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| # Case 2: Pedestrian / bicycle access to destinations on a node-link network | ||
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| This use case requires node-link network that includes both streets and relevant off-road paths. It models access to destinations for pedestrian and bicycls condidering link availability, distannce, and some mesasure of traffic stress. This is the model for the Cambridge Multimodal Network [example](https://github.com/zephyr-data-specs/GMNS/tree/develop/examples/Cambridge_Multimodal_Network) | ||
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| The config table is needed because it contains the units for the other tables, as well as the coordinate reference system (CRS) | ||
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| Table Config table for case 2 | ||
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| | **name** | **type** | **description** | **needed** | **comment** | | ||
| | --- | --- | --- | --- | --- | | ||
| | dataset_name | any | Name used to describe this GMNS network | Yes | | | ||
| | short_length | any | Length unit used for lane/ROW widths and linear references for segments, locations, etc. along links | Maybe | Needed if sidewalk or bike lane/path width is part of the evaluation | | ||
| | long_length | any | Length unit used for link lengths | Yes | Typically, miles or km | | ||
| | speed | any | Units for speed. Usually long_length units per hour | Yes | Typically, mph or kph | | ||
| | crs | any | Coordinate system used for geometry data in this dataset. Preferably a string that can be accepted by pyproj (e.g., EPSG code or proj string) | Yes | Typically, WGS 84 (EPSG:4326) | | ||
| | geometry_field_format | any | The format used for geometry fields in the dataset. For example, WKT for files stored as plaintext | Yes | Typically, wkt | | ||
| | currency | any | Currency used in toll fields | No |Presumably, bike and ped facilities do not have tolls | | ||
| | version_number | number | The version of the GMNS spec to which this dataset conforms | Yes | | | ||
| | id_type | string | The type of primary key IDs for interopability (node_id, zone_id, etc.). May be enforced by user, database schema, or downstream software. Must be either string or integer. | {'enum': \['string', 'integer'\]} | Depends on whether the routing software needs primary keys of a particular type | | ||
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| The node table is needed because it locates the network on the Earth and indicates how links are connected. | ||
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| Table Node table for case 2 | ||
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| | **name** | **type** | **description** | **needed** | **comments** | | ||
| | --- | --- | --- | --- | --- | | ||
| | node_id | any | Primary key | Yes | | | ||
| | name | string | | No | | | ||
| | x_coord | number | Coordinate system specified in config file (longitude, UTM-easting etc.) | Yes | To locate the nodes on a map | | ||
| | y_coord | number | Coordinate system specified in config file (latitude, UTM-northing etc.) | Yes | To locate the nodes on a map | | ||
| | z_coord | number | Optional. Altitude in short_length units. | No | This example network is fairly flat. z_coord could be used if modeling hilly terrain | | ||
| | node_type | string | Optional. What it represents (intersection, transit station, park & ride). | Maybe | Depends on the routing algorithm. Some may require centroid nodes to be labeled as such. | | ||
| | ctrl_type | string | Optional. Intersection control type - one of ControlType_Set. | Maybe | Not used in this example. Could be used if control_type (signal, stop, etc) is important for the routing algorithm | | ||
| | zone_id | any | Optional. Could be a Transportation Analysis Zone (TAZ) or city, or census tract, or census block. | No | | | ||
| | parent_node_id | any | Optional. Associated node. For example, if this node is a sidewalk, a parent_nodek_id could represent the intersection it is associated with. | No | | | ||
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| The link table is needed for routing. It contains several user defined fields, beginning with u_, used to calculate the bicycle and pedestrian impedance, | ||
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| Table Link table for case 2 | ||
