User:Hawkeygoal/IL Pages/IL OSE (2016 07) View history

Latest revision as of 02:27, 26 February 2017

Overview

The goal of this page update is add additional guidance on the handling of elevation relative to overpasses in Illinois by revising the Major roads section of the Illinois wiki.

This new page is currently undergoing modifications. The information presented should be considered a draft, not yet ready for use. Content is being prepared by one or more users. Do not make any changes before you send a private message to this user.

This guidance attempts to address elevation items of concern within the state. The proposed Illinois guidance:

addresses multi-level subterranean roads present in the City of Chicago,
aligns minimum segment length with that of speed limits (for same reasons), and
attempts to address culverts that may contribute to substantial detours, particularly in rural areas.

In this, we hope to provide clarity in guidance for unique circumstances within the state and minimize the introduction of additional junctions to the map in addressing elevation concerns.

Content

This content is under development for the Illinois wiki. This page should not be considered official guidance. Please refer to Illinois for official state guidance.

True Elevation

In Illinois, an expanded implementation of the general guidance for elevation and overpasses, underpasses, and bridges, has been adopted. Please refer to the these sections for additional guidance.

True Elevation refers to layers of road decks supported above and below the terrain (ground) with open space between them. In essence, any road segment which a bird, such as a hawk, could fly underneath should be elevated above ground level. The inverse condition applies to tunnels or multi-level underground segments where your average groundhog could tunnel between them.

What is an overpass? An overpass is a general term for any road, walkway, railroad, bridge, or other mapped structure crossing over an impediment such as a waterway, natural formation, or another road, walkway, railroad, or bridge. In our mapping context it can also be conceptualized underground where tunnels crossing over, or under, one another.

Elevation

Apply these points to the use of true elevation:

All roads when not supported above or tunneled below the terrain are set to ground elevation unless otherwise noted.
If a road segment is supported above the terrain or another road segment, the elevation of the segment should be set one higher (+1) than the segment or terrain (ground) immediately beneath.
The elevation of road segments completely or transitionally sub-surface should be negative and one less than (-1) the surface, tunnel, or level immediately above.
Ramps are to be set to the lower elevation of the roadways to which they junction unless passing over or under other segments.

Segmentation

When creating segments to implement this guidance, please observe these precepts:

Create junction nodes for elevation purposes at the point the physical change in elevation occurs unless otherwise specified.
Do not cut a segment within 200 feet (60m) of an existing junction.
Do not create a segment less than 200 feet (60m) in length.
Underground segments should be cut at least 50 feet (15m) before, or after, the entrance to the subterranean section.
Check the tunnel option for any underground segment.

Culverts

A culvert is a tunnel allowing a stream or open drain to pass under a roadway. Under normal circumstances these are not to be mapped. However, an elevated segment for a culvert may be created to support real-time closures (due to significant flooding or repair) when all these conditions are met:

The culvert of significant construction requiring multiple day closures to repair.
The culvert not located near the center of the segment.
The segment is heavily populated by potential destinations and a route to the wrong end of the segment would result in a un-routed detour of more than one mile.

Discussion

This proposal is still being discussed and drafted by Illinois State and Area Managers.

