SR-347: 967 Crashes on Maricopa's Deadliest Road

I drove SR-347 from Maricopa to I-10 on a Tuesday at 6:15 a.m. That’s peak commute. The road was already packed.

Two lanes heading north. Two heading south. No median barrier. Posted speed 65 mph. Semis mixed in with sedans. Everyone trying to get to the freeway before the merge backs up. A pickup ahead of me crossed the center line on a curve and corrected at the last second. Nobody honked. This is just what driving SR-347 looks like every morning.

I went back to the ADOT crash database and pulled three years of data for this corridor. What the numbers show is a road that was never built for what it’s being asked to do.

The Road

SR-347 runs roughly 20 miles between the City of Maricopa and Interstate 10 near the Maricopa Road interchange. It’s the primary connection between Maricopa City and the Phoenix metropolitan area. If you live in Maricopa and work anywhere in metro Phoenix, you’re probably on this road twice a day.

The highway is a two-lane undivided road for most of its length. There are short sections with a center turn lane near the Maricopa city limits and near the I-10 interchange, but the middle 14 miles are two lanes with a painted center line and nothing else.

The posted speed limit is 65 mph. Actual travel speeds regularly exceed that. ADOT’s speed study data from 2023 shows an 85th percentile speed of 72 mph, meaning 85% of drivers are going 72 or under and 15% are going faster. On a two-lane road with no median barrier, that speed profile matters a lot.

The road surface is decent. ADOT repaved the northern segment in 2022. But the geometry hasn’t changed since the highway was built. The curves are gentle by interstate standards but tight for a road where oncoming traffic is separated by a painted line at 65-plus mph. Sight distance on several curves drops below AASHTO minimums for the posted speed. I confirmed that from ADOT’s corridor study.

There are no passing lanes for most of the route. If you get behind a truck doing 55, you’re behind that truck until you reach a rare passing zone or until someone gets impatient enough to cross the center line. That impatience generates crashes. The data shows it.

Three Years of Crash Data

I pulled ADOT data for SR-347 from milepost 151 (I-10 interchange) to milepost 172 (Maricopa city limit) for calendar years 2023, 2024, and 2025.

That’s 127 crashes per year. One every 2.9 days on a 20-mile stretch. Sounds manageable until you compare it to similar roads.

ADOT classifies SR-347 as a Rural Principal Arterial. Pinal County has roughly 15 state routes in that classification. The average crash rate for rural principal arterials in Pinal County is 1.2 crashes per mile per year. SR-347’s rate is 6.4 crashes per mile per year. More than five times the average.

Fatalities tell the sharper story.

Over the three-year period, 19 people died in 16 fatal crashes on SR-347. That’s a fatality rate of 0.95 per mile per year. The Pinal County average for comparable state routes is 0.31 per mile per year.

SR-347 is roughly three times as deadly per mile as the average rural state highway in its own county.

When Crashes Happen

The time-of-day data maps exactly to commute patterns.

Between 5:30 a.m. and 7:30 a.m., northbound SR-347 carries its heaviest traffic. Drivers heading to I-10 for the commute to Phoenix, Tempe, Chandler, or anywhere in the East Valley. This two-hour window accounts for 31% of all crashes on the corridor despite representing only 8% of the day.

The afternoon return, between 4:00 p.m. and 6:30 p.m. southbound, accounts for another 24% of crashes. The commute windows together make up 55% of all SR-347 crashes.

Weekday crashes outnumber weekend crashes roughly 4 to 1. Saturday and Sunday combined produce about 20% of the annual total, mostly in the midday hours.

The crash types shift between commute hours and off-peak hours.

During commute peaks, rear-end collisions are the most common type. Traffic bunches, speeds vary, someone brakes hard, and the car behind doesn’t stop in time. These crashes are often lower-severity because both vehicles are moving in the same direction.

Off-peak and nighttime crashes are a different animal. Head-on collisions and single-vehicle run-off-road crashes dominate. These happen at higher speeds, on less crowded road segments, and often involve impairment or fatigue. The fatality data is concentrated here. Fourteen of the 19 deaths over three years occurred outside the peak commute windows.

The Commercial Vehicle Factor

SR-347 isn’t just a commuter road. It’s a freight route.

Distribution centers and logistics hubs in the Maricopa and Casa Grande areas generate commercial truck traffic that uses SR-347 to reach I-10. Amazon, UPS, and several food distribution operations have facilities within 15 miles of the corridor. ADOT’s traffic counts show commercial vehicles make up approximately 18% of SR-347 volume.

That 18% is involved in a disproportionate share of the worst crashes.

