Can You Sue a California City After a Dangerous Bike-Lane Crash? Tansavatdi and Design Immunity

What happened on Hawthorne Boulevard

On the afternoon of March 18, 2016, Jonathan Tansavatdi was riding his bicycle southbound on Hawthorne Boulevard in Rancho Palos Verdes. Most of Hawthorne has a bicycle lane, but the lane stops at Dupre Drive and does not restart until after Vallon Drive. The block in between pitches sharply downhill and curves to the right, and there is a right-turn-only lane at Vallon.

As Jonathan approached the intersection, he rode into the right-turn lane but continued straight through it. An 80-foot tractor-trailer was making a right turn from Hawthorne onto Vallon. Because of the trailer’s length, the truck began its turn to the left of the turn lane, cutting across it at a perpendicular angle. A witness following behind testified Jonathan had been traveling roughly 35 to 40 miles per hour and began honking to get his attention; he looked up about 40 feet out and slowed to perhaps 10 to 15 miles per hour before striking the side of the trailer. He died from his injuries.

His mother, Betty Tansavatdi, sued the City for a dangerous condition of public property under Government Code section 835 — alleging both that the City created a dangerous condition in designing the roadway and that it failed to adequately warn of it. Ten years and two appellate decisions later, that case has produced a published rule that will be quoted in every dangerous-roadway case filed in Los Angeles County.

How a claim against a public entity actually works

Under the Government Claims Act, a public entity is not liable for an injury except as provided by statute. Section 835 supplies that statute for roadway cases. A public entity may be liable for a dangerous condition of its property in two situations: where a government employee’s negligent act or omission created the condition (section 835(a)), or where the entity had notice of the condition and failed to protect against it (section 835(b)). “Protect against” expressly includes warning of a dangerous condition. A “dangerous condition” is one creating a substantial risk of injury when the property is used with due care in a reasonably foreseeable manner.

Even if you prove all of that, the entity can still raise immunities. Two matter here.

Design immunity — Government Code section 830.6

Design immunity protects public entities from liability for dangerous conditions “caused by the plan or design” of public property. The entity must establish three elements:

1. A causal relationship between the plan or design and the accident;
2. Discretionary approval of the plan or design prior to construction; and
3. Substantial evidence supporting the reasonableness of the plan or design.

Critically, design immunity is usually litigated on summary judgment, which lets the trial court find the defense established as a matter of law — before a jury ever sees the case.

Signage immunity — Government Code section 830.8

Separately, section 830.8 immunizes an entity for injury caused by the failure to provide traffic or warning signals, signs, markings or devices. The well-known exception is the “concealed trap”: liability can attach where a sign was necessary to warn of a dangerous condition that would not be reasonably apparent to, and would not have been anticipated by, a person using the roadway with due care.

What the Supreme Court had already decided

This is the second trip up for this case. In Tansavatdi v. City of Rancho Palos Verdes (2023) 14 Cal.5th 639 (“Tansavatdi I”), the California Supreme Court held that design immunity does not categorically preclude failure-to-warn claims involving a discretionarily approved element of a roadway. Relying on Cameron v. State of California (1972) 7 Cal.3d 318 and Flournoy v. State of California (1969) 275 Cal.App.2d 806, the Court reasoned that immunity for a government’s “active” negligence in creating an approved design does not necessarily immunize its “passive” failure to warn of the danger that design created.

But the Supreme Court attached two caveats that drive the 2026 decision. First, a plaintiff must prove the absence of a warning was an “independent, separate, concurring cause of the accident” — if the missing warning was not a substantial factor in causing the injury, the claim fails. Second, and decisively, the Court expressly left open “whether design immunity might apply if the public entity is able to show that the presence or absence of warning signs was part of the approved design.” In Cameron, the Court noted, the plaintiffs had specifically alleged the failure to warn was not part of any approved plan.

On remand, the City of Rancho Palos Verdes walked straight through that open door.

