Transcript KEY ASPECTS OF NAVIGATION - Freeway Intersections Freeway Intersection – Examples www.rmsi.com #2 Freeway Intersection  Before Starting an Intersection Check: – – – – – Non-Freeway Intersections Geometry FOWs FRCs Elevations  Make the corrections needed. www.rmsi.com #3 Freeway.

KEY ASPECTS OF NAVIGATION
- Freeway Intersections
1
Freeway Intersection – Examples
www.rmsi.com
#2
Freeway Intersection
 Before Starting an Intersection Check:
–
–
–
–
–
Non-Freeway Intersections
Geometry
FOWs
FRCs
Elevations
 Make the corrections needed.
www.rmsi.com
#3
Freeway Intersection – Definition
 Definition:
– Freeway intersection is the database representation of an access, exit,
and/or interchange of a freeway, motorway, or non-freeway.
www.rmsi.com
#4
Freeway Intersection – Classification
 Freeway Intersection is classified into three types:
– Motorway Interchange (MI)
– Motorway Exit/Access (ME)
– Other (OT)
www.rmsi.com
#5
Freeway Intersection – Motorway Interchange (MI)
 This type refers to an interchange between a motorway(FC-A
1)/freeway(FW 1) and another motorway(FC-A 1)/freeway(FW 1).
The interchange is considered to be one unit with the purpose of
changing motorways.
Freeway Intersection – Motorway Interchange (MI)
www.rmsi.com
#6
Freeway Intersection – Motorway Exit/Access (ME)
 This type refers to an interchange between a motorway(FC-A
1)/freeway(FW 1) and a non-motorway/freeway. Also, this type
refers to any place that a motorway/freeway begins/ends. The
interchange is considered to be one unit with the purpose of
entering/leaving the motorway/freeway.
Freeway Intersection – Motorway
Exit/Access (ME)
www.rmsi.com
#7
Freeway Intersection – Other (OT)
 This type refers to any ramped interchange between non-freeways
and other non-freeways. The interchange is considered one unit.
Freeway Intersection – Other (OT)
www.rmsi.com
#8
Freeway Intersection – Capturing Rules
 Freeway intersection will be captured for each:
–
–
–
–
–
Motorway interchange
Motorway exit/access
Freeway interchange
Freeway exit/access
Non-freeway exit/access with major slip roads
 The composing parts of a freeway intersection are:
– Road elements that represent slip roads.
– Road elements that represent parts of the connected motorways,
freeways, and/or non- freeways. This will include the road elements
between the exit(s) and entrance(s), and parts of the road element until
just beyond the connecting bridge/tunnel.
– Road elements with a Carriageway Designator that exist at the
interchange.
– Road elements that represent parallel roads at the interchange.
www.rmsi.com
#9
Freeway Intersection – Capturing Rules
 Freeway intersection will generally form one connected (not
necessarily closed) unit. In some cases the freeway intersection
can be composed of disconnected units because road elements
and junctions of each carriageway need to be part of the freeway
intersection.
 A freeway intersection should, in general, correspond with the car
driver’s perception of one construction.
www.rmsi.com
#10
Freeway Intersection – Capturing Rules
 Road elements and/or junctions that are composing parts of an
intersection can also be composing parts of a freeway intersection.
Once one composing part of an intersection is also a part of a
freeway intersection, all the road elements and/or junctions that
make up the intersection need to be part of the freeway
intersection.
 If a freeway intersection includes connections between two
motorways and connections between a motorway and nonmotorway, the freeway intersection type will be Motorway
Interchange (MI).
www.rmsi.com
#11
Freeway Intersection – Basic Cloverleaf Interchange

The freeway intersection is composed of all the major slip roads that
connect the two road elements as well as the road elements interior to the
major slip roads. All the orange segments are the composing parts of the
freeway intersection. The type is a motorway interchange (MI) because the
two streets are both motorways.
www.rmsi.com
#12
Freeway Intersection – Interchange where Slip Roads
are Offset

