Transcript HIGHWAY FUNCTIONS: Systems and Classifications

TRENDS AND HIGHWAY
CLASSIFICATIONS
Spring 2015
Examples of highway design problems
http://www.weathergraphics.com/tim/dumbroad/justkid.jpg
Examples of highway design problems
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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
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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 Types
eg. 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
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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
Collectors
7-10%
20-25%
Local roads
60-75%
Urban Functional System
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Urban
Urban
Urban
Urban
Principal Arterial
Minor Arterial Street
Collector Streets
Local Road System
Urban Highways
Systems
Percentage
Traffic Volume
Percentage
Length
Principal arterials
40-65%
5-10%
Principal + Minor
Arterials
65-80%
15-25%
5-10%
5-10%
10-30%
60-80%
Collectors
Local roads
Wright and Dixon (2004) Figure 1-3
Wright and Dixon (2004) Table 1-1
Wright and Dixon (2004) Table 1-2
Reauthorization of TEA-21
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/
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/TRNJulyAug2012.pdf
http://www.fas.org/sgp/crs/misc/R40431.pdf