Merge pull request google#276 from MobilityData/bidirectional-fare-gates

Allow fare gates (pathway_mode=6) to be bidirectional

gtfs/spec/en/reference.md

@@ -359,7 +359,7 @@ Pathways must be defined exhaustively in a station. If any pathways are defined,
 |  `from_stop_id` | ID referencing `stops.stop_id` | **Required** | Location at which the pathway begins.<br><br>Must contain a `stop_id` that identifies a platform (`location_type=0` or empty), entrance/exit (`location_type=2`), generic node (`location_type=3`) or boarding area (`location_type=4`).<br><br> Values for `stop_id` that identify stations (`location_type=1`) are forbidden.|
 |  `to_stop_id` | ID referencing `stops.stop_id` | **Required** | Location at which the pathway ends.<br><br>Must contain a `stop_id` that identifies a platform (`location_type=0` or empty), entrance/exit (`location_type=2`), generic node (`location_type=3`) or boarding area (`location_type=4`).<br><br> Values for `stop_id` that identify stations (`location_type=1`) are forbidden.|
 |  `pathway_mode` | Enum | **Required** | Type of pathway between the specified (`from_stop_id`, `to_stop_id`) pair. Valid options are: <br><br>`1` - Walkway. <br>`2` - Stairs. <br>`3` - Moving sidewalk/travelator. <br>`4` - Escalator. <br>`5` - Elevator. <br>`6` - Fare gate (or payment gate): A pathway that crosses into an area of the station where proof of payment is required to cross. Fare gates may separate paid areas of the station from unpaid ones, or separate different payment areas within the same station from each other. This information can be used to avoid routing passengers through stations using shortcuts that would require passengers to make unnecessary payments, like directing a passenger to walk through a subway platform to reach a busway. <br>`7`-  Exit gate: A pathway exiting a paid area into an unpaid area where proof of payment is not required to cross.|
-|  `is_bidirectional` | Enum | **Required** | Indicates the direction that the pathway can be taken:<br><br>`0` - Unidirectional pathway that can only be used from `from_stop_id` to `to_stop_id`.<br>`1` - Bidirectional pathway that can be used in both directions.<br><br>Fare gates (`pathway_mode=6`) and exit gates (`pathway_mode=7`) must not be bidirectional.|
+|  `is_bidirectional` | Enum | **Required** | Indicates the direction that the pathway can be taken:<br><br>`0` - Unidirectional pathway that can only be used from `from_stop_id` to `to_stop_id`.<br>`1` - Bidirectional pathway that can be used in both directions.<br><br>Exit gates (`pathway_mode=7`) must not be bidirectional.|
 | `length` | Non-negative float | Optional | Horizontal length in meters of the pathway from the origin location (defined in `from_stop_id`) to the destination location (defined in `to_stop_id`).<br><br>This field is recommended for walkways (`pathway_mode=1`), fare gates (`pathway_mode=6`) and exit gates (`pathway_mode=7`).|
 | `traversal_time` | Positive integer | Optional | Average time in seconds needed to walk through the pathway from the origin location (defined in `from_stop_id`) to the destination location (defined in `to_stop_id`).<br><br>This field is recommended for moving sidewalks (`pathway_mode=3`), escalators (`pathway_mode=4`) and elevator (`pathway_mode=5`).|
 | `stair_count` | Non-null integer | Optional | Number of stairs of the pathway.<br><br>A positive `stair_count` implies that the rider walk up from `from_stop_id` to `to_stop_id`. And a negative `stair_count` implies that the rider walk down from `from_stop_id` to `to_stop_id`.<br><br>This field is recommended for stairs (`pathway_mode=2`).<br><br>If only an estimated stair count can be provided, it is recommended to approximate 15 stairs for 1 floor.|