If you're designing a path of travel in California and you need the numbers fast: maximum running slope is 5% (1:20) for an accessible route and 8.33% (1:12) for a ramp. Maximum cross-slope is 2% (1:48) — everywhere, always, no exceptions. Landings are 60 inches by 60 inches minimum. Clear path width is 48 inches minimum. These are California CBC Chapter 11B requirements, and they're stricter than federal ADA on almost every dimension.

Now let's talk about why that 2% cross-slope is the number that humbles experienced civil engineers, and what to actually watch for when you're designing site plans in California.

what's an ADA Path of Travel, Exactly?

A path of travel is the continuous accessible route connecting an accessible parking stall, transit stop, or public right-of-way to the accessible entrance of a building. Under CBC 11B-206.2.1, every accessible space you provide — parking, drop-off, seating area — needs a path that connects to an accessible entrance.

It's the sidewalk in front of the door. It's the whole chain: from the stall, through the parking lot, across the drive aisle via a curb ramp, along the walkway, to the entrance threshold. Every link in that chain has to meet the slope and width requirements. One bad link breaks the whole route.

Running Slope: 5% for Routes, 8.33% for Ramps

CBC 11B-402.2 sets the maximum running slope for a walking surface at 5% (1:20). If you exceed that, it's no longer a walking surface — it's a ramp, and now the ramp rules apply.

Ramps under CBC 11B-405 are limited to 8.33% (1:12) maximum. The moment you go to 8.34% you've got a violation. That's not a lot of margin. On a 20-foot-long ramp run at exactly 1:12, your total rise is 20 inches. More than that and you need a landing and another run.

The practical implication: if your site has natural grades between 5% and 8.33%, you can use the slope as a ramp —, then you need to provide all the ramp hardware (handrails, landings, detectable warning surfaces). A lot of designers try to thread the needle by calling a sloped walkway a "ramped route" without adding those elements. DSA will catch it. City plan checkers catch it too, just less consistently.

The 2% Cross-Slope Rule: Why It's the Hardest Number in Civil Engineering

Federal ADA (2010 Standards Section 403.3) allows a 2% cross-slope on walking surfaces. California CBC 11B-403.3 matches that limit. So why does this one rule generate more RFIs and correction notices than almost anything else on a site plan?

Because 2% feels like nothing until you try to hold it across a real parking lot.

Most parking lots are graded at 1.5% to 5% in multiple directions to drain. The accessible route cuts across those drainage planes. Where the sidewalk runs perpendicular to the lot's drainage slope, the cross-slope on the walk is essentially the same as the lot's drainage slope. If the lot drains at 3%, your cross-slope is 3%. That's a violation.

Here's where it really gets painful: the 2% rule applies in all directions simultaneously. Your running slope can't exceed 5%, your cross-slope can't exceed 2%, and your diagonal resultant slope also has to stay compliant. On a site where grading is working hard to manage drainage and match existing curbs, that's a tight geometric constraint.

The only real solution is to design the accessible route grades explicitly in your civil grading plan — not as an afterthought, as a constraint that drives the grading design. If your accessible route can't hold 2% cross-slope where it naturally wants to fall, you need a retaining element, a change in alignment, or a curb to separate the path from the parking field drainage.

Landing Requirements: California Is Bigger Than Federal

Federal ADA requires 48-inch by 48-inch landings at the top and bottom of ramps, and at any change in direction. California CBC 11B-405.7 requires 60 inches by 60 inches. That's a meaningful difference when you're tight on space.

Landings are required:

Each ramp run can have a maximum rise of 30 inches (CBC 11B-405.6). After 30 inches of rise, you need a 60-inch landing before you can continue rising. On a steep site, you might be stacking several runs with landings between them. That geometry adds up fast — budget the horizontal distance early in your design.

Landings also have to be level. "Level" in CBC terms means no more than 2% in any direction — same as the cross-slope rule. A landing that's 3% in any direction is a violation, even if the ramp itself is fine.

Clear Path Width: 48 Inches in California

Federal ADA requires a minimum 36-inch clear width for accessible routes, with some exceptions. California CBC 11B-403.5.1 requires 48 inches minimum. That's a 12-inch difference that matters in tight retrofit situations.

