Interstate 10 in California
Interstate 10 (I-10) in California constitutes the state's portion of the transcontinental Interstate Highway 10, spanning 243 miles from its western end at State Route 1 in Santa Monica to the Arizona state line east of Blythe.[1] The route traverses urban expanses of Greater Los Angeles and the Inland Empire, then proceeds through the Coachella Valley and Colorado Desert, serving as a primary east-west corridor for both commuter traffic and freight transport linking coastal ports to interior regions.[2] Designated segments include the Santa Monica Freeway from the coast to Los Angeles' Alhambra district and the San Bernardino Freeway eastward through San Bernardino County, with the entire California alignment recognized federally as part of the Christopher Columbus Transcontinental Highway.[3] Construction occurred primarily between the late 1950s and 1970s as part of the national Interstate System initiated under the Federal-Aid Highway Act of 1956, incorporating earlier state highways and enabling rapid vehicular mobility across southern California's diverse terrain.[4] The highway handles substantial volumes, with average daily traffic reaching up to 280,000 vehicles in key urban stretches, underscoring its role as one of the state's busiest freight arteries amid persistent congestion challenges that have prompted ongoing capacity enhancements like express lanes.[5][6]Overview
Route Summary and Length
Interstate 10 (I-10) in California spans approximately 243 miles (391 km) from its western terminus at the junction with State Route 1 (Pacific Coast Highway) in Santa Monica to its eastern terminus at the Arizona state line near Blythe, where it crosses the Colorado River.[7] The route is maintained entirely by the California Department of Transportation (Caltrans).[7] The freeway begins in coastal Santa Monica and proceeds eastward through the densely urbanized Los Angeles Basin as the Santa Monica Freeway and San Bernardino Freeway, serving major population centers including downtown Los Angeles, El Monte, Pomona, and Ontario.[7] It then transitions into the Inland Empire region, passing San Bernardino, Redlands, and Beaumont, before ascending the San Gorgonio Pass and descending into the Coachella Valley through Banning, Palm Springs, and Indio.[7] The eastern portion traverses the Sonoran Desert via Chiriaco Summit, culminating at the state border east of Blythe.[7] This alignment connects the Pacific Ocean coastline with inland desert areas, facilitating transcontinental travel as part of the broader 2,460-mile I-10 corridor while accommodating heavy local freight and commuter traffic.[8] The mileage is derived from Caltrans postmile markers, spanning from Los Angeles County supplemental postmile S0.094 to Riverside County route postmile R156.492.[7]Strategic and Economic Importance
Interstate 10 in California constitutes a vital east-west freight corridor, connecting the Ports of Los Angeles and Long Beach—handling approximately 15 million twenty-foot equivalent units (TEUs) annually—to distribution hubs in the Inland Empire and onward to national markets.[2] As part of the Primary Highway Freight System under the National Highway Freight Network, it supports the efficient movement of imports comprising over 40% of U.S. containerized cargo, facilitating just-in-time logistics essential for Southern California's warehouse economy.[9][10] Annual average daily traffic volumes exceed 250,000 vehicles in Inland Empire segments, with truck traffic representing a significant proportion that drives regional commerce.[11] The corridor underpins substantial economic activity, including over 60,000 logistics jobs in Riverside-San Bernardino County and intercity trade valued at more than $50 billion between Los Angeles and adjacent inland areas.[2] Infrastructure enhancements, such as express lanes, are projected to yield $1.4 billion in freight benefits over 20 years by reducing delays and improving reliability for goods transport.[12] These elements position I-10 as a backbone for California's export-oriented industries, where disruptions propagate costs across supply chains dependent on timely delivery to eastern destinations. Strategically, I-10's role extends to national supply chain resilience, with bottlenecks like the I-10/I-15 interchange in Ontario ranking among the top 20 U.S. truck congestion points, exacerbating delays for cross-country freight.[13][14] The broader I-10 freight corridor contributes an estimated $1.38 trillion to the U.S. economy yearly, with California's segment critical for import processing and outbound shipments, rendering it indispensable for economic stability amid growing trade volumes.[15] Its integration into federal freight planning prioritizes investments to mitigate vulnerabilities from high truck volumes and urban density.[16]Route Description
Santa Monica Freeway Segment
The Santa Monica Freeway segment of Interstate 10 begins at its western terminus with State Route 1 (Pacific Coast Highway) in Santa Monica, California, near post mile 0.00.[17] The freeway initially passes through the McClure Tunnel before heading eastward along the northern edge of the West Los Angeles area.[18] Early exits include Cloverfield Boulevard at post mile 0.96 and Centinela Avenue at post mile 2.08, serving local traffic in Santa Monica and West Los Angeles.[19] At post mile 3.11, Interstate 10 intersects the San Diego Freeway (I-405), a major interchange facilitating travel to Los Angeles International Airport southward and Sacramento northward.[19] Continuing east, the route traverses Culver City with exits at National Boulevard (post mile 5.05) and Robertson Boulevard (post mile 5.76), then enters central Los Angeles via interchanges at La Cienega Boulevard (post mile 6.81), Fairfax Avenue (post mile 7.00), La Brea Avenue (post mile 8.27), Crenshaw Boulevard (post mile 9.23), and Arlington Avenue (post mile 10.16).[19] These exits connect to key commercial and residential districts amid dense urban development. Approaching downtown Los Angeles, the freeway features exits at Western Avenue/Normandie Avenue (post mile 10.66), Hoover Street (post mile 11.64), and a significant stack interchange with the Harbor Freeway (I-110) at post mile 12.68, providing access to San Pedro southward and Pasadena northward.[19] [20] Further east, exits include Maple Avenue (post mile 13.64), San Pedro Street (post mile 14.22), and Central Avenue (post mile 14.55), before a left-exit interchange with State Route 60 and I-5 south at post mile 16.23. The segment concludes at the I-5 interchange at post mile 18.39, transitioning into the San Bernardino Freeway amid high congestion volumes exceeding 18,000 vehicles per lane in peak periods.[19][20]San Bernardino Freeway and Downtown Los Angeles
