Transcript DTRF_v1.0

KEY ASPECTS OF NAVIGATION Direction of Traffic Flow (DTRF)
1
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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#2
Description
Direction of Traffic Flow Indicators
– Traffic signs
• “One Way”
• “Do not enter”
– Painted arrows on road
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#3
Description
Traffic signs may have:
– Vehicle Type Restriction
– Time Related Info
Except Busses
Direction of Traffic Flow
‘closed’ to all vehicles
except busses
6:30 to 9:00 AM
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Direction of Traffic Flow
‘closed’ from 06:30 to 09:00
#4
Description
 Consider both:
– Legal meaning of sign
– Exact location of the sign
 Roads under construction:
– DTRF for when construction is complete
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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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.
#5
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.
A
Add a node at the location of the
sign to break the segment
Apply DTRF to the appropriate segment
B
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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
one-ways
Dead-end with
one-ways
Impossible to
depart from node
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Impossible to
reach node
DTRF - Rules
Traffic Circles (FOW 4)

Must be one-way at all times
Clockwise & oneway
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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.
– Impossible to reach
the node
– Not allowed in data
Infinite source
Impossible to reach
(hidden) node
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DTRF - Rules
Infinite Sink

All segments meeting at a node are one-way toward the node.
– Impossible to depart
the node
– Not allowed in data
Infinite
sink
Impossible to
depart from
(hidden) node
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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
clockwise flow
at the node
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One-ways have
counterclockwise
flow at the node
DTRF - Rules
Capture minor roads:
Driveway
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.
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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
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