FDOT Standard Plans Index 544-001: Crash Cushion Details

Design Criteria

Design Criteria AASHTO Roadside Design Guide 4th Edition 2011 ; FDOT Design Manual (FDM) , FDM 215 ; AASHTO Manual for Assessing Safety Hardware, MASH 2016

Design Assumptions and Limitations

Design Assumptions and Limitations Index 544-001 is only applicable for permanent crash cushion installations which shield the ends of Concrete Barrier and Guardrail. For general usage information for crash cushions, see FDM 215 . For a listing of crash cushion types and the corresponding usage limitations, see the Approved Products List (APL) webpage.

A. Location: A crash cushion is located by the Crash Cushion Station, which corresponds to the end station of the connecting barrier. See the drawings in Index 544-001 for a depiction of the Crash Cushion Station for guardrail and concrete barrier connections.

Crash cushions are typically placed to shield the ends of barrier systems that are either providing median crossover protection or shielding against a hazard per Part B below. B. Length of Need: For positioning crash cushions to shield against hazards, follow the Length of Need (LON) method described in the SPI for Index 521-001 (Concrete Barrier) and the SPI for Index 536-001 (Guardrail).

It is assumed that the LON departure line is located at the Crash Cushion Station unless there are constrained conditions per Part F below. For more information, see the drawings in the Excel-based Design Tool for Index 521-001 (Concrete Barrier) and the Design Tool for Index 536-001 (Guardrail). C.

Test Level: Select the crash cushion’s crash-test level based on the following: • For design speeds ≤ 45 mph, use TL-2 or TL-3 • For all other design speeds, use TL-3 D. System Width: Select the crash cushion’s system width based on the following: • For connections to barriers with widths ≤ 2’-0” (i.e. standard concrete barrier and single or double-faced guardrail), use a Narrow System • For connections to barriers with widths > 2’-0”, use a Wide System Index 544-001 Crash Cushion Details Note: Wide systems should only be used when no other option is available (i.e., wherever possible, reduce the connecting barrier width to ≤ 2’-0”).

E. Length of End Treatment – Default Values: For crash cushions, the Length of End Treatment segment includes all proprietary elements of the design as shown in the APL drawing, including the manufacturer’s transition to guardrail if applicable. The downstream end of the Length of End Treatment is located at the Crash Cushion Station per Part A.

See the drawings in Index 544-001 for a depiction of the Length of End Treatment. The as-built Length of End Treatment will vary depending on the contractor’s choice of products from the APL. Because of this variability, the default lengths below should be used in the Plans to provide space for any crash cushion chosen by the contractor.

Where there is sufficient space available, select the following default Length of End Treatment: • For TL-2 Crash Cushions, assume the Length of End Treatment = 27’-6” • For TL-3 Crash Cushions, assume the Length of End Treatment = 27’-6” F. Constrained Conditions: Where conditions of a project do not provide adequate space for the barrier and crash cushion, the overall system length may be reduced with the following methods: 1. Upstream End Restriction – Modify LON Calculation: For reducing the required length from the upstream end, adjust the LON calculation so that the “Begin LON” point (i.e.

the point where the departure line intersects the barrier system) is located 18 feet upstream of the Crash Cushion Station location per Part A. See Part B for LON calculation details. 2.

Downstream End Restriction – Crash Cushion Length Restriction : For reducing the required length from the downstream end, place a Length Restriction on the location-specific Length of End Treatment. The Length Restriction is used to limit the assumed Length of End Treatment to shorter values which restrict the contractor’s choice of end treatments on the APL. In general, the Length Restriction value should still be large enough to accommodate two or more crash cushions on the APL.

For additional information, see the

Payment

Payment Item number Item Description Unit Measure 544-2-1 Crash Cushion, Optional, TL-2 Narrow EA 544-2-2 Crash Cushion, Optional, TL-2 Wide EA 544-3-1 Crash Cushion, Optional, TL-3 Narrow EA 544-3-2 Crash Cushion, Optional, TL-3 Wide EA See the BOE and Specification 544 for additional information on payment, pay item use, and compensation.

What your plans must show

Plan Content Requirements for this index — the SPI's checklist for designers.

• 1. * Location (Station and Side), See the Crash Cushion Station in Index 544-001
• 2. * Crash Cushion System Width (Narrow or Wide)
• 3. * Crash Test Level (TL-2 or TL-3, included with Pay Item name)
• 4. *Barrier Width (Inches)