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| | **name** | **type** | **description** | **needed** | **comments** | | ||
| | --- | --- | --- | --- | --- | | ||
| | link_id | any | Primary key - could be SharedStreets Reference ID | Yes | | | ||
| | name | string | Optional. Street or Path Name | Yes, for some | Used to identify the major roads | | ||
| | from_node_id | any | Required. Origin Node | Yes | | | ||
| | to_node_id | any | Required. Destination Node | Yes | | | ||
| | directed | boolean | Required. Whether the link is directed (travel only occurs from the from_node to the to_node) or undirected. | Yes | | | ||
| | geometry_id | any | Optional. Foreign key (Link_Geometry table). | Maybe | | | ||
| | geometry | any | Optional. Link geometry, in well-known text (WKT) format. Optionally, other formats supported by geopandas (GeoJSON, PostGIS) may be used if specified in geometry_field_format in gmns.spec.json | Maybe | Either geometry_id or geometry is needed if the links are to be displayed using true shapes (and not as a stick network). | | ||
| | parent_link_id | any | Optional. The parent of this link. For example,for a sidewalk, this is the adjacent road. | No | Not used in this example, but could be used to associate sidewalks with their adjacent streets | | ||
| | dir_flag | integer | Optional. <br>1 shapepoints go from from_node to to_node; <br>\-1 shapepoints go in the reverse direction; <br>0 link is undirected or no geometry information is provided. | No | | | ||
| | length | number | Optional. Length of the link in long_length units | Yes | Can by computed by the GIS based on the geometry | | ||
| | grade | number | % grade, negative is downhill | No | Could be useful in a hilly network | | ||
| | facility_type | string | Facility type (e.g., freeway, arterial, etc.) | Yes | Since few links had directly-measured traffic volumes, facility_type was used as a proxy for traffic volume, as an input to the traffic stress calculation | | ||
| | capacity | number | Optional. Saturation capacity (passenger car equivalents / hr / lane) | No | Refers to motor vehicle capacity. Assuming bike/ped is uncapacitated | | ||
| | free_speed | number | Optional. Free flow speed, units defined by config file | Maybe | Motor vehicle speed, could go into the traffic stress computation | | ||
| | lanes | integer | Optional. Number of permanent lanes (not including turn pockets) in the direction of travel open to motor vehicles. It does not include bike lanes, shoulders or parking lanes. | Yes | Motor-vehicle lanes could go into the traffic stress computation | | ||
| | bike_facility | string | Optional. Types of bicycle accommodation based on the National Bikeway Network Data Template (Table 1-A at https://nmtdev.ornl.gov/assets/templates/NBN_DataTemplates_final.pdf) | Yes | Important for this example | | ||
| | ped_facility | string | Optional. Type of pedestrian accommodation: unknown, none, shoulder, sidewalk, offstreet path | No | | | ||
| | parking | string | Optional. Type of parking: unknown, none, parallel, angle, other | Yes | Important for this example | | ||
| | allowed_uses | string | Optional. Set of allowed uses that should appear in either the use_definition or use_group tables; comma-separated. | Yes | Indicates whether bicycles or pedestrians can use the link at all | | ||
| | toll | number | Optional. Toll on the link, in currency units. | No | No tolls in this network | | ||
| | jurisdiction | string | Optional. Owner/operator of the link. | No | | | ||
| | row_width | number | Optional. Width (short_length units) of the entire right-of-way (both directions). | No | | | ||
| | u_bike_speed | number | User defined. Average bicycle speed as adjusted depending on the attractiveness of the facility | Yes | More attractive facilities are "faster", less attractive are "slower". Sidewalks, where bikes may be walked, are given a walking speed | | ||
| | u_walk_speed | number | User defined. Average walking speed as adjusted depending on the attractiveness of the facility | Yes | More attractive facilities are "faster", less attractive are "slower". | | ||
| | u_bike_travel_time | number | User defined. Calculated based on speed and link length. | Yes | Used by the GIS accessibility calculator | | ||
| | u_walk_travel_time | number | User defined. Calculated based on speed and link length. | Yes | Used by the GIS accessibility calculator | | ||
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