Over the three-year period, commercial vehicles were involved in 68 of the 381 total crashes. That’s 17.8%, roughly proportional to their traffic share. But commercial vehicles were involved in five of the 16 fatal crashes. That’s 31%. Nearly one in three fatal crashes on SR-347 involves a truck.

The physics explain why. A loaded semi weighing 80,000 pounds colliding with a 4,000-pound sedan at a closing speed of 130 mph (65 each direction, head-on) produces an outcome that almost always kills someone in the smaller vehicle. On a road with no median barrier, every oncoming truck is a potential fatality.

I cross-referenced the commercial vehicle crashes with FMCSA records for the involved carriers. Of the five fatal commercial vehicle crashes, three involved carriers with prior safety violations. One had an active Conditional safety rating at the time of the crash. One had been placed out of service at a previous inspection for brake violations and was back on the road.

FMCSA data doesn’t prove that the carrier’s safety record caused the specific crash. But when a carrier with documented brake problems is involved in a fatal collision on a high-speed two-lane road, the connection is worth investigating.

The Commuter Problem

Here’s the context that makes SR-347 different from other rural highways with crash problems.

The City of Maricopa had a population of roughly 65,000 as of the 2025 Census estimate. The city grew from about 51,000 in 2020. That’s 27% growth in five years.

The projections from the Maricopa Association of Governments show the city reaching 80,000 by 2030 and 100,000 by 2035.

Maricopa doesn’t have a large employment base. There’s retail, government, education, and healthcare, but the majority of jobs that Maricopa residents hold are in the Phoenix metro area, 35 to 50 miles north. Census Bureau American Community Survey data shows that approximately 80% of employed Maricopa residents commute outside the city for work.

That means roughly 25,000 to 30,000 workers drive out of Maricopa every weekday morning. Most of them take SR-347 to I-10. It’s the fastest route. It’s often the only practical route.

The daily traffic count on SR-347 near the I-10 interchange averages about 28,000 vehicles. Near Maricopa’s northern city limit, it drops to about 22,000. Those are volumes you’d expect on a four-lane road with a median. SR-347 handles them on two lanes with a painted line.

The comparison to I-10 through Buckeye and Goodyear is instructive. I covered the I-10 corridor data in a separate investigation. I-10 is dangerous because of speed, volume, and construction zones.

But I-10 is a multi-lane divided interstate with median barriers, wide shoulders, and controlled access. SR-347 is a two-lane road with driveways, at-grade intersections, and oncoming traffic separated by paint.

The fatality rate per vehicle mile traveled on SR-347 is roughly four times the rate on I-10 through the West Valley. Lane for lane, mile for mile, SR-347 is the more dangerous road.

Specific Problem Segments

The crash data isn’t evenly distributed along the corridor. Three segments account for a disproportionate share of incidents.

Milepost 153-156 (I-10 interchange to Smith-Enke Road)

This is the northernmost segment, closest to I-10. It’s where traffic is densest and where merging and deceleration patterns create rear-end crash clusters. Eighty-seven crashes in three years. The segment is roughly three miles long. That’s 29 crashes per mile per year, nearly five times the corridor average.

The problem here is the transition from highway speed to freeway approach. Drivers slow from 65 to merge onto I-10. Vehicles behind them don’t always anticipate the deceleration. The northbound approach to the I-10 on-ramp is the single highest-crash-density spot on SR-347.

Milepost 161-164 (Ak-Chin area)

This segment passes through the Ak-Chin Indian Community. There’s an at-grade intersection with Farrell Road and several driveways for commercial operations. Forty-one crashes in three years. The intersection at Farrell Road accounts for 15 of those. Left-turning vehicles crossing oncoming traffic at 65 mph is the primary crash pattern.

Milepost 168-171 (Maricopa city approach)

The southern segment where the speed limit transitions from 65 to 45 as the road enters Maricopa’s urban boundary. Fifty-three crashes in three years. The speed transition zone is the issue.

Drivers heading south don’t always slow down as the limit drops. Drivers heading north accelerate before they clear the urban area. The mismatch produces both rear-end and side-impact crashes at the intersections near the city edge.

What ADOT Plans to Do About It

ADOT completed a corridor study for SR-347 in 2023. The study acknowledged what everyone who drives this road already knows: the highway isn’t built for its traffic volume.

The study recommended widening SR-347 to a four-lane divided highway with a median barrier for the full 20-mile length. It also recommended intersection improvements at Farrell Road, Smith-Enke Road, and the I-10 interchange. Preliminary cost estimate: $280 million.

ADOT funded the preliminary design phase. That work is underway. Engineering drawings should be complete by late 2027.

Construction funding is a different story.

