CE 806.1 Introduction

8/3/2019 CE 806.1 Introduction

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GEOMETRIC DESIGN OFGEOMETRIC DESIGN OF

HIGHWAYS/FREEWAYSHIGHWAYS/FREEWAYS(CE(CE -- 806)806)

OVERVIEW OF THE HIGHWAYPLANNING

Spring 2012

Dr. Muhammad Babar Khan

National Institute of Transportation (NIT)

School of Civil & Environmental Engineering (SCEE)

National University of Sciences & Technology (NUST)2


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OVERVIEW OF THE HIGHWAYOVERVIEW OF THE HIGHWAY

PLANNINGPLANNING

y Highway design is only one element in theoverall highway development process.

y It is during the first three stages:

planning project development

design

yDesigners and communities, working

together, can have the greatest impacton the final design features of theproject.

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THE STAGES OF HIGHWAYTHE STAGES OF HIGHWAY

DEVELOPMENTDEVELOPMENT

y The five basic stages in the highway:

Planning

Project development (preliminary design)

Final design

Right of way

Construction

y

Although these activities are distinct, there isconsiderable overlap between all phases of

highway planning and development.

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THE STAGES OF HIGHWAYDEVELOPMENTTHE STAGES OF HIGHWAYDEVELOPMENT

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PlanningPlanning

y The initial definition of the need for any highway

or bridge improvement project takes place

during the planning stage.

y It occurs at the State, regional, or local level,depending on the scale of the proposed

improvement.

y This is the key time to get the public involved

and provide input into the decision makingprocess.

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PlanningPlanning

y The problems identified usually fall into one or

more of the following four categories:

1.The existing physical structure needs major

repair/replacement (structure repair).2.Existing or projected future travel demands exceed

available capacity, and access to transportation and

mobility need to be increased (capacity).

3.The route is experiencing an inordinate number of

safety and accident problems that can only be

resolved through physical, geometric changes (safety).

4.Developmental pressures along the route make a

reexamination of the number, location, and physical

design of access points necessary (access). 7


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PlanningPlanning

y It is important that all parties agree that the

problem exists, pinpoint what the problem is,

and decide whether or not they want it fixed.

y For example, some communities do not want toimprove the roadway for fear that such action

will encourage more growth along the corridor.

y Road access may be a problem, but a

community may decide it is better not toincrease access.

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y If a consensus cannot be reached on the

definition of the problem at the beginning, it will

be difficult to move ahead in the process and

expect consensus on the final design.

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Planning Government LevelsPlanning Government Levels

y State Planning.

State DOTS are required to develop and

maintain a statewide, multimodal

transportation planning process. 20year projections of traffic demands.

Every few years, the State selects

improvement projects based on the long

range plan and includes them in the Statewide

Transportation Improvement Program, or

STIP.

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y Regional Planning.

Metropolitan planning organizations (MPOs)

develop their own regional plans, which must

rely on the State planning process. The plan not only defines a region's

multimodal transportation needs, but also

identifies the local funding sources that will be

needed to implement the identified projects.

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y Local Planning.

Most cities and counties follow a similar

process of project identification, conceptual

costing, and prioritization of the roadways forwhich they are responsible.

These are roads that are not the

responsibility of the State DOT.

The State must work with localities to get

their input into the long range plan and

Statewide Transportation Improvement

Program (STIP)12


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Factors To Consider DuringFactors To Consider During

PlanningPlanning

y During planning, key decisions are made that

will affect and limit the design options in

subsequent phases.

y Some questions to be asked at the planningstage include:

How will the proposed transportation improvement

affect the general physical character of the area

surrounding the project? Does the area to be affected have unique historic or

scenic characteristics?

What are the safety, capacity, and cost concerns of

the community? 13


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Factors to consider in PlanningFactors to consider in Planning

y Answers for such questions are found in

planning level analysis, as well as in public

involvement during planning

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Project DevelopmentProject Development

y At this stage, the environmental analysis

intensifies.

y The level of environmental review varies widely,

depending on the scale and impact of theproject.

y It can be a comprehensive document that

analyzes the potential impact of proposed

alternatives.

y Or a modest environmental review completed

in a matter of weeks.

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y The basic steps in this stage include the

following:

Refinement of purpose and need

Development of a range of alternatives (including the"nobuild" and traffic management system [TMS]

options)

Evaluation of alternatives and their impact on the

natural and built environments

Development of appropriate mitigation

y Project development level helps to define major

features of project through the remainder of

the design and construction process. 16


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Scoping brings all participants into theScoping brings all participants into the

process.process.

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y Scoping

many decisions made during the scoping

phase of project development

It is important that the various stakeholdersin the project be identified and provided with

the opportunity to get involved.

y Assessing the Character of an Area

physical location carefully during this stage of

project planning.