Interstate 10 traverses the southern edge of Downtown Los Angeles on an elevated viaduct, providing key access to the city's central business district and surrounding neighborhoods. West of downtown, I-10 interchanges with the Harbor Freeway (I-110) near Exposition Park and the University of Southern California, facilitating southbound travel toward the Port of Los Angeles and Long Beach.[21] This segment features exits for local streets including Venice Boulevard, Crenshaw Boulevard, and downtown entrances at Flower Street and Figueroa Street, supporting high commuter volumes into the financial and government hubs.[7] Eastward, I-10 crosses the Los Angeles River and interchanges with the Hollywood Freeway (US 101) near the Civic Center, a direct ramp connection that links to Hollywood and Ventura to the northwest and Pasadena to the southeast.[21] The freeway maintains six to eight lanes through this urban core, elevated to minimize surface disruption amid dense skyscrapers and historic districts. Traffic engineering here accommodates over 200,000 vehicles daily, with the structure designed in the 1950s to handle postwar suburban expansion.[22] The segment culminates at the East Los Angeles Interchange southeast of downtown, a sprawling junction connecting I-10 to I-5, State Route 60, and the southern end of US 101. This complex features multiple stacked ramps and direct connectors, handling approximately 400,000 vehicles per day as a critical gateway to the Inland Empire and Orange County.[21] East of this interchange, I-10 assumes the San Bernardino Freeway designation, descending slightly into the flatter terrain of East Los Angeles and passing through Boyle Heights with exits for 1st Street and Mission Road before entering Monterey Park.[7] The transition marks the shift from coastal urban density to industrial and residential suburbs, with the freeway carrying US Routes 60, 70, and 99 alignments from its pre-Interstate era.[23] This portion of I-10, originally part of the Ramona Freeway built between 1940 and 1960, exemplifies early California freeway design with concrete beam bridges and minimal medians to maximize capacity in constrained rights-of-way.[22] Ongoing maintenance addresses seismic vulnerabilities, given the route's proximity to the Puente Hills fault.[7]Inland Empire and Riverside County Segments
Interstate 10 enters San Bernardino County from Los Angeles County near Montclair, continuing eastward through the Inland Empire region for approximately 37 miles to the Riverside County line near Redlands.[24] The freeway features six to eight general-purpose lanes, with recent additions of express lanes in both directions along a 33-mile stretch from the county line to Redlands to improve traffic flow and reliability for commuters and freight haulers.[6] A key feature is the four-level stack interchange with Interstate 15 near the Ontario-Fontana border, which handles heavy volumes connecting to Las Vegas and San Diego.[25] The route passes through urban and suburban areas, including Upland, Rancho Cucamonga, Fontana, Rialto, Colton, and San Bernardino, where it intersects Interstate 215 and State Route 210, providing access to regional centers and the University of Redlands area.[25] Truck climbing lanes have been extended from Live Oak Canyon Road eastward to the Riverside County line to enhance safety by separating heavy vehicles from passenger traffic on uphill grades.[26] Entering Riverside County near Calimesa and Yucaipa, I-10 proceeds through Beaumont, where State Route 60 terminates in a partial cloverleaf interchange, and Banning, serving as a gateway to the Coachella Valley.[25] The freeway then climbs the San Gorgonio Pass, a narrow corridor prone to high winds between the San Bernardino and San Jacinto Mountains, before descending into Palm Springs, Cathedral City, Rancho Mirage, Palm Desert, Indian Wells, Indio, and Coachella.[27] In this eastern segment, I-10 transitions from valley terrain to desert landscape, intersecting State Route 111 and other local routes, and includes rehabilitation projects spanning 13 miles near Coachella for pavement and safety upgrades.[28] The route continues approximately 100 miles across Riverside County to the Arizona state line near Ehrenberg, facilitating east-west trade and tourism.[29]Operational Features
Express Lanes and Tolling Systems
The Metro ExpressLanes on Interstate 10 operate as high-occupancy toll (HOT) lanes managed by the Los Angeles County Metropolitan Transportation Authority (Metro), spanning approximately 14 miles along the San Bernardino Freeway from near the Pomona Fairplex eastward to the I-605 interchange in Baldwin Park.[30] These lanes opened to traffic on February 23, 2013, following construction that began in 2011 as part of a broader program to implement congestion pricing for improved flow.[31] Operation occurs 24 hours per day, seven days per week, with physical separation from general-purpose lanes via double solid white lines that prohibit crossing except at designated entry and exit points.[32] Vehicles with three or more occupants (HOV 3+) qualify for toll-free use at all times when equipped with a FasTrak Flex transponder set to the correct occupancy; vehicles with two occupants (HOV 2+) pay a discounted toll, while solo drivers pay the full dynamic rate.