Conveyance 
Conveyance features to be identified and inventoried include actual, physical features (pipes and ditches) and database connectivity features (hydraulic connectors). Conveyance is represented as line features in the database. Although they do not physically exist, hydraulic connectors should be inventoried to facilitate connection of drainage systems through stormwater BMPs; this is the only case where a hydraulic connector is created. Not every pipe or ditch conveyance is inventoried, but generally all conveyances between structures are inventoried. Conveyance features will have an upstream and downstream structure. When contract plans are not available showing proper conveyance for a storm drain system, conveyance can be determined by looking at the pipe(s) direction inside of structures. Field crews are not required to open manhole lids, and conveyance can be assumed at the field crew’s discretion when plans are not available. 
 
Pipes, Cross Culverts, & Driveway Culverts
Pipes connect structures together in a system to maintain conveyance. Pipes consist of closed storm drain pipes, cross culverts, and driveway culverts. Rules for collecting cross culvert and driveway culvert pipes are described below. The following are rules that should be followed when collecting pipes within the storm drain network:
All pipes between closed storm drain structures are inventoried.
Pipes less than five feet in height are inventoried within SHA ROW. 

Pipes that are greater than five feet in height are not inventoried if they do not connect to closed storm drain structures. 
Pipes that are greater than five feet in height and do connect to closed storm drain structures are inventoried with the storm drain network.
Closed storm drain systems that outfall through a pipe or culvert that is greater than five feet in height are inventoried. 
 
Pipe size, shape, invert, and material are recorded for all pipes. Because field crews are not required to open grates or manhole lids, this attribute information is most often gathered from contract plans. Pipe sizes and material should be verified in the field by observation through inlet grates and at end structures (headwalls, end sections, outfalls, projection pipes). Field crews should become familiar with different pipe sizes and materials prior to conducting field inventory. 
 
Cross Culverts are pipes, boxes, or arches that convey water from one side of the ROW to the other side, usually under the roadway. Cross culverts are inventoried as pipes. Depending on the situation and culvert size, not all cross culverts will be inventoried. The following are rules that should be followed when collecting cross culverts:
The culvert height is determined from contract plans when available. Otherwise care should be taken to measure and estimate the actual culvert height in the field. This may require estimating the depth of sedimentation at the culvert ends to determine the feet of buried culvert. 

For more information, contact MDOT SHA OIT Enterprise Information Services:  
Email: GIS@mdot.maryland.gov 

Last Published: 11/06/2019, 
Publisher: J.Lloyd (jlloyd@mdot.maryland.gov)
Conveyance
Conveyance features to be identified and inventoried include actual, physical features (pipes and ditches) and database connectivity features (hydraulic connectors). Conveyance is represented as line features in the database. Although they do not physically exist, hydraulic connectors should be inventoried to facilitate connection of drainage systems through stormwater BMPs; this is the only case where a hydraulic connector is created. Not every pipe or ditch conveyance is inventoried, but generally all conveyances between structures are inventoried. Conveyance features will have an upstream and downstream structure. When contract plans are not available showing proper conveyance for a storm drain system, conveyance can be determined by looking at the pipe(s) direction inside of structures. Field crews are not required to open manhole lids, and conveyance can be assumed at the field crew’s discretion when plans are not available.
 
Pipes, Cross Culverts, & Driveway Culverts
Pipes connect structures together in a system to maintain conveyance. Pipes consist of closed storm drain pipes, cross culverts, and driveway culverts. Rules for collecting cross culvert and driveway culvert pipes are described below. The following are rules that should be followed when collecting pipes within the storm drain network:
All pipes between closed storm drain structures are inventoried.
Pipes less than five feet in height are inventoried within SHA ROW.
Pipes that are greater than five feet in height are not inventoried if they do not connect to closed storm drain structures. 
Pipes that are greater than five feet in height and do connect to closed storm drain structures are inventoried with the storm drain network.
Closed storm drain systems that outfall through a pipe or culvert that is greater than five feet in height are inventoried. 
 
Pipe size, shape, invert, and material are recorded for all pipes. Because field crews are not required to open grates or manhole lids, this attribute information is most often gathered from contract plans. Pipe sizes and material should be verified in the field by observation through inlet grates and at end structures (headwalls, end sections, outfalls, projection pipes). Field crews should become familiar with different pipe sizes and materials prior to conducting field inventory.
 
Cross Culverts are pipes, boxes, or arches that convey water from one side of the ROW to the other side, usually under the roadway. Cross culverts are inventoried as pipes. Depending on the situation and culvert size, not all cross culverts will be inventoried. The following are rules that should be followed when collecting cross culverts:
The culvert height is determined from contract plans when available. Otherwise care should be taken to measure and estimate the actual culvert height in the field. This may require estimating the depth of sedimentation at the culvert ends to determine the feet of buried culvert.
[]
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