Access Management: South Carolina’s Experience Rick Werts Director of Traffic Engineering South...
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Transcript of Access Management: South Carolina’s Experience Rick Werts Director of Traffic Engineering South...
Access Management:
South Carolina’s Experience
Rick Werts
Director of Traffic Engineering
South Carolina Department of Transportation
Presentation OutlinePresentation Outline
• What is access management?
• Resources
• SCDOT’s experience• Current updates• School access design
• Conclusions
• What is access management?
• Resources
• SCDOT’s experience• Current updates• School access design
• Conclusions
What is Access Management?What is Access Management?
Access management is the systematic control of the location, spacing, design, and operation of driveways, median openings, interchanges, and street connections to a roadway. It also involves roadway design applications, such as median treatments and auxiliary lanes, and the appropriate spacing of traffic signals.
Access management is the systematic control of the location, spacing, design, and operation of driveways, median openings, interchanges, and street connections to a roadway. It also involves roadway design applications, such as median treatments and auxiliary lanes, and the appropriate spacing of traffic signals.
Additional ResourcesAdditional Resources
• Links to state DOT websites and manuals
• NCHRP research reports
• National conference information
• Past conference proceedings
• Outreach programs
• Training opportunities
• Links to state DOT websites and manuals
• NCHRP research reports
• National conference information
• Past conference proceedings
• Outreach programs
• Training opportunities
Graphics Slide BackgroundGraphics Slide BackgroundSCDOT’s ExperienceSCDOT’s Experience
• Increased growth in South Carolina
• Congestion has created a need for more specific access management guidelines
• Update current guidelines (1996) based on recommended practice from TRB’s Access Management Manual
• Increased growth in South Carolina
• Congestion has created a need for more specific access management guidelines
• Update current guidelines (1996) based on recommended practice from TRB’s Access Management Manual
Driveway Classification
Expected Trips
Low Volume
1-20 trips/day
1-5 trips/hour
Medium Volume
21-600 trips/day
6-60 trips/hour
High Volume
601-4,000 trips/day
61-400 trips/hour
Major Volume
>4,000 trips/day
>400 trips/hour
• Driveway design elements (width & radii) based on driveway classifications
• Driveway design elements (width & radii) based on driveway classifications
Driveway Design ElementsDriveway Design Elements
Driveway Classification Expected Trips
Low Volume1-20 trips/day
1-5 trips/hour
Medium Volume21-600 trips/day
6-60 trips/hour
High Volume
601-4,000 trips/day
61-400 trips/hour
Major Volume>4,000 trips/day
>400 trips/hour
Driveway Design ElementsDriveway Design Elements
Driveway Class Driveway Width (feet)Minimum Radius
Returns (feet)
Low Volume 10 – 24 15
Medium Volume 24 – 36* 30 (40 Recommended)
High Volume 36** **
Major Volume ** **
* A 36 ft. driveway is usually marked with two exit lanes of 11 ft. width, with the balance of 14 ft. used for a single, wide entry lane. A larger width will be required for a divided driveway design.
**Driveway widths and lane requirements are determined by a traffic study.
Throat LengthsThroat Lengths
Land Use Driveway Throat Length
Major entrance to a development with4 or more total lanes in the driveway
>300 ft, based on traffic engineering study
Regional Shopping Center (>150,000 sq. ft.)
250 ft.
Community Shopping Center (100,000-150,000 sq. ft.)
150 ft.
Small Strip Shopping Center 50 ft.
Commercial Developments (convenience stores, Gas Stations)
30 ft.
• Spacing based on speed limit and AADT• Spacing based on speed limit and AADT
Driveway SpacingDriveway Spacing
Posted Speed Limit (mph)
Minimum Driveway Spacing (ft) on
roadways with AADT > 2000
Minimum Driveway Spacing (ft) on roadways with AADT < 2000
30 160 75
35 220 125
40 275 175
45 325 225
> 50 400 275
Interchange AreasInterchange Areas
Distance(ft)
Description
X 750 Distance from the closest
interchange ramp to the first full access intersection
Y 325 Distance from the off-ramp
to the first right in, right out access point
Z 325 Distance between the last
right in, right out access connection and the on-ramp
New School SitesNew School Sites
• Access Problems due to:• Site Selection• Inadequate internal storage• Lack of turn lanes on roadway• No traffic engineer in planning process
• Access Problems due to:• Site Selection• Inadequate internal storage• Lack of turn lanes on roadway• No traffic engineer in planning process
New School SitesNew School Sites
• Planning Efforts undertaken:• Met with State Education Department• Expressed concern with site selection and school
layouts• Asked to be included in planning stages
• Planning Efforts undertaken:• Met with State Education Department• Expressed concern with site selection and school
layouts• Asked to be included in planning stages
• The Office of School Facilities Manual states:
The SCDOT shall be consulted for roadway improvements whenever stacking loops or access to a school is modified, or whenever a new school is planned, or an addition that increase the number of students is planned. Access to a school site shall be defined by the SCDOT Traffic Engineering Division as part of the encroachment permit process.
• The Office of School Facilities Manual states:
The SCDOT shall be consulted for roadway improvements whenever stacking loops or access to a school is modified, or whenever a new school is planned, or an addition that increase the number of students is planned. Access to a school site shall be defined by the SCDOT Traffic Engineering Division as part of the encroachment permit process.
School Access DesignSchool Access Design
• Conduct an initial site review with School District representatives to identify potential access locations and roadway improvements
• Review detailed plans and provide any recommendations needed for final approval prior to issuing permit
• Conduct an initial site review with School District representatives to identify potential access locations and roadway improvements
• Review detailed plans and provide any recommendations needed for final approval prior to issuing permit
School Access DesignSchool Access Design
• On-Site Stacking Lengths requirements
(900 ft-1,500 ft)
• Driveway Spacing requirements
(600 ft. min)
• On-Site Stacking Lengths requirements
(900 ft-1,500 ft)
• Driveway Spacing requirements
(600 ft. min)
School Access DesignSchool Access Design
• Driveway lane widths and corner radii• Driveway lane widths and corner radii
School Access DesignSchool Access Design
Results of Planning EffortsResults of Planning Efforts
• New schools open with minimal traffic problems
• No roads are blocked by stacking traffic
• New schools open with minimal traffic problems
• No roads are blocked by stacking traffic