[32] Tolls are electronically collected via FasTrak, California's statewide system, with rates varying in real-time based on traffic demand to maintain speeds above 45 mph in the lanes, displayed on overhead signs at entry points.[33] As of October 6, 2025, the maximum toll rate stands at $3.10 per mile, adjusted periodically to cover operations and fund transit improvements.[34] Metro has proposed extending these lanes eastward from the I-605 to the San Bernardino County line, with environmental review ongoing and construction potentially starting in 2029.[35] Further east, the San Bernardino Associated Governments (SANBAG, now SBCTA) operates the SB Express Lanes on I-10 as a separate HOT system, with Phase 1 covering 10 miles from the Los Angeles County line to the I-15 interchange in the Inland Empire region.[14] This segment opened in late August 2024, utilizing converted high-occupancy vehicle (HOV) lanes with electronic tolling enforced via FasTrak for optimal pricing.[14] Similar to the Metro system, HOV 3+ vehicles travel toll-free with a Flex transponder, while fewer occupants incur dynamic tolls posted at entry gantries, aimed at preserving lane capacity and reliability.[36] Phase 2, extending 11.1 miles from I-15 to Pepper Avenue in Colton, is in preparation, with toll collection processed through regional partners like The Toll Roads agency.[14] No other tolled express lanes exist on I-10 within California, though the systems interconnect at county lines to facilitate regional traffic management.[37]Major Interchanges and Structures
Interstate 10 in California includes several multi-level interchanges designed to handle high traffic volumes, particularly in the Los Angeles Basin and Inland Empire regions. These structures feature stack and cloverleaf configurations to minimize weaving and support commuter, freight, and regional travel demands. The I-10/I-405 interchange in western Los Angeles links the Santa Monica Freeway with the San Diego Freeway, providing essential connectivity for traffic bound to Los Angeles International Airport and southern coastal areas. Caltrans projects have enhanced this junction, including HOV lane additions completed in 2015 to improve flow from Burbank Boulevard to the interchange.[38] The East Los Angeles Interchange forms a vast complex southeast of downtown where I-10 converges with I-5, US 101, and SR 60, managing intense urban traffic volumes. This junction spans multiple levels and connectors, with Caltrans referencing it in operational updates for I-10 maintenance and recovery efforts.[39] Eastward, the I-10/I-15 interchange in San Bernardino County serves as a critical freight gateway, accommodating approximately 50% of interstate truck traffic entering or exiting Southern California. San Bernardino Associated Governments (SBCTA) oversees expansions here, including express lanes extending from the interchange to address congestion in logistics-heavy corridors.[14][40] Notable structures along I-10 primarily consist of bridges and viaducts documented in Caltrans inventories, with rehabilitation projects focusing on pavement and overcrossings like the Mt. Vernon Avenue structure to support widening initiatives. No major tunnels exist on the I-10 alignment itself, though the adjacent McClure Tunnel on SR 1 connects Pacific Coast Highway near the western terminus.[41][42][18]History
Planning and Pre-Interstate Era
The development of the highway corridor now comprising Interstate 10 (I-10) in California originated in the state's proactive freeway planning during the 1940s, predating the federal Interstate Highway System authorized by the Federal-Aid Highway Act of 1956. California, facing rapid postwar population growth and automobile dependency, initiated comprehensive regional plans to construct limited-access expressways. The Los Angeles Regional Planning Commission's Master Plan of Metropolitan Los Angeles Freeways, adopted in 1947, outlined an interconnected network including east-west routes essential for transcontinental connectivity, incorporating alignments that would later form I-10's Santa Monica and San Bernardino segments.[43][44] This state-led initiative was bolstered by the Collier-Burns Highway Act of 1947, which allocated $300 million in fuel tax revenues for freeway bonds, prioritizing urban congestion relief over rural roads.[45] The western portion, designated as the Santa Monica Freeway, was envisioned as early as 1940 to link downtown Los Angeles to the Pacific coast, addressing bottlenecks on surface arterials like Wilshire and Olympic Boulevards. Planners proposed a new alignment south of these streets to minimize residential disruption while enabling high-speed travel, initially naming it the Olympic Freeway in alignment with the 1932 Olympics' legacy.[44] By the mid-1940s, engineering studies emphasized grade-separated interchanges and multi-lane designs, drawing from early successes like the 1940 Arroyo Seco Parkway.[43] The 1947 master plan formalized this as a coastal artery intersecting north-south corridors, with preliminary right-of-way acquisitions beginning in the late 1940s despite local opposition over displacement.[46] Eastward, the San Bernardino Freeway corridor built upon existing infrastructure, including the Ramona Parkway established around 1943 as Southern California's first expressway segment, providing limited access from Los Angeles to the Pomona Valley.[47] This overlaid parts of U.S. Route 66 (US 66), which had served east-west travel since 1926 via Foothill Boulevard and surface routes through San Bernardino, handling increasing freight and tourism volumes but plagued by at-grade intersections and wartime overloads.[48] The 1947 plan extended this into a full freeway to the Inland Empire, integrating with U.S. Route 60 alignments near Pomona for continuity toward Arizona, with state engineers prioritizing upgrades to divided highways by the early 1950s.[45] These efforts reflected causal priorities of economic expansion, as California's agricultural and industrial hubs demanded reliable arterials, though planning documents understated long-term urban sprawl effects.[49]Construction and Early Operations (1950s-1970s)