The City’s second summary judgment motion

The City came back with evidence of exactly what warnings existed on southbound Hawthorne approaching Vallon, and that each was part of its 2009 street resurfacing and restriping plans:

• Broken striping for 200 feet in advance of Dupre signaling the end of the bike lane;
• A yellow curve warning sign with a 35 mph advisory plate, plus “35” stenciled in white on the pavement in each lane;
• A pictorial truck-on-grade sign and an “8% GRADE” sign;
• Six equally spaced yellow-and-black chevron signs along the curve;
• A “signal ahead” warning sign about 570 feet north of Vallon, with “SIGNAL AHEAD” stenciled on the pavement, plus a flashing yellow beacon in the median;
• Right-turn-lane striping beginning 220 feet north of Vallon with painted arrows and two “RIGHT LANE MUST TURN RIGHT” signs.

The City’s traffic engineering expert testified each of these conformed to the California Manual on Uniform Traffic Control Devices (MUTCD). A former senior City engineer declared that in 2009 the City “considered what signage, striping and stenciling to include” and consciously chose to keep the existing warnings in place, making their retention part of the approved plans.

The plaintiff’s expert did not dispute that signs existed. He argued they were insufficient — the City should have added a radar speed feedback sign, a flashing warning beacon system, sharrow markings, and signs reading “BE PREPARED TO STOP” and “PROCEED AT OWN RISK.” That framing — there were warnings, but not the right ones — is what sank the claim.

The 2026 holding: “no warning” versus “not enough warning”

The Court of Appeal adopted a rule narrower than either side asked for. Its holding, in the court’s own structure: when (a) the public entity has provided some warning of the allegedly dangerous condition, and (b) that warning was included as part of a reasonable plan or design that would otherwise be entitled to design immunity under section 830.6, then (c) design immunity may apply — assuming every other requirement of design immunity is met.

The reasoning rested on three points. First, the “prime requisite” of design immunity is a design-caused accident; when warnings were part of the design and the complaint is that the design should have included different warnings, the accident is design-caused. Second, when a warning is provided as part of a design, its alleged inadequacy is hard to characterize as an “independent” or “separate” failing distinct from the design. Third, immunity here serves the doctrine’s separation-of-powers purpose — preventing juries from second-guessing risk judgments public officials already made.

The court was candid about what a trial would have looked like: the jury would not decide whether the City should have warned at all, because it plainly did. It would choose between the City’s flashing beacon and “SIGNAL AHEAD” signage and the plaintiff’s proposed radar feedback sign and “PROCEED AT OWN RISK” placard — “a fundamental question of traffic engineering.” The court also noted that in traffic cases the line between a “warning” and roadway architecture is genuinely blurry: are rumble strips a warning or infrastructure? Is lane striping a warning or a design project?

The court rejected the argument that its rule would gut failure-to-warn liability on every road, pointing to Anderson v. City of Thousand Oaks (1976) 65 Cal.App.3d 82, where a city posted no signs warning of a dangerous curve. “In cases where no warning has been provided of a dangerous condition,” the court wrote, “it is difficult to see how the purposes of design immunity are implicated.” The holding also aligns with Stufkosky v. Department of Transportation (2023) 97 Cal.App.5th 492, where Caltrans’s plans specified the quantity and placement of deer crossing signs and plaintiffs disputed only their adequacy.

What survives this decision — four openings that remain

For injured Angelenos and their families, Tansavatdi narrows one route but leaves several intact. A serious roadway case should be built around these:

1. The city provided no warning at all

This is the clean path. Where the entity never warned of the hazard, design immunity does not do the work, and the fight moves to section 830.8 signage immunity and its concealed-trap exception. The court was explicit that it was not disturbing Anderson.