@@ Line 2: / Line 2: @@
 ''The goal of this page update is add additional guidance on the handling of elevation relative to overpasses in Illinois by revising the [[Illinois#Major orads|Major roads]] section of the Illinois wiki.''
-{| class="wikitable" style="width:100%; text-align:center; color:red; font-weight:bold"
+{{Construction|revision=no|section=no|draft=yes|contact=http://www.waze.com/forum/ucp.php?i=pm&mode=compose&subject=A%20Wiki%20Question&username=Hawkeygoal|contacttype=hawkeygoal|open=no}}
-|-
-| This information is under consideration for the Illinois state wiki.<br>It should not be considered official guidance.
-|}
+This guidance attempts to address elevation items of concern within the state. The proposed Illinois guidance:
+* addresses multi-level subterranean roads present in the City of Chicago,
+* aligns minimum segment length with that of speed limits (for same reasons), and
+* attempts to address culverts that may contribute to substantial detours, particularly in rural areas.
+In this, we hope to provide clarity in guidance for unique circumstances within the state and minimize the introduction of additional junctions to the map in addressing elevation concerns.
 <!--
 The current wiki guidance on this topic can be found in [[Illinois#Major_roads|this section]].
@@ Line 13: / Line 16: @@
 == Content ==
-=== Overpass Segmentation and Elevation ===
+{{mbox|type=construction|textstyle=color:red;|text=This content is under development for the Illinois wiki. This page should not be considered official guidance. Please refer to [[Illinois]] for official state guidance. }}
+=== True Elevation ===
 In Illinois, an expanded implementation of the general guidance for [[Creating_and_editing_road_segments#Road_elevation|elevation]] and [[Overpasses,_Underpasses_and_Bridges|overpasses, underpasses, and bridges]], has been adopted. Please refer to the these sections for additional guidance.
-In essence, the concept is that any road segment which a bird, such as a hawk, could fly underneath should be elevated above ground level. The inverse condition applies to tunnels or multi-level underground segments where they would be elevated below the ground level.
+''True Elevation'' refers to layers of road decks supported above and below the terrain (ground) with open space between them. In essence, any road segment which a bird, such as a hawk, could fly underneath should be elevated above ground level. The inverse condition applies to tunnels or multi-level underground segments where your average groundhog could tunnel between them.
-'''What is an overpass?'''
+''What is an overpass?'' An overpass is a general term for any road, walkway, railroad, bridge, or other mapped structure crossing over an impediment such as a waterway, natural formation, or another road, walkway, railroad, or bridge. In our mapping context it can also be conceptualized underground where tunnels crossing over, or under, one another.
-An overpass is a general term for any road, walkway, railroad, bridge, or other mapped structure crossing over an impediment such as a waterway, natural formation, or another road, walkway, railroad, or bridge.
-'''Elevation'''<br />
+===== Elevation =====
-These elevation rules apply:
+Apply these points to the use of true elevation:
-:* All surface roads when not supported above or tunneled below the ground are set to ground elevation unless otherwise described in this section.
+:* All roads when not supported above or tunneled below the terrain are set to ground elevation unless otherwise noted.
-:* If a road segment is supported above the terrain or another road segment, the elevation of the segment should be set one higher (+1) than the segment or terrain immediately underneath.
+:* If a road segment is supported above the terrain or another road segment, the elevation of the segment should be set one higher (+1) than the segment or terrain (ground) immediately beneath.
 :* The elevation of road segments completely or transitionally sub-surface should be negative and one less than (-1) the surface, tunnel, or level immediately above.
-:* Ramps should be set to the lower elevation of the roadways to which it junctions unless they themselves pass over or under other segments as described above.
+:* Ramps are to be set to the lower elevation of the roadways to which they junction unless passing over or under other segments.
-:* '''''Please contact a [[Illinois#Area_Managers|State Manager]] before making elevation changes on freeways or interchanges (including connecting ramps and segments).'''''
-'''Segmentation'''<br />
+===== Segmentation =====
 When creating segments to implement this guidance, please observe these precepts:
-:* Create junction nodes for elevation purposes at the point the physical change in elevation occurs unless otherwise guided in this section.
+:* Create junction nodes for elevation purposes at the point the physical change in elevation occurs unless otherwise specified.
-:* Use existing junction nodes when within 500 feet of an elevation change. ''For example, do not create new junction nodes for elevation purposes at an interchange when ramps junction with the main road within 500 of the physical overpass.''
+<!--
-:* Do not create an elevated overpass less than 75 feet in length.
+:* Use existing junction nodes when within 500 feet of an elevation change. ''For example, do not create new junction nodes for elevation purposes at an interchange when ramps junction with the main road within 500 feet of the physical overpass.''
-:* '''''Contact an [[Illinois#Area_Managers|SM or LAM]] for approval to create overpasses, or single junction nodes for elements less than 75 feet in length (overpasses, culverts, etc.).'''''
+:* Do not create an elevated overpass less than 150 feet in length (with a strong preference for 200 feet).
+-->
+:* Do not cut a segment within 200 feet (60m) of an existing junction.
+:* Do not create a segment less than 200 feet (60m) in length.
+:* Underground segments should be cut at least 50 feet (15m) before, or after, the entrance to the subterranean section.
+:* Check the tunnel option for any underground segment.
+===== Culverts =====
+A ''culvert'' is a tunnel allowing a stream or open drain to pass under a roadway. Under normal circumstances these are not to be mapped. However, an elevated segment for a culvert may be created to support real-time closures (due to significant flooding or repair) when '''all''' these conditions are met:
+:* The culvert of significant construction requiring multiple day closures to repair.
+:* The culvert not located near the center of the segment.
+:* The segment is heavily populated by potential destinations and a route to the wrong end of the segment would result in a un-routed detour of more than one mile.
 == Discussion ==
+This proposal is still being discussed and drafted by Illinois State and Area Managers.
+<!--
 This proposal is still being drafted prior to open discussion.
-<!--
+--
 This proposal is under discussion on the forums, at the following link: https://www.waze.com/forum/viewtopic.php?f=253&t=181690&p=1419007#p1419007
 -->

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