Construction of Interstate 10 (I-10) in California gained momentum after the Federal-Aid Highway Act of 1956, which allocated federal funds covering 90 percent of interstate costs, enabling upgrades to existing routes and new builds.[50] The eastern San Bernardino Freeway segment, originally aligned with U.S. Routes 60, 70, and 99 along Ramona Boulevard and related arterials, had early freeway elements dating to the 1930s but saw significant expansion in the 1950s. A 13.4-mile stretch from Pomona to Ontario opened on November 16, 1954, followed by completion between San Dimas and West Covina by 1956 and a continuous 60.2-mile corridor from Los Angeles to Colton by March 3, 1960.[7] Renamed the San Bernardino Freeway on November 24, 1954, this portion was approved as a chargeable interstate on September 15, 1955, reflecting California's preemptive freeway investments ahead of national standards.[7] Initial operations emphasized efficient east-west connectivity, with the 1956 opening celebrated for reducing travel times across the Inland Empire amid postwar suburban growth.[51] The western Santa Monica Freeway, planned as the Olympic Freeway but renamed on April 25, 1957, broke ground on June 17, 1957, with the first viaduct over the Los Angeles River.[44][7] Adopted as a freeway route in 1954 along former Legislative Route 173 and State Route 26 (Olympic Boulevard), construction proceeded in phases despite local opposition to routing through established neighborhoods, which led to displacements of thousands of residents and physical division of communities by 1961.[44][7] The easternmost segment opened and was dedicated by Governor Edmund G. Brown on December 4, 1961, linking to the San Bernardino Freeway and prior U.S. 101 connections in East Los Angeles.[44][7] Further westbound extensions followed: August 16, 1962, for a downtown-adjacent section; October 1964 to La Cienega Boulevard; January 29, 1965, for 4.5 miles to Bundy Drive; and full completion to State Route 1 in Santa Monica on January 5, 1966.[44][7] Early operations integrated I-10 into Los Angeles' burgeoning freeway network, which added over 500 miles regionally between 1950 and 1970, facilitating rapid commuter and freight movement but prompting immediate traffic volume increases and calls for capacity enhancements.[52] Eastward, desert segments east of Indio upgraded to freeway standards by 1964, with additional openings through Chuckwalla Valley in 1969 and to Blythe outskirts in 1970, solidifying trans-regional utility despite environmental and land-use hurdles.[7] These phases marked I-10's transition from segmented arterials to a cohesive interstate, underscoring engineering feats like elevated structures amid urban density.[44]Expansions, Renaming, and Modernizations (1980s-2000s)
In the 1990s, Interstate 10 underwent significant modernization efforts, particularly in response to seismic vulnerabilities exposed by major earthquakes. Following the 1994 Northridge earthquake, which damaged multiple structures on the Santa Monica Freeway segment, the California Department of Transportation (Caltrans) implemented a rapid reconstruction program. Crews repaired and retrofitted affected viaducts and connectors using prefabricated components, extended work hours, and streamlined permitting, completing the work in 66 days—a record for such a project that minimized economic disruption in the Los Angeles region.[53] This effort included seismic upgrades to bridges and overpasses along I-10, aligning with broader Caltrans initiatives post-Loma Prieta (1989) and Northridge to enhance structural resilience through base isolation and damping systems.[53] Expansions during this era were more incremental than transformative, constrained by urban density, environmental regulations, and funding limitations. In the Inland Empire, select widening projects added auxiliary lanes and improved interchanges in San Bernardino County during the late 1990s and early 2000s to accommodate freight traffic from growing logistics hubs, though full mainline expansions were deferred in favor of high-occupancy vehicle (HOV) lane extensions from earlier 1970s pilots.[54] These upgrades focused on operational efficiency rather than capacity increases, reflecting Caltrans' shift toward multimodal planning amid rising congestion.[55] Renamings in the 2000s honored notable figures without altering route alignments. In 2002, the California State Legislature designated the segment of I-10 from Interstate 405 to the junction with U.S. Route 101 as the Rosa Parks Freeway via Assembly Concurrent Resolution 134, recognizing the civil rights activist's legacy.[56] Concurrently, a 35-mile (56 km) portion east of Palm Springs, from State Route 111 to Dillon Road, was named the Sonny Bono Memorial Freeway to commemorate the former congressman and entertainer's contributions to regional infrastructure and environmental policy.[56] These designations, codified in state law, appeared on signage but did not involve physical changes to the highway.Recent Developments and Improvements (2010s-2025)