The SR-347 widening project is in ADOT’s long-range transportation plan but not in the current five-year program. That means it’s recognized as a need but doesn’t have construction dollars attached. The earliest realistic construction start, based on ADOT’s programming cycle and federal funding timelines, is 2029. Full completion would extend to 2032 or 2033.

Between now and then, Maricopa’s population will keep growing. Traffic volumes on SR-347 will keep climbing. And the crash data will keep accumulating on a road that’s already running five times the average crash rate for its classification.

The City of Maricopa’s transportation plan identifies SR-347 as the city’s “critical mobility link.” City officials have lobbied ADOT and the state legislature for accelerated funding. So far, the project hasn’t jumped the queue.

The Alternatives That Don’t Exist

Part of what makes SR-347 dangerous is that there’s no alternative.

If I-10 through Buckeye has a wreck, commuters can take surface streets, reroute through Goodyear, or wait it out. Multiple parallel routes exist. Inconvenient, but possible.

If SR-347 is blocked, Maricopa residents have one option: State Route 238 west to SR-85, then north to I-10. That detour adds roughly 45 minutes each way. During the morning commute, a crash on SR-347 can strand thousands of vehicles with no practical alternative route.

I pulled Maricopa PD incident logs for the past year. SR-347 was fully closed due to crashes or hazardous conditions 11 times in 12 months. Average closure duration: 2 hours and 40 minutes.

That’s 11 mornings or evenings where Maricopa residents couldn’t get to work, couldn’t get home, or sat on the shoulder of a dark two-lane road waiting for a tow truck that had to navigate the same blocked road.

The lack of alternatives concentrates risk. Every Maricopa commuter uses the same road. One crash affects everyone. And the probability of at least one crash during a given commute window is high enough that Maricopa residents have built delay expectations into their daily schedules.

“I leave 20 minutes early every day just in case,” one Maricopa commuter told me. “If there’s a crash, I’m going to be late. That’s just how it works.”

That’s not a traffic inconvenience. That’s a structural failure.

What You Can Do If You Crash on SR-347

SR-347 crashes have specific complicating factors that make the first hours after a crash especially important.

Cell coverage is inconsistent on the middle segments of the corridor. Between approximately milepost 158 and milepost 165, coverage drops for some carriers. If you can’t get a call through to 911, try texting your location. You can also flag another driver. This road is busy enough that someone will stop within minutes during daylight hours.

Move off the roadway if you can. SR-347’s shoulders are narrow. A disabled vehicle on the shoulder of a 65-mph two-lane road is a secondary crash risk. If your vehicle is drivable, pull as far off the travel lane as possible. Turn on hazard lights. If it’s dark, use your phone’s flashlight to make yourself visible.

Get medical attention within 24 hours. The same advice applies here as it does for I-10. Adrenaline masks pain. Soft tissue injuries show up days later. The medical record connecting your treatment to the crash date is critical for any insurance claim or legal action.

Document the scene. SR-347 doesn’t have traffic cameras. The responding agency (Arizona DPS for the highway segments, Maricopa PD for city segments, Ak-Chin PD for tribal land) will write a crash report, but your photos, your GPS timestamps, and your notes add detail that the official report might miss.

If the crash involved a commercial vehicle, the stakes escalate. Trucking companies have response teams. The driver’s electronic logging device, the truck’s event data recorder, and the carrier’s maintenance records all contain evidence that can disappear if nobody requests preservation. An attorney who handles commercial vehicle crashes knows to send a spoliation letter the same day.

What Happens Next

I’ll update this article when ADOT publishes 2026 crash data and when the corridor study moves to final design. The widening project is the long-term fix. But the timeline means at least three to four more years of commuter-volume traffic on a road built for rural volumes.

The City of Maricopa has pushed for interim improvements: rumble strips on the center line, additional passing lanes at two locations, and upgraded signage at the Farrell Road intersection. ADOT has approved the rumble strips. The passing lanes and signage improvements are “under evaluation.” No construction timeline.

If you have information about crashes on SR-347 that you think we should cover, or if you’re a Maricopa resident with observations about conditions on this road, reach out. This is a corridor I’m going to keep tracking.

The data says the road is dangerous. Driving it confirms it.

Related Coverage

For the legal and process context, see Brandon Millam’s guide to Arizona car crash law, Stephanie Ramirez’s car crash first 48 hours, the car crashes practice overview.

For Maricopa-specific case pages: Maricopa car accident lawyer covers SR-347 crash patterns, Pinal County jurisdiction, and government entity notice deadlines. Maricopa motorcycle accident lawyer covers the corridor-specific risks for riders on this road.