2. There was no formal, discretionarily approved plan

Design immunity requires discretionary approval of a plan or design prior to construction. Where the entity cannot produce a formal plan adopting the feature, immunity fails — as in Cameron and Martinez v. County of Ventura (2014) 225 Cal.App.4th 364. But note the court’s caution: immunity is not limited to features the entity expressly considered, per Stufkosky, Rodriguez v. Department of Transportation (2018) 21 Cal.App.5th 947, and Hampton v. County of San Diego (2015) 62 Cal.4th 340.

3. No substantial evidence that the design was reasonable

The court stressed that “design immunity does not immunize truly unreasonable design, including the design of warnings.” The standard is generous to government but “not a limitless one” — see Davis v. Cordova Recreation & Park Dist. (1972) 24 Cal.App.3d 789. A design violating the MUTCD or accepted engineering standards is where this attack lives.

4. Loss of design immunity through changed conditions

This is the most important preserved theory, and the plaintiff in Tansavatdi did not invoke it. Under Baldwin v. State of California (1972) 6 Cal.3d 424 and the current text of section 830.6, when a public entity has notice that changed physical conditions have made an approved design dangerous in operation, it must act reasonably to correct the hazard and remains under a continuing duty to review its plan in light of actual operation. Immunity continues only for a reasonable period sufficient to obtain funds and carry out remedial work; where the entity cannot remedy the condition, immunity persists only so long as it reasonably attempts to provide adequate warnings. The court noted pointedly that the plaintiff “made no attempt to show that design immunity was lost due to a change in physical conditions.”

Between 2022 and 2023, years after the crash, the City lowered the advisory speed from 35 to 30 mph, added three chevron signs, and installed further warning signs. Subsequent remedial measures are not admissible to prove negligence, but a documented history of post-design collisions and changed traffic conditions is the raw material of a Baldwin theory — one that must be pleaded deliberately from the start.

The cost warning every claimant should read

The second half of the opinion is a lesson in litigation risk. In April 2018 the City served an offer to compromise under Code of Civil Procedure section 998 — a waiver of costs in exchange for dismissal and a general release, stated to be “in full settlement of this action.” It was not accepted. After winning summary judgment, the City sought over $79,000 in costs, including $36,372 in expert witness fees.

The plaintiff argued the offer was invalid because its “general release” reached claims beyond the lawsuit. The Court of Appeal disagreed: following Goodstein v. Bank of San Pedro (1994) 27 Cal.App.4th 899, because the offer said “in full settlement of this action” and did not expressly reach outside claims, the release was construed as limited to the current litigation. The $75,979.22 cost award stood.

The takeaway is blunt: rejecting a government defendant’s 998 offer in a case that turns on an immunity defense carries real financial exposure, and that calculation should be made with experienced counsel.

What to do if you or a family member was hurt on a Los Angeles roadway

• Calendar the six-month claim deadline immediately. Government Code section 911.2 generally requires a written claim to the public entity within six months of the injury for death and personal injury claims — before any lawsuit. This is the deadline that quietly kills most roadway cases.
• Identify every potential entity. A single LA corridor can involve the City of Los Angeles, LA County, a separate incorporated city, Caltrans, or a transit agency. Each requires its own claim.
• Photograph the signage that exists — and the signage that does not. After Tansavatdi, documenting the complete absence of any warning of the specific hazard is far more valuable than arguing existing signs were too small.
• Request records early. Public records requests for design and resurfacing plans, collision histories, speed surveys, prior complaints, and work orders are what prove notice and changed conditions.
• Do not rely on the police report’s fault conclusion. California follows pure comparative fault; a cyclist or pedestrian partly at fault can still recover, reduced by their share.
• Preserve the bicycle, helmet, and devices. There is almost always a private defendant alongside the public entity — and private defendants have no design immunity.

That last point deserves emphasis. Design immunity protects the government. It does nothing for the trucking company, the motorist, the delivery contractor, or the property owner whose overgrown hedge blocked a sight line. In Tansavatdi the plaintiff also sued the truck driver and trucking company. A well-built roadway case rarely rests on the public entity alone.

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