In the 2010s and early 2020s, the California Department of Transportation (Caltrans) and regional agencies focused on managed lanes and widening to address congestion on I-10 through Los Angeles and San Bernardino counties. The I-10 ExpressLanes, initially operational in segments east of Los Angeles since 2013, saw planning for eastward extensions to improve traffic flow and encourage carpooling between I-605 and the Los Angeles-San Bernardino county line; however, as of late 2024, this extension remained in the environmental review phase with potential funding discussions ongoing.[35][57] A major advancement occurred in San Bernardino County with the I-10 Corridor Project Phase I, which added two tolled express lanes in each direction over 10 miles from the Los Angeles county line to I-15, including auxiliary lanes for better access. Construction began in spring 2020 at a cost of $929.2 million, funded by federal, state, and local sources including Measure I sales tax revenues, and the lanes opened to traffic on August 29, 2024, aiming to reduce bottlenecks amid projected 38% population and 54% employment growth by 2040 in affected cities.[58][14] In July 2025, a new truck climbing lane opened east of San Bernardino following repaving of the median, which began construction in March 2024 to enhance safety for heavy vehicles.[59] Pavement rehabilitation efforts addressed deterioration across eastern segments. Caltrans completed the I-10 Tune-Up project, rehabilitating approximately 20 miles of damaged concrete slabs in Riverside County to extend service life and improve ride quality.[60] In the Blythe area near the Arizona border, ongoing work since the early 2020s includes pavement overlay, safety enhancements, and beautification, with eastbound detours and lane closures continuing into October 2025.[61][62] The I-10 Desert Rehabilitation project repaired asphalt concrete pavement over 30 miles between Desert Center and Blythe while adding a new eastbound truck climbing lane for safety.[28] On November 11, 2023, an arson fire damaged a section of I-10 under an overpass in downtown Los Angeles, affecting support columns and requiring closure of multiple lanes and ramps. Caltrans crews conducted 24/7 inspections and repairs, including concrete pouring and structural reinforcements, reopening the full freeway on November 20, 2023—11 days ahead of the initial three-to-five-week estimate—through expedited processes and state emergency declarations.[63][64] The incident prompted an after-action review highlighting needs for better under-freeway land management and inspections, though no widespread structural retrofits were immediately implemented on I-10.[65]Incidents, Safety, and Maintenance
Major Accidents and Structural Failures
The most prominent structural failure along Interstate 10 occurred during the Northridge earthquake on January 17, 1994, when a magnitude 6.7 event centered near Reseda caused the partial collapse of an elevated section of the Santa Monica Freeway (I-10) between La Cienega Boulevard and Robertson Boulevard in Los Angeles. Seismic forces exceeded the capacity of the reinforced concrete columns, which lacked sufficient shear reinforcement and transverse steel, leading to brittle failure and the dropping of a 12-span segment onto the roadway below. Although no fatalities resulted directly from the collapse, the event contributed to broader earthquake-related disruptions, including the failure or partial collapse of seven freeway bridges statewide, and halted traffic on this critical artery for months.[66][67] The damaged section was rebuilt in a record 66 days through accelerated construction methods, including 24-hour operations and prefabricated components, at a cost exceeding $20 million.[68] Beyond seismic events, Interstate 10 has experienced severe multi-vehicle accidents due to factors like weather, high speeds, and congestion. On April 29, 1999, heavy rain triggered multiple pileups involving up to 150 vehicles across a several-mile stretch near Pomona, injuring approximately 70 people, some critically, and closing lanes for hours; the crashes stemmed from hydroplaning on slick pavement amid dense traffic.[69] Such incidents underscore I-10's vulnerability, with data indicating it ranks among California's deadliest freeways, accumulating dozens of fatal crashes over stretches in Los Angeles and San Bernardino Counties between 2010 and 2020, often linked to impaired driving and poor visibility.[70] No single non-seismic structural collapse has matched the 1994 event's scale, though ongoing wear from heavy truck traffic has prompted inspections revealing deficiencies in older bridges.[71]Arson Fire and Subsequent Reforms (2023-2024)
On November 11, 2023, a fire ignited by arson in storage yards beneath an elevated section of Interstate 10 (I-10) in downtown Los Angeles damaged approximately one mile of the freeway between Alameda Street and the interchange with Interstate 110, leading to its indefinite closure in both directions.[72][73] The blaze, which started around 1:00 a.m. in areas leased by Caltrans to businesses storing wooden pallets, lithium-ion batteries, and construction materials, spread rapidly and was exacerbated by exploding hand sanitizer containers, requiring over 200 firefighters to extinguish it by midday.[74][72] Initial assessments indicated structural damage to support columns and the roadway deck, prompting Governor Gavin Newsom to declare a state of emergency on November 12 to expedite repairs and resource allocation.[75] California Highway Patrol and fire investigators confirmed arson as the cause within days, identifying a person of interest via surveillance footage showing a man pushing a shopping cart with combustible materials near the site; Cal Fire offered a reward for information leading to an arrest.[76][73] The closure disrupted commutes for an estimated 300,000 daily vehicles, causing widespread traffic congestion, but Caltrans accelerated repairs using 24-hour crews and federal aid, reopening the full section by November 21—about 10 days ahead of the initial 3-5 week estimate.[77][78] A California Governor's Office of Emergency Services after-action report highlighted successes in rapid response coordination but identified gaps in pre-fire risk mitigation under the freeway.[65] Post-incident inspections revealed Caltrans' infrequent and inconsistent oversight of leased properties contributed to the fire's severity, as hazardous materials accumulated without regular checks despite known risks in urban under-freeway lots.[79][80] A June 2024 Caltrans inspector general audit criticized the agency's failure to enforce lease terms prohibiting flammables, noting similar hazards at dozens of other sites statewide, including pallets and debris under freeways.[79][81] In response, Caltrans implemented new safety protocols, including pausing new leases for high-risk lots, mandating quarterly inspections, and recommending bans on combustible storage like wooden pallets under elevated structures; by February 2024, agency reviews expanded to prohibit such materials and enhance fire suppression requirements in leases.[80][82] These measures aimed to prevent recurrence without broader legislative changes, though critics argued they addressed symptoms rather than systemic underfunding of infrastructure maintenance.[83]Ongoing Maintenance Challenges and Criticisms
