TRENDS AND HIGHWAY CLASSIFICATIONS

Spring 2015

Examples of highway design problems

http://www.weathergraphics.com/tim/dumbroad/justkid.jpg

Examples of highway design problems

http://www.righthandfirm.com/photos/highway-design.jpg

Examples of highway design problems

http://weathergraphics.com

Examples of highway design problems

Examples of highway design problems

Important Issues in Highway Design

• Automobile Oriented Society– More cars than drivers (BTS Survey 03)

• Shift from construction of new facilities to maintenance of existing facilities (e.g., lane widening, paving, intelligent transportation systems, etc.)

• Resurgence in highway funding– Concern for conditions of infrastructure– Renewed public willingness for public

expenditures (e.g., current bill in Texas to increase funding for highways)

– Reauthorization of transportation funds ($286.5B)

I-35W Bridge Collapse

Important Issues in Highway Design

• Fleet of vehicles– Larger trucks/smaller vehicles– Better vehicles performance and

design (e.g., lower center of gravity, improved acceleration, lighter vehicle components, etc.)

• Age of population– Baby boomers are getting older (20%

65+ in 2003)– Safety issues with older (i.e., visual

search, reaction time, more fragile health, etc.)

Important Issues in Highway Design

• Value Engineering– New area that aims to find ways to save

money in design– Has been applied in highway design– Can compromise safety (e.g., Highway 407

in Ontario, Canada)• Liability

– Increasing number of lawsuits (DOTs, Cities, MPOs, etc.)

– Usually always based on (un)safety (after crashes occur)

Important Issues in Design

• Safety Audits– Becoming increasingly popular (liability is a factor)– Explicitly look at all safety components of a project (from

initial concept to construction)– Goes beyond design guidelines

• New design criteria under development– Less focused on vehicle speed– Sensitive context design

• Transportation Security– Terrorist threats against transportation infrastructures– See, e.g.,

http://onlinepubs.trb.org/Onlinepubs/dva/SecurityActivities.pdf

The Design Objective

• A well-designed road will provide the intended level of service, at an acceptable cost, with an acceptable level of safety. It will also reflect local values and policy, which will vary from location to location. If it has been designed with care and sound judgment, it will place appropriate importance on safety, cost, service, environmental values, and appearance.

Goals of Highway Design

• Traffic Quality• Economy• Aesthetics• Function (to be discussed later)• Traffic Safety• Environmental protection

Road Network Design

• The road network is part of the overall traffic infrastructure (railway, waterway, communication, etc.).

• It is the essential element in developing rural and urban areas.

• Consequently, the road network design influences the spatial development as well as the local space structure.

• The task of network design should be to arrange and design the individual road sections according to their respective functions within the scope of transportation and regional planning

Role of Highways• Two primary roles of Highway and Street

Networks are: • Travel Mobility: To provide users with means

to travel from a point of origin to a point of destination the most efficient and safest way possible

• Access: To provide users access to services and property the most efficient way possible

Mobility

Access

Wright and Dixon (2004) Figure 1-2

Functional Classification

• Based on Design Typeseg. Freeways, Conventional Streets and highways

• Based on route numbering eg. U.S., State, County• Based on Administrative System eg. National and Non-National Highways• Functional Classification

Urban/Rural Areas• Urban and rural differ with regard to

– Density – types of land use– density of streets and highway networks– natures of travel patterns

• Urban Areas: places within boundaries set by responsible State and local officials having a population above 5,000 people– Urbanized (>=50,000) Small urban (5,000-50,000)

• Rural Areas: everything else

Rural Functional System

• Rural Principal Arterial (Interstate)• Rural Minor Arterial (Intercity,

Intertowns)• Rural Collector System (Intracounty)

– Major Collectors • Counties and towns not served by higher

systems– Minor Collectors

• Accumulate traffic from local roads

• Rural Local Road System– Access to land adjacent to collectors

Rural Highways

Systems Percentage

Principal arterials

2-4%

Principal + Minor Arterials

7-10%

Collectors 20-25%

Local roads 60-75%

Urban Functional System

• Urban Principal Arterial• Urban Minor Arterial Street• Urban Collector Streets• Urban Local Road System

Urban Highways

Systems PercentageTraffic Volume

PercentageLength

Principal arterials 40-65% 5-10%

Principal + Minor Arterials

65-80% 15-25%

Collectors 5-10% 5-10%

Local roads 10-30% 60-80%

Wright and Dixon (2004) Figure 1-3

Wright and Dixon (2004) Table 1-1

Wright and Dixon (2004) Table 1-2

The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) was enacted August 10, 2005, as Public Law 109-59. TEA-21 authorizes the Federal surface transportation programs for highways, highway safety, and transit for the 5-year period 2005-2009.

More Info: http://www.fhwa.dot.gov/reauthorization/

Reauthorization of TEA-21

The Moving Ahead for Progress in the 21st Century Act or the ‘MAP-21’ was passed by the Senate in March 2012 and the House on June 29th, 2012. President signed it on July 6th, 2012. Total budget: $105.2 billion (27 months).

More info:

http://www.ncsl.org/documents/transportation/TRN-JulyAug2012.pdf

http://www.fas.org/sgp/crs/misc/R40431.pdf