluenceTd" | <p class="TableText">Distance walk  (miles)</p>
|}</div><h3 id="id-4.2NETWORKSKIMS-TransitSkims"><span style="color: rgb(255,102,0);">Transit Skims</span></h3><p class="BodyParagraph">Transit skims are generated for peak (PK) and off-peak (OK) periods and six path types (bus, project mode, pnr-bus, pnr-project, knr-bus, and knr-project). It must be noted that even though skims are generated for PNR and KNR path types, DaySim only used walk access skims. It automatically determines the PNR/KNR station for a drive transit trip and obtains the skim value for the drive portion from highway skims files. The files can be found in Master\{{SCENARIO_DIR}\Output\DaySim\ - PK_WalkBus.TXT, PK_WalkCR.TXT, OK_WalkBus.TXT, and OK_WalkCR.TXT. It should also be noted that for now, project mode is considered to be commuter rail (CR). Columns in the transit skims files are shown in Table 4‑3. </p><h4 id="id-4.2NETWORKSKIMS-TABLE4-3TRANSITSKIMFILEFORMAT">TABLE 4-3 TRANSIT SKIM FILE FORMAT</h4><div class="table-wrap">
{|  class="wikitable" 
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Column #</strong></p>
|  class="highlight-red confluenceTd" data-highlight-colour="red" | <p class="TableHeadingGray"><strong>Name</strong></p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">1</p>
|  class="confluenceTd" | <p class="TableText">Origin TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">2</p>
|  class="confluenceTd" | <p class="TableText">Destination TAZ</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">3</p>
|  class="confluenceTd" | <p class="TableText">In-Vehicle Time (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">4</p>
|  class="confluenceTd" | <p class="TableText">Initial Wait Time (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">5</p>
|  class="confluenceTd" | <p class="TableText">Transfer Wait Time (min)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">6</p>
|  class="confluenceTd" | <p class="TableText">Fare (cents)</p>
|- 
|  class="confluenceTd" | <p align="center" class="TableText">7</p>
|  class="confluenceTd" | <p class="TableText">Number of boardings</p>
|}</div>