Interstate 10's maintenance is strained by its aging concrete infrastructure, originally constructed in the mid-20th century, which experiences accelerated deterioration from daily traffic volumes often surpassing 250,000 vehicles, including substantial freight hauling. Caltrans conducts periodic pavement rehabilitations to mitigate cracking and slab damage, as evidenced by the I-10 Tune Up project spanning approximately 20 miles in eastern Los Angeles County, where damaged concrete slabs were replaced to restore structural integrity. Similarly, the I-10 Desert Rehabilitation project addressed 13.6 miles of worn pavement in Riverside County through slab repairs, lane additions for trucks, and safety enhancements like clear recovery zones, reflecting the highway's vulnerability to heavy axle loads from interstate commerce.[60][84][28] Seismic vulnerabilities pose another persistent challenge, given the route's traversal of fault-prone regions; Caltrans has prioritized retrofitting bridges and overpasses, such as the 2018 Interstate 10 Seismic Retrofit at the Santa Ana River bridges, which involved widening pier walls across multiple sections to bolster collapse resistance during earthquakes. Statewide, Caltrans' retrofit program has installed cable restrainers on numerous structures since the 1990s, yet full implementation along I-10 lags due to the scale of over 100 bridges and the need for traffic-disruptive work, with ongoing assessments highlighting incomplete coverage on older viaducts. The American Society of Civil Engineers rated California's bridges at a C grade in 2021, citing seismic risks and deferred upgrades as key factors exacerbating potential failures on high-volume corridors like I-10.[85][86][87] Criticisms center on Caltrans' oversight lapses and inadequate funding allocation, exemplified by a June 2024 state audit that faulted the agency for neglecting mandatory annual inspections of leased properties beneath I-10, enabling hazardous material storage that fueled the 2023 fire and prolonged closures. This incident underscored systemic inspection shortfalls, with the audit recommending procedural reforms that Caltrans has partially implemented but not fully resolved, as evidenced by continued lane reduction schedules for maintenance in 2025. Broader critiques from transportation evaluations, including Caltrans' own 2024-25 Performance Benchmark Report, reveal uneven progress in eradicating a statewide deferred maintenance backlog, attributed to revenue declines from fuel-efficient vehicles and electric adoption eroding gas taxes, which forces reactive rather than preventive strategies and inflates future repair costs.[81][88][89]Economic and Societal Impacts
Contributions to Commerce and Mobility
Interstate 10 in California functions as a critical artery for freight movement, linking the Ports of Los Angeles and Long Beach—handlers of over 40% of U.S. containerized imports—to inland distribution centers and eastward routes.[10] This corridor supports the trucking of goods from coastal terminals through the Los Angeles Basin and into the Inland Empire, where warehouses process imports for national distribution, reducing reliance on congested rail alternatives and enabling just-in-time logistics.[6] Daily freight volumes on I-10 contribute to Southern California's logistics sector, which employs over 900,000 workers and accounts for 13.1% of regional GDP, underscoring the highway's role in sustaining trade-dependent economic activity.[90] As one of California's busiest freight freeways, I-10 accommodates average daily traffic exceeding 280,000 vehicles, with a substantial portion comprising heavy trucks transporting commodities like electronics, apparel, and consumer goods from port gateways.[5] Designated as a Critical Highway Freight Corridor, it facilitates efficient goods flow that bolsters supply chain reliability, directly impacting industrial competitiveness by minimizing delays in high-volume corridors connecting urban ports to rural and interstate networks.[16] The highway's alignment through densely populated counties enables access to manufacturing and warehousing hubs, generating economic multipliers through reduced shipping costs and faster delivery cycles compared to pre-interstate surface routes.[91] In terms of mobility, I-10 enhances personal and commuter transport across Southern California, spanning from Santa Monica through downtown Los Angeles to the Arizona border and serving over 263,000 vehicles daily in key Inland Empire segments.[11] By providing high-capacity access between employment centers in the coastal metropolis and affordable housing in Riverside and San Bernardino counties, it has historically cut travel times, fostering workforce mobility and regional integration since its expansion in the mid-20th century.[2] This connectivity supports daily commutes for millions, alleviating pressure on parallel arterials and enabling economic participation in logistics-driven job markets, though peak-hour demands highlight its foundational yet capacity-constrained role in broader mobility networks.[92]Congestion, Costs, and Policy Debates