The freeway intersection is composed of all major slip roads and the
portion of motorway and non-motorway between the ramps. Since the
ramps are offset, the freeway intersection needs to continue on each
carriageway until it is parallel with the ramps. A node should have already
been placed along the carriageway and been part of the non-freeway point.
The type for this is motorway exit/access (ME).
www.rmsi.com
#13
Freeway Intersection – Requiring Extension across
Bridge/Tunnel

The freeway intersection is composed of slip roads and the portion of roads
between the ramps. The freeway intersection cannot begin/end at a
bridge/tunnel. In this example the freeway intersection needs to extend
one segment beyond the elevated street. This will carry type ME.
Simple example of when the
intersection needs to be extended
across a bridge/tunnel
Cannot begin or End On an
Elevation
www.rmsi.com
#14
Freeway Intersection – Carriageway Designator

At this interchange, HOV lanes exist that need to be incorporated into the
freeway intersection. The non-freeway points should only be placed on the
non-carriageway designator road elements. Type=ME.
Example of carriageway
designators at freeway
intersections
www.rmsi.com
#15
Freeway Intersection – Frontage Road

The freeway intersection includes the portion of frontage road that connect
the major slip roads to the dual carriageway. In this example, the FWI will
also need to extend just beyond the bridge/tunnel. Type=ME.
freeway intersection with
frontage roads and only one
set of major slip roads
The intersection needs to
be extended across a
bridge/tunnel
www.rmsi.com
#16
Freeway Intersection – Freeway begins at another
Freeway

In this situation the freeway intersection is composed of the slip roads that
connect the two freeways and the road elements that are between them.
The freeway intersection stops when the major slip roads transition into
the freeway. Type=MI.
www.rmsi.com
#17
Freeway Intersection – Freeway begins at another
Freeway

The freeway intersection is composed out of the slip roads and road
elements along the freeway between the slip roads. Type=MI.
www.rmsi.com
#18
Freeway Intersection – Start/End of a Motorway/Freeway

Freeway intersections will be captured at the beginning/ending of a
motorway/freeway. At the point where the motorway/freeway transitions
into a major slip road at a valence-2 node is not considered to be the
beginning/ending. The reason for this is because at that point the driver
cannot choose to enter/leave the motorway/freeway.
www.rmsi.com
#19
Freeway Intersection – Start/End of a Motorway/Freeway

The freeway intersection at the begin/end of the motorway/freeway is
composed of the road elements that make up the junction of the
motorway/freeway and the cross street.
Motorway
www.rmsi.com
#20
Freeway Intersection – At a Roundabout

If a motorway/freeway starts/ends without major slip roads at a roundabout,
the freeway intersection will be composed of the road elements that are
situated between the carriageways of the motorway/freeway along the
roundabout or the junction where the motorway/freeway joins the
roundabout. This will include any small slip roads that are present and
connect the motorway/freeway to the roundabout.
The freeway intersection
is composed of the
roundabout, the major
slip roads, and the
motorway between the
slip roads. Type=ME
www.rmsi.com
#21
Freeway Intersection – At a Roundabout

If only one major slip road joins the roundabout, the road elements
representing the roundabout will not be part of the freeway intersection
unless the roundabout is situated on top of, or below, the
motorway/freeway/non-freeway.
The freeway intersection is
composed of the road element
along the roundabout that is
between the two carriageways of
the motorway. This intersection
will carry the type ME.
Freeway intersection at the start/end of a motorway that occurs at a roundabout
www.rmsi.com
#22
Freeway Intersection – Overlapping Interchange
Complexes

