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.

www.accessmanagement.govwww.accessmanagement.gov

ResourcesResources

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

TRB’s Access Management ManualTRB’s Access Management Manual

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

Corner ClearancesCorner Clearances

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

Guidelines for School Transportation Design

Guidelines for School Transportation 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

ConclusionsConclusions

• Good planning yields good results

• Good access standards lead to less traffic congestion and lower vehicle crashes

• Good planning yields good results

• Good access standards lead to less traffic congestion and lower vehicle crashes