In practice, most new construction targets 5 feet (60 inches) because it allows two wheelchair users to pass., on alterations and path of travel upgrades, you're sometimes working within an existing concrete matrix. Knowing the California minimum is 48 inches, not 36, helps you understand your actual compliance threshold versus your preferred design width.

The 48-inch width must be clear of all obstructions — columns, signage, furniture, plant boxes, utility covers, and anything else that protrudes into the path. If a light pole base is in the path, the 48 inches is measured around it, not through it.

Handrails on Ramps: Both Sides, 34 to 38 Inches, With Extensions

Under CBC 11B-405.8, ramps with a rise greater than 6 inches require handrails on both sides. Height: 34 to 38 inches above the ramp surface, measured to the top of the gripping surface.

The extensions are what most plans miss. At the top of a ramp run, the handrail has to extend horizontally 12 inches beyond the top edge of the ramp. At the bottom, the extension must be equal to the length of one ramp slope (the horizontal projection of the run) plus 12 inches. Those extensions can't project into any required clearance or create a hazard.

Gripping surface requirements: circular cross-sections 1.25 to 2 inches in diameter, or non-circular cross-sections with a perimeter between 4 and 6.25 inches and a maximum cross-section dimension of 2.25 inches. Standard 1.5-inch pipe handrail meets this. The fancy square tubing on architectural railing systems often doesn't — check it before it's in the submittal.

Detectable Warning Surfaces: Where They're Required

Truncated dome detectable warning surfaces are required under CBC 11B-705.1.2.5 at:

The domes are 0.2 inches high, 0.9 inches in base diameter, spaced 2.35 inches on center in a square grid. Color has to contrast visually with adjacent surfaces. In California, most jurisdictions require a yellow or brick-red dome on gray concrete. Check the local standards — some cities have specific color requirements called out in their standard plans.

Common mistake: putting detectable warning surfaces at the top of a curb ramp that's inside a parking lot drive aisle, not at a public street crossing. The requirement is at the boundary between pedestrian and vehicular ways. If your curb ramp terminates in a parking stall access aisle with a painted boundary, check whether that constitutes a "vehicular way" under your jurisdiction's interpretation. It usually does.

How DSA Enforcement Differs From City Enforcement

The Division of the State Architect (DSA) has jurisdiction over K-12 schools, community colleges, and state-owned facilities. DSA plan review is thorough on ADA path of travel — they will redline cross-slopes, landing dimensions, and handrail extensions. DSA field inspectors verify compliance during construction.

City building departments enforce CBC 11B on commercial and multifamily projects, the depth of review varies considerably. Some jurisdictions flag every cross-slope deviation. Others approve plans and rely on contractor compliance, catching problems only at final inspection — if then.

For our clients, the practical difference is this: on a DSA project, you need to show slope analysis and spot elevations that prove your path of travel holds 2% cross-slope. On a city commercial project, the burden is still on you legally, the enforcement mechanism is looser. We design to the standard regardless, because a deficient path of travel is a liability issue long after the permit closes.

Path of Travel Upgrade Obligations on Alterations

If you're altering a building in California, CBC 11B-202.4 requires that you bring the path of travel to the altered area into compliance — up to 20% of the cost of the primary alteration. This isn't optional, and it's about the work area. The path from the accessible parking to the altered space has to be evaluated and upgraded if it doesn't comply.

We've seen this catch clients mid-design when a tenant improvement budget didn't account for the exterior path of travel work. A $50,000 tenant improvement can trigger $10,000 in exterior accessible route upgrades. Budget for it before the contractor is priced.

What We Actually Check on Every Site Plan

Our site planning work always includes an explicit accessible route analysis: spot elevations along the path, cross-slope verification at parking lot drive aisle crossings, landing dimensions confirmed in plan and section, and handrail geometry checked against CBC 11B. We don't leave it for the plan checker to find.

If a project is heading into construction, our construction administration team checks path of travel grades during site visits — before the concrete is placed, not after. It's a lot easier to correct a grade stake than a finished slab.

If you're working through a path of travel problem on a current project, give us a call. The numbers are clear. Getting them to work on a real site is where experience matters.

Reco Prianto, PE is the principal civil engineer at Calichi Design Group. He has designed accessible routes on K-12 schools, multifamily projects, and commercial developments across California under DSA and local jurisdiction review.