Freeway intersections cannot overlap or be adjacent. Two or more
interchanges that overlap or are adjacent to each other shall be captured
as separate freeway intersections. Due to this rule, some road elements
(slip roads, parallel roads, motorways/freeways) will not be included in the
freeway intersection. At least one road element not associated with either
freeway intersection needs to be in-between to prevent the freeway
intersections from becoming adjacent
www.rmsi.com
#23
Freeway Intersection – Splitting of Intersections
 3000 Meters End to End
 Must be a gap between Intersections can not touch.
 Split on the Parallel portion of the intersection.
 Drivers perception of what is in the intersection.
www.rmsi.com
#24
Freeway Intersection – Splitting of Intersections

When determining how to separate the overlapping interchanges, the
correct composition of the Motorway Interchange (MI) is recommended
over the other freeway types. Also, it is preferred to separate the freeway
intersections along a parallel road rather than on the major slip road.
These are guidelines but due to the nature of some complex interchanges
it may not be possible to accommodate them.
Where interchanges overlap
Two interchanges overlap at the location noted.
Since a freeway intersection should correspond
with the driver’s perception of one construction,
the two cannot be combined into one large
intersection. Each will be its own freeway
intersection and a gap will exist between the
composing road elements of each.
www.rmsi.com
#25
Freeway Intersection – Splitting of Intersections

When the two separate freeway intersections are applied, make sure
there’s a gap between the two of them. Remember, freeway intersections
cannot be adjacent.
Freeway intersections
captured when they overlap
www.rmsi.com
#26
Freeway Intersection – Splitting of Intersections

This interchange has an intertwined group of slip roads that connect the
motorway to the FC-A 2 and the FC-A 4. This is a candidate to compose in
one large freeway intersection. The reason being is that a driver could
perceive this to be one construction and when the two interchanges are
combined, the freeway intersection is not larger than 3000m.
Freeway intersection captured
where two interchanges are
combined into one point
www.rmsi.com
The non-freeway intersections
are not displayed
#27
Freeway Intersection – Splitting of Intersections
Diagram showing how to separate
overlapping interchanges into
separate freeway intersections
A
C
B
www.rmsi.com
D
In this example, ramps and HOV
lanes connect 3 separate
interchanges. The extent of the
intersection is ~3000m in both
directions (A-B & C-D) so it’s too
large to be composed as one
freeway intersection. Since gaps
need to be present separating
freeway intersections, segments
will need to be split to
accommodate the need for a gap.
The splits will occur at the
extremities of each intersection.
#28
Freeway Intersection – Splitting of Intersections
Freeway intersections captured at
overlapping interchanges when
separate points need to be created
www.rmsi.com
#29
Freeway Intersection

It may be tempting to make one large freeway intersection and combine the
4 interchanges together. This wouldn’t be the preferred way to compose
the freeway intersection point. Remember, a freeway intersection should
correspond with the driver’s perception of one construction. This situation
involves 4 separate interchanges and the freeway intersections should
reflect that.
www.rmsi.com
#30
Freeway Intersection

This picture shows how freeway intersections would be captured into 4 separate
points. Each freeway intersection is composed of the slip roads at the interchange
and the motorways that exist between the slip roads.
www.rmsi.com
#31
Freeway Intersection – Roads Located Inside the
Interchange Complex

If a road is located inside the entire composed freeway intersection then it
must also be a composing part of that freeway intersection. This is true if
that road is at-grade with the road elements.
The composed freeway
intersection has road elements
that are entirely contained in the
point. The road elements meet
the cross street at grade and will
need to be a composing part of
the freeway intersection.
www.rmsi.com
#32
Freeway Intersection – Single Carriageways running
Parallel to a Motorway/Freeway

In some cases the major slip roads that are used to exit/access the
motorway/freeway and the cross streets overlap. In these cases, freeway
intersections will be captured for crossing roads from the highest road class
to the lowest road class.
FC-A 52

FC-A 51
Along this stretch of motorway the major slip roads that connect the
motorway to the cross streets overlap. The two major cross roads they
connect are an FC-A 51 and FC-A 52. Since the FC-A 51 is a higher class,
making the freeway intersection for that road element is done first.
www.rmsi.com
#33
Freeway Intersection – Single Carriageways running
Parallel to a Motorway/Freeway

