key aspects of navigation - direction of traffic flow (dtrf) 11
TRANSCRIPT
KEY ASPECTS OF NAVIGATION - Direction of Traffic Flow (DTRF)
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Definition
Direction of Traffic Flow (DTRF) is the direction traffic is allowed to travel on a road (or ferry).
Direction of Traffic Flow can be:– Open (open in both directions)
– One Way (open one direction, closed in the opposite direction)
– Closed (closed in both directions)
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Description
Direction of Traffic Flow Indicators– Traffic signs
• “One Way”
• “Do not enter”
– Painted arrows on road
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Description
Traffic signs may have: – Vehicle Type Restriction
– Time Related Info
6:30 to 9:00 AM
Except Busses
Direction of Traffic Flow
‘closed’ from 06:30 to 09:00
Direction of Traffic Flow
‘closed’ to all vehicles except busses
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Description
Consider both:– Legal meaning of sign– Exact location of the sign
Roads under construction:– DTRF for when construction is complete
A “Do not enter” sign at the end of a street does not always mean the street is one way. It may be posted so no-one will enter from that end of the street, while the street itself may remain open in both directions.
A ‘No Trucks’ sign posted on a road just after an alley that gives access to the delivery area for a set of stores should be captured at that location.
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DTRF - Rules
Traffic signs about direction of traffic flow must have an official & permanent nature.
Not permanent Not captured
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DTRF - Rules
If a traffic flow restriction applies for all roads in an area, the restriction must be captured for all captured Road Elements
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DTRF - Rules
Restricted Access Island: Do not capture restrictions in a way that some roads would be inaccessible to
vehicles, but vehicles would still be allowed to drive on them.
Correct attribution
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DTRF - Rules
Exact location of traffic sign Traffic flow can change in the middle of a street.
Add a node at the location of the sign to break the segment
A
BApply DTRF to the appropriate segment
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DTRF - Rules
Restrictive Time Domain: One road segment multiple DTRFs
– Restricted by Validity Period– Complementary– Not contradictory
School Zone
Road is one-way
6:30 to 07:30 AM
3:30 to 4:00 PM
Weekdays
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DTRF - Rules
Dead End Streets:
– Open in both directions
– Closed in both directions
– Never one-way
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DTRF - Rules
Dead End Streets: Can never one-way
Dead-end with Dead-end with one-waysone-ways
Impossible to Impossible to depart from nodedepart from node
Dead-end with Dead-end with one-waysone-ways
Impossible to Impossible to reach nodereach node
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DTRF - Rules
Traffic Circles (FOW 4) Must be one-way at all times
Clockwise & one-Clockwise & one-wayway
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DTRF - Rules
Limited access highway ramps Must be one-way
Separated streets Must be one-way
Walkways & Stepped Walkways Must be closed to all vehicular traffic
FRC 8 segments Must be closed to all vehicular traffic
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DTRF - Rules
Infinite Source All segments meeting at a node are one-way away from the node.
Infinite sourceInfinite source
Impossible to reach Impossible to reach (hidden) node(hidden) node
– Impossible to reach the node
– Not allowed in data
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DTRF - Rules
Infinite Sink All segments meeting at a node are one-way toward the node.
Infinite Infinite sinksink
Impossible to Impossible to depart from depart from
(hidden) node(hidden) node
– Impossible to depart the node
– Not allowed in data
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DTRF - Rules
Clockwise flow: If a node is met by three FRC-A segments
– with the same name– same z-level– and two of the segments are one-way
Then the two adjacent, 1-way segments
– must have clockwise flow at the node– (See next slide for example)
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DTRF - Rules
Clockwise flow:
One-ways have One-ways have clockwise flow clockwise flow
at the nodeat the node
One-ways have One-ways have counterclockwise counterclockwise flow at the nodeflow at the node
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DTRF - Rules
Capture minor roads:
A road where the one-way attribution changes from bi-directional to unidirectional at a driveway. Representing the driveway in the database allows the one-way attribution change to occur at a street valence-3 node instead of a street valence-2 node.
Driveway
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DTRF - Rules
.One-Way street connectors should be One-way
– unless there is indication otherwise
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DTRF - Rules
Ramp rungs Capture as open in both directions unless indicated otherwise in reality
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DTRF - Rules
Internal Turn Channels Segments internal to the square that makes up the intersection should be
open in both directions when there are opposing right turn channels (green segments
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DTRF - Rules
Internal Turn Channels Segments internal to the square that makes up the intersection should be
one-way when there is no opposing right turn channel.
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DTRF - Rules
Segments between Blocked Passages, where there is no access to the
segment should be closed to vehicular traffic.
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DTRF - Rules
Ferries: Same as for roads, except:
– Do not capture Validity Period
– Capture Pedestrian-only ferries as closed to all vehicular traffic
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DTRF - Rules
Combination Rules:1. Bus and Taxi lanes
– Capture as closed in both directions for all Vehicle Types except busses and/or taxies.
2. Capture DTRF of a road with Restricted Access as indicated by traffic signs.
3. Capture DTRF in such a way that no ‘restricted access islands’ exists.
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DTRF - Rules
Always close segments with the shown below to all vehicular traffic:
1. Passenger-Only Ferries
2. Walkways
3. Stepped Walkways
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Exercises
Given the situation in ‘reality’, which choice is correct? – Closed roads are indicated with opposing arrows on the segment
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Questions