Bollard Spacing: How Far Apart Should Bollards Be?

The standard bollard-to-bollard spacing for vehicle protection is 4 to 5 feet on center, with ADA pedestrian access requiring a minimum 36-inch clear opening between bollards anywhere a wheelchair, walker, or stroller may pass. K-rated perimeter lines have specific manufacturer spacing requirements that depend on the test certification. Cojo set 4-foot center-to-center spacing on a 12-bollard storefront line in Portland in February 2026 to balance vehicle-impact resistance against the ADA-compliant 36-inch pedestrian opening between adjacent units. This guide covers the spacing math by application.

For category context, see our What Are Bollards hub. For application-specific spacing, see Bollard Spacing Guide. For ADA-only clearance, see Bollards and ADA Accessibility Clearance.

What's the Standard Bollard Spacing?

Standard spacing for non-rated steel pipe bollards in vehicle-protection applications is 4 to 5 feet on center. That spacing math comes from two constraints:

1. Vehicle width. Most passenger vehicles are 70 to 80 inches wide. A 48-inch (4-foot) center-to-center line creates a clear opening of roughly 42 inches with 4-inch bollards -- narrow enough that a vehicle cannot fit between adjacent posts.
2. ADA pedestrian clearance. The U.S. Access Board ADA Standards Section 403.5 requires a minimum 36-inch clear width for accessible routes. A 48-inch center-to-center line meets that minimum with most bollard diameters.

For storefront protection where vehicle ramming is the primary threat, 4-foot spacing is the most common spec. For drive-thru lanes or parking-lot perimeters where the threat is wider vehicles or higher speeds, 5- to 6-foot spacing is acceptable.

How Does Spacing Change by Application?

Why Does ADA Set the Lower Limit?

The U.S. Access Board's ADA Standards under Section 403.5 establish the 36-inch minimum clear width for accessible routes. That number is the floor, not a target. Where a path exceeds 200 feet without a passing space, Section 403.5.3 requires a 60-inch passing space at intervals of no more than 200 feet.

In practice, that means a bollard line less than 200 feet long can use 36-inch openings throughout. A line over 200 feet needs at least one 60-inch gap (or another passing-space arrangement) per 200 feet of length.

For larger questions about ADA parking design, see our ADA parking requirements Oregon service article.

How Do You Measure the Clear Opening Between Bollards?

The clear opening is measured between the inside faces of adjacent bollards at the height a wheelchair occupies the path -- typically 27 to 32 inches above grade. For a 6-inch diameter bollard with 48 inches center-to-center, the math is:

• Center-to-center: 48 inches
• Bollard outside diameter: 6 inches
• Clear opening: 48 - 6 = 42 inches

That clears the ADA 36-inch minimum with 6 inches of margin. Drop the spacing to 42 inches center-to-center with the same 6-inch bollard and the clear opening drops to 36 inches -- still ADA-compliant but with no margin.

What's the Spacing for K-Rated Bollard Lines?

K-rated bollard spacing is controlled by the certified configuration tested under ASTM F2656. Each manufacturer's test certificate specifies the bollard centers used during the live-fire crash test, and field installation must match those centers within tolerance.

Typical K-rated spacing:

• K4 fixed bollards -- 48 to 72 inches on center
• K8 fixed bollards -- 48 to 60 inches on center
• K12 fixed bollards -- 36 to 60 inches on center
• K-rated retractable bollards -- per certified group configuration

Field-modified spacing voids the K rating. For sites that need both K rating and wider pedestrian openings, the answer is usually a passive K-rated planter or wedge barrier between bollards rather than wider bollard spacing.

Where Do Bollards NOT Belong?

Three placement mistakes show up repeatedly in our retrofit work:

1. Closer than 36 inches between bollards on a pedestrian path. Violates ADA Section 403.5 and creates a tripping/wheelchair hazard.
2. Inside ADA accessible parking spaces or access aisles. Bollards in the 96-inch standard space or the 60-inch access aisle violate ADA Section 502.
3. In the curb-ramp landing area. Curb ramps need a 36-inch by 36-inch level landing. Bollards there block accessible route continuity.

For Portland metro work where Cojo handles a lot of bollard layout, see Bollard Installation Portland. For the underlying ASTM standard, see ASTM F2656 Bollards Guide.

How Do You Lay Out a Bollard Line in the Field?

The field-layout steps that produce a clean, code-compliant bollard line:

1. Mark the centerline of the bollard run with chalk or paint.
2. Locate the first bollard position at one end, typically aligned with a fixed feature (column, building corner, curb edge).
3. Mark each subsequent bollard center at the chosen on-center spacing.
4. Verify clear openings between adjacent bollards exceed your minimum (36 inches for ADA, 38 inches for vehicle protection).
5. Cross-check against ADA path widths, parking-stall positions, and curb-ramp landings before drilling.
6. Adjust if any conflict exists -- shift the entire line or add an additional bollard to maintain spacing.

Cojo's storefront install in Portland used a 48-inch on-center spacing for the 12-bollard line at a multi-tenant retail center, with the line shifted 6 inches off the original chalk mark to clear a curb-ramp landing on the south end.

Get a Layout Review for Your Site

Bollard spacing is one of the most common code-compliance issues we find on existing installs. ADA violations and rejected K-rated certifications both trace back to bad spacing math. Cojo specs and installs bollards across Oregon and provides spacing-verification reviews on existing lines. Contact Cojo for a site assessment.