Interstate 10 in California suffers from chronic congestion, particularly along its 46.8-mile stretch from Santa Monica through downtown Los Angeles to the eastern suburbs, where it ranks as Southern California's worst freeway according to a 2025 Los Angeles Times analysis based on average speeds, delays, and other metrics.[93] Average speeds on this segment fall to 52 mph, the slowest among major regional freeways, with peak-hour delays often exceeding 45 minutes even on routine commutes.[94] These bottlenecks stem from high vehicle volumes—exceeding 300,000 daily on core sections—combined with merges at interchanges like I-405 and I-110, exacerbating slowdowns during morning (7-10 a.m.) and evening (4-7 p.m.) rush hours.[95] The economic toll of I-10 congestion contributes significantly to the broader Los Angeles metropolitan area's losses, estimated at $13.3 billion annually in 2014 from wasted time, excess fuel consumption, and reduced productivity, with freight trucking alone facing nationwide delays costing $108.8 billion in 2022 due to similar urban chokepoints.[96][97] INRIX data for 2024 indicates U.S. drivers lose an average of 42 hours yearly to gridlock at a cost of $733 per driver, but Los Angeles-area figures are substantially higher, with I-10's role as a primary freight corridor amplifying impacts on goods movement and supply chains.[98] Maintenance and vehicle wear from stop-and-go traffic further inflate costs, as idling and braking accelerate depreciation in a region where I-10 handles over 10% of California's interstate truck traffic.[99] Policy debates over addressing I-10's issues revolve around capacity expansion versus demand management and land-use reforms, with Caltrans advocating projects like corridor widenings and express lanes to add lanes and improve flow, as seen in approvals for doubling segments from four to eight lanes.[100] Proponents cite empirical evidence that targeted highway additions reduce delays without proportional induced demand when paired with regional growth controls, potentially yielding billions in time savings for Los Angeles-area users.[101] Critics, including advocacy groups like Transform, contend expansions exacerbate sprawl and emissions while ignoring root causes such as housing shortages and inadequate transit, arguing instead for density increases and alternatives despite data showing transit's limited mode share (under 5% for LA commutes).[102] Internal Caltrans tensions, including the 2023 demotion of an official opposing expansions, highlight divisions over environmental reviews under CEQA, which delay projects and favor non-road solutions amid rising funding pressures from gas taxes and federal grants.[103][104] These disputes persist as post-2023 fire reconstructions incorporate resilience but face scrutiny over long-term efficacy without broader supply-side interventions.[105]Future Plans
Current and Proposed Projects
In San Bernardino County, the Interstate 10 Corridor Project, Contract 1, is widening the freeway by adding one mixed-flow lane in each direction over approximately 10 miles from the Los Angeles-San Bernardino county line to Interstate 15, with construction advancing to improve capacity and reliability.[58] Concurrently, the San Bernardino Associated Governments (SBCTA) completed the I-10 Truck Climbing Lane project in August 2025, which added a dedicated lane near the San Bernardino Mountains to reduce truck-related accidents and enhance safety on steep grades.[26] The SBCTA is advancing Phase II of the I-10 Express Lanes, planning to add 11.1 miles of tolled lanes from Interstate 15 to Pepper Avenue in Colton, building on existing express infrastructure to manage congestion through dynamic pricing.[14] Further east, the broader I-10 Corridor Project proposes extending express lanes across a 33-mile segment from Montclair to Redlands, incorporating tolling to fund improvements and prioritize high-occupancy vehicles.[6] In Riverside County, the Riverside County Transportation Commission (RCTC) is developing the I-10 Highland Springs Interchange project to reconfigure lanes, add auxiliary merging lanes, and enhance ramps, addressing high traffic volumes and safety issues at this key junction.[106] The Da Vall Drive/I-10 Interchange project is also underway, focusing on capacity upgrades to support regional growth.[29] Additionally, Phase II of the I-10/Riverside Avenue Freight Improvement Project in Rialto aims to expand freight throughput along this urban corridor, reducing bottlenecks for commercial traffic.[107] Los Angeles County efforts include the Metro I-10 ExpressLanes Extension Project, which proposes options such as converting high-occupancy vehicle lanes to high-occupancy toll lanes or adding a second express lane per direction between Interstate 605 and the county line, targeting peak-hour relief on this high-volume route.[35] The I-10 Multimodal Corridor Plan by Caltrans seeks to integrate bus rapid transit, active transportation, and rail extensions like the D Line from Santa Monica to downtown Los Angeles, emphasizing reduced emissions and equitable access over the next decade.[108] Local initiatives, such as the I-10/Robertson/National Area Circulation Improvement Project in Culver City, are redesigning ramps and intersections for multimodal safety.[109] Proposed interchanges include the Wildwood Canyon Road project in Yucaipa, which would construct a full diamond interchange to alleviate congestion and bolster economic access in eastern San Bernardino County.[110] These initiatives, largely funded through state and federal programs like the State Transportation Improvement Program, face scrutiny over costs and environmental impacts but aim to address persistent overload on I-10, which carries over 300,000 vehicles daily in urban segments.[111]Long-Term Expansion Proposals