The first step is to compose the freeway intersection out of the major slip roads that
connect the motorway to the FC-A 51, the portion of parallel road that facilitates this
connection, and the portion of motorway between the slip roads. By doing this the
road elements that make up this intersection point pass by two slip roads that are
used to access the FC-A 52. If a road element is bounded by a freeway intersection
that road element needs to be a composing part of that freeway intersection. It’s for
this reason that they are included in the freeway intersection even though they are
used to access the FC-A 51. The next step would be to create the freeway
intersection for the cross street that’s an FC-A 52.
www.rmsi.com
#34
Freeway Intersection – Single Carriageways running
Parallel to a Motorway/Freeway

The freeway intersection will be composed of the major slip road, parallel
road, and motorway. The point will be extended to include the portion of
motorway just across the bridge as well as the portion of cross street just
across the bridge. Once both of the intersection points have been added
there’s no major slip road that is not part of a freeway intersection so this
example is complete.
www.rmsi.com
#35
Freeway Intersection – Single Carriageways running
Parallel to a Motorway/Freeway

In some cases a cross street may not be part of the freeway intersection.
In the diagram below, freeway intersections have been created for the
highest road classes. Once that was done, no major slip road was left
without an associated freeway intersection. There’s no need to add any
other freeway intersections. This may look unusual but the major slip
roads that connect the motorway with the FC-A 51 are already part of
another freeway intersection and road elements can only be a composing
part of one freeway intersection.
FC-A 2
FC-A 51
FC-A 2
Schematic showing how to capture freeway intersections with overlapping
major slip roads and parallel roads
www.rmsi.com
#36
Freeway Intersection – Situations where no Freeway
Intersection will be captured

The following situations are not considered to be exit/access of a
motorway/freeway:
–
Crossing of a motorway/freeway with an entrance to or exit from a rest area
which has no other connection other than with the motorway/freeway
–
Transition of a DCW motorway/freeway into a SCW motorway/freeway without
a crossing with another road element
–
Connector only connecting the two carriageways of a motorway/freeway (cop
stop)
– Crossing of a motorway/freeway with a road only accessible by buses or taxis
which has no other connection than with the motorway/freeway
– Crossings representing splitting or converging lanes of a carriageway of a dual
carriage motorway/freeway
– Start/end of a carriageway designator
www.rmsi.com
#37
Freeway Intersection – Situations where no Freeway
Intersection will be captured

No freeway intersection will be added at this rest area. Non-freeway
intersection points are still required at every junction of the motorway and
the entrance/exits of the rest area.
Rest area where no freeway
intersection should be
captured
www.rmsi.com
#38
Freeway Intersection – Situations where no Freeway
Intersection will be captured

No freeway intersection will be added where the HOV lane starts/ends. A
non-freeway intersection point is still required at this junction.
Start/end of HOV lane that does
not require the addition of a
freeway intersection
www.rmsi.com
#39
Freeway Intersection – Extremities of Freeway Intersections

An intersection will be captured for all extremities of a freeway intersection.
These points will carry the type non-freeway (NF).
FW
FW
FW
FW
DC
W
Freeway extremity
intersections
Freeway intersection
MSR
FW
MSR
In the examples, some
of the intersection
points will already exist
because of the need to
have intersection points
when ramps depart
from the freeway. If a
point already exists at
the extremity of the
freeway intersection
point, do not add a
duplicate point.
Schematic showing freeway extremity intersections
www.rmsi.com
#40
Freeway Intersection – Intersections and FRC
 Functional Road Class (FRC) plays a major part in how MI, ME and
OT Intersections are differentiated between in the database. As
intersections are being worked, FRC values of ramps involved in
the composition of the intersections need to be verified for
correctness.
 When doing any work involving Level II attribution, it is within the
scope of edit to change/update any incorrect FRC values.
www.rmsi.com
#41
Freeway Intersection – Questions
www.rmsi.com
#42