geometric review and design (grad) 1 - ohio1 2| module 1 –design controls and exceptions odot...

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



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



Identify basic

information about a

facility known as design

designation

Functional Classification

Traffic Data

Terrain

Locale

Design Speed

Legal Speed

Design Controls



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



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



Design Controls



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




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




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



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



Design Controls



Traffic Data

From Certified Traffic Plates

Design Controls



Traffic Data


Key Data

Directional Distribution – for the Design Hour, not ADT

Design Controls



Traffic Data


Key Data


Design Speed – Design threshold

Design Controls



Traffic Data


Key Data



Legal Speed – Ohio Revised Code

Design Controls



Traffic Data


Key Data




NHS Project – controls some design criteria

Design Controls



Traffic Data


Key Data




NHS Project – controls some design criteria

Design Exceptions

Design Controls



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



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



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



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



Low-Speed Roadways (Sect 105.2)

1. Design Loading Structural Capacity

2. Lane Width

Only if required for the National

Network




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



Design Exception Process



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



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



Design Exceptions



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)



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)



Sect 106

Applicable Projects

ODOT Let Projects, except where noted on the next slide

Strongly encouraged on Local Let projects

DDSA



Non-Applicable Projects

Maintenance projects such as guardrail repair, mowing, striping, signing, RPMs, etc.

Pavement surface treatment projects

Spot repairs

Slot paving

DDSA



DDSA – Flow Charts for ALL Applicable Projects




PDP Paths 1 and 2

(No Alternative Analysis)




PDP Paths 1 and 2


PDP Paths 3, 4, and 5

(Alternative Analysis without

“Safety” in P&N AND not

requesting safety funds)




PDP Paths 1 and 2



(Alternative Analysis without

“Safety” in P&N AND not



(Alternative Analysis with

“Safety” in P&N AND/OR




DDSA – Minimal Safety Assessment




Obtain applicable studies for

project area (including safety

studies)






studies)

Determine if location is on ODOT

SIP Map






studies)


SIP Map

Determine ranking on ODOT or

local safety priority list or within a

Local Road Safety Plan (LRSP)






studies)


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



Key Terms

Functional Classification

Traffic Data

Terrain

Locale

Design Speed

Legal Speed

Design Exception


Data-Driven Safety Analysis

Module Review

geometric review and design (grad) 1 - ohio1 2| module 1 –design controls and exceptions odot...

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