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Instructions Text
  
ECF Lane Tapers
  

ECF Lane Tapers - Lane Added

This module calculates the taper length for adding a lane.  Use this calculator to determine the length required to transition between the original cross section to the cross section with the additional lane.  This assumes that the lane is added from the outer edge versus in the middle of the roadway, such as for a left-turn lane.

Number of lanes added: This is the total number of lanes for which the transition is needed.

Width of one lane: This is the width of the lane to be added.  If two or more lanes are added with unequal widths, use the average.

Design speed: Select the design speed.  If it is not known, use either the 85th percentile travel speed or the posted speed limit plus up to 10 additional mph.

The Lane Added Taper Length is the total length required for the taper.

Approved
ECF Lane Tapers
  

ECF Lane Tapers - Lane Dropped

This module calculates the taper length for dropping a lane.  Use this calculator to determine the length required to transition between the original cross section to the cross section after the lane reduction.  This assumes that the lane is dropped from the outer edge versus in the middle of the roadway, such as for a left-turn lane.

Number of lanes dropped: This is the total number of lanes for which the transition is needed.

Width of one lane: This is the width of the lane to be dropped.  If two or more lanes are dropped with unequal widths, use the average.

Design speed: Select the design speed.  If it is not known, use either the 85th percentile travel speed or the posted speed limit plus up to 10 additional mph.

The Lane Dropped Taper Length is the total length required for the taper.

 

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ECF Lane Tapers
  

ECF Lane Tapers Calculator 

This module calculates taper lengths for different scenarios typically encountered in an Entry Control Facility (ECF). These scenarios are not exclusive to ECFs, they are commonly encountered transitions, but frequently occur at ECFs.

This module is divided into four calculations: Lane added, lane dropped, lane redirected; and ID Check area widening.
  1. Select a case from the drop-down menu.
  2. Enter requested data for case selected.
  3. Click the "Calculate" button.
  4. The required minimum sight distance will be displayed in the white box.
  5. To remove all entries and calculations, click the "Reset" button.
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ECF Lane Tapers
  

ECF Lane Tapers - Lane Redirected

This module calculates the taper length for redirecting a lane.  Use this calculator to determine the length required to transition between the original lateral location of the lane to the new lateral location of a lane.  This calculator applies when the original and final lateral locations are parallel to each other.  This calculator does not apply when a curve is used, or when the original and final locations are not parallel to each other.

Width of Offset:  This is the total lateral distance of the shift.

Design speed: Select the design speed.  If it is not known, use either the 85th percentile travel speed or the posted speed limit plus up to 10 additional mph.

The Lane Redirected Taper Length is the total length required for the taper.

Approved
ECF Lane Tapers
  

ECF Lane Tapers - ID Check Area Widening

This module calculates the taper lengths for tapering from an approach zone into an ID check area, and from an ID check area into a response zone.  This considers a possible change in the number and width of lanes between these areas, as well as the presence of a guard booth.

Fill in the matrix for number of lanes and lane width in the approach zone, ID check area, and response zone.  Additionally, enter the width of guard islands in the ID check area. Guard islands are assumed to be used between lanes, and not needed for the left-most lane since guards would utilize the median.

Design speed: Select the design speed.  If it is not known, use either the 85th percentile travel speed or the posted speed limit plus up to 10 additional mph.

Widening can occur symmetrically from the middle or only to one direction.  Check the appropriate box.

The approach zone taper length is the total length of the taper to transition from the approach zone to the ID check area.

The response zone taper length is the total length of the taper to transition from the ID check area to the response zone.  Note that this calculation does not influence the location of active vehicle barriers and cannot be used for placement of active barriers.

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Visitor Center Parking
  

Visitor Center Parking

​This module calculates the suggested number of parking spaces for a visitor center.

Estimate the number of visitor center customers processed in the peak hour.  Note that the time that this occurs may not necessarily correspond with the peak of the ECF as a whole.  The number should be a maximum regularly-occurring peak.

Future growth is the amount of growth that the installation or the visitor center will experience.  This number inflates the peak hour processing to a projected demand.

Enter the processing rate in minutes.  This rate may vary between five and fifteen minutes depending on procedure and efficiency.

The staff parking demand is the parking for employees.  If each employee drives and parks at the visitor center, enter the typical number of employees.  If this is not the case, enter the number of parking spaces all employees may need.

The total parking demand is the resulting number.  Note that this does not include ADA requirements.

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