I-610 in Houston: the 610 Loop's congestion, trucks and Ship Channel bridge

The 610 West Loop between I-10 and I-69 has been the most congested road segment in Texas in each of the last three editions of the state’s top 100 list.¹ The loop is also Houston’s designated through route for trucks carrying hazardous materials, and its East Loop crosses the Houston Ship Channel on a bridge built in 1973.

610 West Loop: the most congested road segment in Texas

The Texas A&M Transportation Institute (TTI) measures congestion as annual hours of delay per mile. On the 3.62-mile West Loop segment from I-10 to I-69, that came to 1,729,469 person-hours in 2024, at a cost of $166.4 million in time and fuel.¹

TxDOT’s version of the list gives the segment a Texas Congestion Index of 2.58.² TTI defines an index of 1.40 as a 20-minute off-peak trip taking 28 minutes at the peak, so 2.58 works out to about 52 minutes for the same trip, by Texas Mobility Outlook’s calculation.³

TTI describes I-610 West as a road “where it is always rush hour,” with congestion outside the normal peaks made worse by crashes and stalled vehicles.⁴ It also flagged the segment as under construction during 2024, the year its 2025 ranking measures. The rebuilt I-69 interchange at the south end of the segment was finished Aug. 1, 2024.⁵

The North Loop West, from I-45 to I-10, ranks fifth and carries the highest congestion cost of any loop segment, $183.3 million. For trucks, TTI ranks the North Loop West sixth in Texas, the West Loop eighth, the North Loop East 19th and the East Loop 20th.¹

610 Loop traffic counts

The West Loop station north of I-10 averaged 303,669 vehicles a day in 2025, nearly unchanged from 2023. On the East Loop, the station near Cowart St rose 13.2% over the same two years, to 178,650 (Texas Mobility Outlook’s calculation from TxDOT counts).⁶

The Harris County Toll Road Authority’s 2023 screenline counts put 83,400 northbound and 89,300 southbound vehicles a day on the I-610 main lanes south of Market Street Rd.⁷

Truck traffic on the North and East Loop

TxDOT’s count on the North Loop East near Darien St on May 13, 2025 found 28,849 trucks, 18.31% of traffic. That is the highest single-day truck count among the Houston-area classification stations Texas Mobility Outlook compiled. The East Loop near Turning Basin Dr had the second-highest count, 26,852 trucks (15.03%), on the same day.⁸

The West Loop near W 11th St carried about twice the total traffic of the Darien St station, but 16,652 trucks, or 5.41%. The North Loop East count recorded 1.7 times as many trucks with about half as many vehicles overall (computed). These are raw single-day counts, not annual averages.

Port Houston and commercial truck traffic covers truck volumes on the roads that serve the port’s terminals.

610 Loop interchange projects

• I-69 Southwest Freeway interchange. Under construction from September 2017 and opened Aug. 1, 2024, about a year ahead of original expectations, Texas Highway Commissioner Bruce Bugg told Community Impact.⁵ The $259 million project, $87.5 million of it through Texas Clear Lanes, widened single-lane connectors to two lanes, rebuilt the West Loop main lane bridge, and added two detention ponds under the interchange and four pump stations.⁹
• SH 288 interchange (Cambridge St to Scott St). Finished with a ribbon cutting July 1, 2025. The $117 million project added eight direct-connect ramps between I-610 and SH 288; Texas Clear Lanes lists it at $116.9 million for 2018-2025.^10,11
• SH 35 and I-610. Under construction, 2022-2027, at $445 million. Texas Clear Lanes describes an eight-lane freeway with two-lane frontage roads on a new location, running from north of OST to Bellfort St, with direct connectors at SH 35 and I-610.¹¹

Sidney Sherman Bridge over the Ship Channel

The East Loop crosses the Houston Ship Channel on the Sidney Sherman Bridge, 1.5 miles north of SH 225. TxDOT’s bridge inventory lists it as built in 1973, carrying 10 lanes, with an overall condition class of fair. Its deck is rated 6, superstructure 5 and substructure 7, from a routine inspection on Dec. 10, 2024.¹²

The inventory’s most recent traffic figure is from 2020: 136,576 vehicles a day, 10,926 of them trucks (8.0%, computed).¹²

TxDOT’s project database carries a “Bridge Replacement” record for I-610 from north of Mississippi St to south of SH 225, the stretch that crosses the channel. It is in the “Planning, 10+ years” stage with a $1.6 billion estimate and a June 2038 estimated letting. The record, last updated Aug. 12, 2024, does not name the Sidney Sherman Bridge.¹³ Nearer-term records include LED safety lighting at the Ship Channel, estimated at $2.4 million for a December 2027 letting.¹³

Why hazmat trucks use the 610 Loop

A City of Houston ordinance dated March 4, 1970 designates the entire 610 Loop as a through route for non-radioactive hazardous materials. The same ordinance prohibits them on I-45 from Franklin St to US 59, on US 59 from I-45 to Buffalo Bayou, and on streets around the Texas Medical Center.¹⁵

The Houston Police Department says vehicles carrying hazmat “must use this 610 Loop route and not travel through the city.”¹⁶ Texas requires cities of more than 850,000 people to designate such routes.¹⁵ Under federal rules, a route takes effect only once the Federal Motor Carrier Safety Administration (FMCSA) publishes it in its national registry.¹⁷ Commercial vehicle safety in Houston covers the routing rules for carriers.

610 Loop crash data

TxDOT’s published tables do not separate I-610 from Harris County’s other interstates, which together recorded 134 deaths in 2025.¹⁸ A study commissioned by a bail bond company, as reported by CultureMap Houston, counted 43 fatal crashes on I-610 from 2019 to 2023, ranking it 131st among U.S. roads by total fatal crashes.¹⁹ That count does not adjust for the loop’s traffic. Houston’s most dangerous highways compares the published rankings. TxDOT’s county totals by road type are on the Harris County crash data page, and truck-involved crashes on Houston truck crash statistics.