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The physical character of an area can vary,The physical character of an area can vary,

from a peaceful countryside...from a peaceful countryside...

. . . to an urban corridor.

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Character of an AreaCharacter of an Area

y Some of the questions to ask at this stage

include: What are the physical characteristics of the corridor? Is it in an

urban, suburban, or rural setting?

How is the corridor being used (other than for vehicular traffic)?

Are there destination spots along the traveled way that require

safe access for pedestrians to cross? Do bicycles and other

nonmotorized vehicles or pedestrians travel along the road?

What is the vegetation along the corridor? Is it sparse or dense;

are there many trees or special plants?

Are there important viewsheds from the road?

What is the size of the existing roadway and how does it fit into

its surroundings?

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y Are there historic or especially sensitive environmental features

(such as wetlands or endangered species habitats) along the

roadway?

y How does the road compare to other roads in the area?

y Are there particular features or characteristics of the area that thecommunity wants to preserve (e.g., a rural character, a

neighborhood atmosphere, or a main street) or change (e.g., busy

electrical wires)?

y Is there more than one community or social group in the area?Are

different groups interested in different features/characteristics?Are

different groups affected differently by possible solutions?

y Are there concentrations of children, the elderly, or disabled

individuals with special design and access needs (e.g.,pedestrian

crosswalks, curb cuts, audible traffic signals, median refuge areas)?

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Final DesignFinal Design

y The product of this stage is a complete set of

plans, specifications, and estimates (PS&Es) of

required quantities of materials ready for the

solicitation of construction bids and subsequentconstruction.

y The following are some important

considerations of design, including:

Developing a concept Considering scale

Detailing the design.

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y Developing a Concept

A design concept gives the project a focus and

helps to move it toward a specific direction.

All elements of highway design

need to be part of an overall

concept.

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y A multidisciplinary design team consists of some of

these professionals.

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y For this overpass, an artist and structural engineers

worked together to achieve a design that represents

the unique characteristics of the area

(Thomas Road Overpass, Phoenix, AZ) 25


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y Piers were designed and decorated with art forms

from the Hohokam tribe, whose ancient burial

ground is near the overpass.

(Thomas Road Overpass, Phoenix, AZ) 26


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y Considering Scale

People driving in a car see the world at a

much different scale than people walking on

the street. For example, it has become common in many

suburban commercial areas that a shopper

must get in the car and drive from one store

to the next.

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y Main streets are much more pedestrian friendly,

partly because of their design scale, than the typical

modern commercial strip

A typical "modern" commercial strip. 28


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A "main street. (Bellevue Avenue, Newport, RI)

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y Considering Scale

The design element with the greatest effect

on the scale of the roadway is its width, or

cross section. The cross section can include a clear zone,

shoulder, parking lanes, travel lanes, and/or

median.

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y Elements (or a lack of elements) along the

roadside also contribute to the perceived width

of the road and can even affect the speed at

which motorists travel.

Relatively minor differences in

roadway cross section and the

treatment of the roadway edge can

have major effects on perceived width 31


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y Detailing the Design

Particularly during the final design phase, it is

the details associated with the project that

are important. Often it is the details of the project that are

most recognizable to the public.

A special type of tree that was used as part of

the landscape plan, antique lighting, bricksidewalks, and ornamental traffic barriers are

all elements of a roadway that are easily

recognizable and leave an impression.32


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y A multidisciplinary design team can produce an aesthetic

and functional product when the members work together

and are flexible in applying guidelines. (BaltimoreWashington

Parkway,MD)

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y An innovative barrier design was used on the Baltimore

Washington Parkway.(MD)

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Right of way, Construction, andRight of way, Construction, and

MaintenanceMaintenancey Right of way is purchased, construction bid

packages are made available, a contractor is

selected, and construction is initiated.

y

During the rightofway acquisition andconstruction stages, minor adjustments in the

design may be necessary.

y There should be continuous involvement of the

design team throughout these stages.y Once construction has been completed, the

facility is ready to begin its normal sequence of

operations and maintenance.35


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Elements of a Successful ProcessElements of a Successful Process

y In other words, a successful highway design process

includes the following:

y Early and continuous public involvement throughout the

project

y The use of visualization techniques to aid the public

y Early and continuous use of a multidisciplinary design

team

y The application of flexible and creative design criteria

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y Visualization tools were used to generate these images showing the

public a proposed highway improvement. (State Highway 38,MN)

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Source:Source:y US Department ofTransportation (DOT): Federal

HighwayAdministration (FHWA) website.

y http://www.fhwa.dot.gov/

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CE 806.1 Introduction

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