Geometric Review and Design (GRAD) 1 - Ohio1 2| Module 1 –Design Controls and Exceptions ODOT L&D...
Transcript of Geometric Review and Design (GRAD) 1 - Ohio1 2| Module 1 –Design Controls and Exceptions ODOT L&D...
Geometric Review and Design (GRAD)
Design Controls
and Exceptions
1
12 | Module 1 – Design Controls and Exceptions
ODOT L&D Vol. 1 – Section 100
Introduce what is
needed in Geometric
Design
Understand the key
design controls and
how they impact
Geometric Design
Understand the Design
Exception process
Learning Objectives
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ODOT L&D Vol. 1 – Section 100
ODOT Location and Design
(L&D) Manuals
Volume 1 – Roadway Design
Volume 2 – Drainage Design
Volume 3 – Highway Plans
This course will focus on the
L&D Volume 1 and minimally
on L&D Volume 3
The Manual
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Identify basic
information about a
facility known as design
designation
Functional Classification
Traffic Data
Terrain
Locale
Design Speed
Legal Speed
Design Controls
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Functional Classification (Sect 101)
The systematic grouping of highways by the character of service they provide
Standards and level of service vary according to the function of the highway facility
Rural - Areas outside the boundaries of urban
areas
Urban – Places with population of 5,000 or
more
Incorporated as cities, villages or towns
Other territory included in urbanized areas
Design Controls
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Functional Classification (Sect 101)
The systematic grouping of highways by the character of service they provide
Standards and level of service vary according to the function of the highway facility
Rural - Areas outside the boundaries of urban
areas
Urban – Places with population of 5,000 or
more
Incorporated as cities, villages or towns
Other territory included in urbanized areas
Design Controls
Use TIMS to find Functional Classifications
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Design Controls
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Roadway Classifications
National Network (or National Truck Network); Sect 105.3
Established in 1982; includes the
Interstate Routes and FAP Routes
A single 12-foot wide lane must be
provided in each direction; Design
Exception required when not provided
no matter whether high-speed or low-
speed facility.
TIMS will identify FAP and National
Truck Network routes
Design Controls
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Roadway Classifications
Strategic Highway Network (STRAHNET)
62,791-mile system (nationwide) of
roads deemed necessary for
emergency mobilization and
peacetime movement to support U.S.
military operations.
Requires minimum 16-foot vertical
clearance along these routes;
coordination must be completed
with SDDCTEA
Design Controls
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Roadway Classifications
National Highway System (NHS)
Federal-Aid Highway System
Consists of the most important
routes for commerce and trade in
the United States
Includes the Interstate System,
STRAHNET, and critical intermodal
connectors to passenger/freight
facilities
Design Controls
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Traffic Data (Sect 102)
Foundation upon which
designs are based
Important that adequate
traffic data be available early
in the development of the
project’s design
Important that this data be
coordinated with various
geometric regions of the State
to avoid inconsistencies
Design Controls
ADT Classes
Passenger Cars
Commercial A: RVs, school
buses
Commercial B: tractors, semis
Commercial C: dual-tired
trucks
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Design Controls
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Traffic Data
From Certified Traffic Plates
Design Controls
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Traffic Data
From Certified Traffic Plates
Key Data
Directional Distribution – for the Design Hour, not ADT
Design Controls
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Traffic Data
From Certified Traffic Plates
Key Data
Directional Distribution – for the Design Hour, not ADT
Design Speed – Design threshold
Design Controls
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Traffic Data
From Certified Traffic Plates
Key Data
Directional Distribution – for the Design Hour, not ADT
Design Speed – Design threshold
Legal Speed – Ohio Revised Code
Design Controls
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Traffic Data
From Certified Traffic Plates
Key Data
Directional Distribution – for the Design Hour, not ADT
Design Speed – Design threshold
Legal Speed – Ohio Revised Code
NHS Project – controls some design criteria
Design Controls
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Traffic Data
From Certified Traffic Plates
Key Data
Directional Distribution – for the Design Hour, not ADT
Design Speed – Design threshold
Legal Speed – Ohio Revised Code
NHS Project – controls some design criteria
Design Exceptions
Design Controls
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Terrain and Locale (Sect 103)
3 types of terrain
Level – grades no more than 2%
Rolling – causes heavy vehicles to
reduce speeds, but not to a crawl
speed
Hilly – heavy vehicles operate at
crawl speeds
Locale is used to describe the
type of area and generally
refers to the character and
extent of development in the
vicinity
Design Controls
Heavy vehicles – vehicle with
mass/power ratio of 200 lb/hp;
typically a semi-truck
Crawl speed – maximum sustained
speed that a heavy vehicle can
maintain on an extended upgrade
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Design Speed & Legal Speed (Sect
104)
Design Speed – selected speed used to determine the various geometric design features of the roadway.
Legal Speed * – the legislated authorized maximum speed limit of a section of roadway
Design Speed must equal Legal Speed or Legal Speed + 5mph
Design ControlsLow-
Speed: less than 50 mph
High-
Speed:
50 mph and faster
* Identified in Ohio Revised Code
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Sect 105
Controlling Criteria - minimum
values or ranges of design criteria
Where it is not practical to meet
one of the Controlling Criteria due
to various impacts or costs, a Design
Exception is a formal approval
process to evaluate and document
the decisions.
Design Exceptions
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High-Speed Roadways (Sect 105.2)
1. Lane Width
2. Shoulder Width
3. Horizontal Curve Radius
4. Maximum Grade
5. Stopping Sight Distance (Horizontal
and crest vertical curves)
6. Superelevation Rate
7. Vertical Clearance
8. Pavement Cross Slope
9. Design Loading Structural Capacity
Controlling Criteria
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Low-Speed Roadways (Sect 105.2)
1. Design Loading Structural Capacity
2. Lane Width
Only if required for the National
Network
Controlling Criteria
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Criteria that can be “flexible”
1. Intersection Sight Distance
Get Stopping Sight Distance
2. Superelevation Rate
3. Lane Width
4. Shoulder Width
Use HSM to quantify impacts
Understand the context of
the design
Common Flexible Design Criteria
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Design Exception Process
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DE Processing
By the District using electronic
submission process found on ORE
website
DE Approvals
LPA projects will be approved by the
District Capital Programs
Administrator
Non-local projects will be approved by
Administrator of ORE; ORE will
coordinate with FHWA as appropriate
Design Exception Approvals
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DE document must contain:
1. Design Designation of the project
2. Title sheet location map (Design
Exception Document Map)
3. Controlling Criteria affected by
the proposed design exception
4. Description of the project
5. Proposed mitigation (if any)
6. Support for the proposed
deviation
7. GCAT/CAM Safety Analysis Output
Design Exception Documentation
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Design Exceptions
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Design Exceptions
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The HSM provides methods of quantifying safety
performance for a project and each of the
alternatives similar to the way we quantify traffic
operations, construction costs, and environmental and
property impacts
Data-Driven Safety Analysis (DDSA)
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Can also be used to determine if there is a history of crashes within the project that can be “reasonably and practically” addressed through the inclusion of countermeasures in the project
Factors that can affect countermeasures being “reasonable and practical” include but not limited to
Cost
Environmental or R/W impacts
Being compatible with project
Schedule impacts
Data-Driven Safety Analysis (DDSA)
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Sect 106
Applicable Projects
ODOT Let Projects, except where noted on the next slide
Strongly encouraged on Local Let projects
DDSA
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Non-Applicable Projects
Maintenance projects such as guardrail repair, mowing, striping, signing, RPMs, etc.
Pavement surface treatment projects
Spot repairs
Slot paving
DDSA
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DDSA – Flow Charts for ALL Applicable Projects
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DDSA – Flow Charts for ALL Applicable Projects
PDP Paths 1 and 2
(No Alternative Analysis)
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DDSA – Flow Charts for ALL Applicable Projects
PDP Paths 1 and 2
(No Alternative Analysis)
PDP Paths 3, 4, and 5
(Alternative Analysis without
“Safety” in P&N AND not
requesting safety funds)
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DDSA – Flow Charts for ALL Applicable Projects
PDP Paths 1 and 2
(No Alternative Analysis)
PDP Paths 3, 4, and 5
(Alternative Analysis without
“Safety” in P&N AND not
requesting safety funds)
PDP Paths 3, 4, and 5
(Alternative Analysis with
“Safety” in P&N AND/OR
requesting safety funds)
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DDSA – Minimal Safety Assessment
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DDSA – Minimal Safety Assessment
Obtain applicable studies for
project area (including safety
studies)
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DDSA – Minimal Safety Assessment
Obtain applicable studies for
project area (including safety
studies)
Determine if location is on ODOT
SIP Map
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DDSA – Minimal Safety Assessment
Obtain applicable studies for
project area (including safety
studies)
Determine if location is on ODOT
SIP Map
Determine ranking on ODOT or
local safety priority list or within a
Local Road Safety Plan (LRSP)
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DDSA – Minimal Safety Assessment
Obtain applicable studies for
project area (including safety
studies)
Determine if location is on ODOT
SIP Map
Determine ranking on ODOT or
local safety priority list or within a
Local Road Safety Plan (LRSP)
Analyze Historical/Observed Crash
Data
Reference: Office of Program Management
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Key Terms
Functional Classification
Traffic Data
Terrain
Locale
Design Speed
Legal Speed
Design Exception
Controlling Criteria
Data-Driven Safety Analysis
Module Review