Long-term expansion proposals for Interstate 10 in California emphasize the addition and extension of managed (express) lanes rather than traditional general-purpose lane widening, driven by projections of substantial traffic increases and state policies prioritizing congestion pricing, high-occupancy toll (HOT) operations, and integration with transit options. The Southern California Association of Governments' Connect SoCal 2024 Regional Transportation Plan, covering through 2045, identifies I-10 corridor enhancements as key to accommodating regional growth, with managed lanes expected to handle up to 20-30% more throughput via dynamic tolling without requiring excessive right-of-way acquisition.[112][113] These approaches aim to improve reliability for freight and commuters, as I-10 serves as a primary east-west artery for goods movement from ports to inland distribution centers, where daily volumes could reach 350,000 vehicles by 2045 under baseline growth scenarios.[11] In the Los Angeles County segment, the I-10 ExpressLanes Extension Project proposes adding two HOT lanes in each direction from Interstate 605 to the Los Angeles-San Bernardino county line, approximately 7 miles, to connect seamlessly with existing facilities and mitigate spillover congestion. A draft Environmental Impact Report is slated for 2026, with construction targeted to start in 2029, funded partly through federal grants and local measures like Metro's sales tax programs; this would elevate peak-hour speeds from current averages below 40 mph to over 60 mph in managed lanes, based on modeling from similar implementations.[35] Critics from transportation advocacy groups argue that without complementary transit expansions, such as bus rapid transit feeders, these lanes may primarily benefit solo drivers able and willing to pay tolls, potentially exacerbating equity issues in low-income corridors.[114] Eastward in San Bernardino and Riverside counties, the San Bernardino Associated Governments (SBCTA) envisions extending express lanes from the county line through Redlands to as far as Yucaipa, spanning over 20 miles, as part of the I-10 Corridor Project's phased rollout under Measure I funding reauthorization. This includes bridge widenings, auxiliary lane additions, and interchange upgrades at locations like Cedar Avenue and Wildwood Canyon Road to support truck access and future volumes projected to double local freight traffic by 2040.[115][116] The Riverside County Transportation Commission's Inland Empire Comprehensive Multimodal Corridor Plan outlines complementary widening of the I-10/Riverside Avenue interchange and potential HOT lane conversions to handle spillover from SR-60 merges, with environmental clearances pending through 2027.[117] These proposals align with Caltrans' California Transportation Plan 2050, which advocates zero-emission vehicle incentives alongside capacity tweaks over new alignments, though empirical data from existing express lanes shows peak reductions of 15-20% only when enforcement and pricing are optimized.[118] Funding challenges persist, relying on volatile gas taxes and toll revenues, with no firm commitments for full corridor conversion before 2035.[119]Exit List
Los Angeles County Exits
Interstate 10 enters Los Angeles County at its western end in Santa Monica, where postmile 0.00 marks the beginning, and proceeds eastward through densely urbanized areas including West Los Angeles, Downtown Los Angeles, and the San Gabriel Valley before crossing into San Bernardino County near the Pomona city line at approximately postmile 47.5.[19] Exit numbering follows the California Numbered Exit Uniform System (Cal-NExUS), aligning with postmiles for consistency across the state, with installations ongoing as of the 2020 documentation.[19] The route features complex interchanges with other freeways such as I-405, I-110, I-5, I-710, and I-605, serving high-traffic corridors for regional commuting and freight movement. The following table enumerates all exits in Los Angeles County from west to east, including postmiles, exit numbers (installed or proposed under Cal-NExUS), and primary destinations. Some early exits share alignments or lack dedicated signage at the time of documentation.| Postmile | Exit | Destinations |
|---|---|---|
| 0.00 | 1A | 4th Street, 5th Street (shared with SR 1)[19] |
| 0.96 | 1C | 20th Street, Lincoln Boulevard[19] |
| 2.08 | 2A | Centinela Avenue[19] |
| 2.30–2.35 | 2B–2C | Bundy Drive[19] |
| 3.11–3.29 | — | I-405 (to Sacramento, LAX Airport, Long Beach)[19] |
| 4.24–5.05 | 5 | National Boulevard, Overland Avenue[19] |
| 5.76–9.23 | — | Robertson Boulevard; La Cienega Boulevard, Venice Boulevard, Fairfax Avenue, Washington Boulevard; La Brea Avenue; Crenshaw Boulevard[19] |
| 10.16–11.64 | — | Arlington Avenue; Western Avenue, Normandie Avenue; Hoover Street, Vermont Avenue[19] |
| 12.68–12.73 | 13A–13B | I-110 / Harbor Freeway (to San Pedro, Pasadena)[19] |
| 13.64–15.55 | 14A–15A | Maple Avenue, East 18th Street; San Pedro Street; Central Avenue; Alameda Street; Santa Fe Avenue, Mateo Street[19] |
| 16.23 | — | SR 60 East, I-5 (to Pomona, Santa Ana, Sacramento)[19] |
| 19.07–19.59 | 19A–19C, 20A | State Street, US 101 North, Soto Street (left exits); City Terrace Drive[19] |
| 20.24–20.77 | 20B | Eastern Avenue; I-710 / Long Beach Freeway[19] |
| 21.70–26.25 | — | Fremont Avenue; Atlantic Boulevard; Garfield Avenue; New Avenue, Del Mar Avenue; San Gabriel Boulevard; Walnut Grove Avenue[19] |
| 27.35–28.94 | — | SR 19 / Rosemead Boulevard; Santa Anita Avenue; Peck Road, Valley Boulevard[19] |
| 29.97 | 30 | Garvey Avenue, Durfee Avenue[19] |
| 30.54 | — | I-605[19] |
| 30.93–32.05 | 31C | Frazier Street; Baldwin Park Boulevard; Francisquito Avenue[19] |
San Bernardino County Exits
Interstate 10 enters San Bernardino County at post mile 47.66 near the Los Angeles county line and exits at post mile 86.82 near the Riverside county line, passing through cities such as Rancho Cucamonga, Fontana, Rialto, Colton, and San Bernardino.[19] The segment features interchanges with major routes including Interstate 15 and State Route 210, serving industrial, residential, and commercial areas.[19] Exits follow the California Numbered Exit Uniform System, based on mileposts from the route's western terminus.[19]
| Exit | Post Mile | Destinations | Notes |
|---|---|---|---|
| 48 | 48.34 | Monte Vista Avenue | |
| 49 | 48.89 | Central Avenue | |
| 50 | 50.03 | Mountain Avenue / Mt Baldy | |
| 51 | 51.13 | SR-83 / Euclid Avenue | |
| 53 | 53.76 | Vineyard Avenue | |
| 55 | 54.82 | Holt Blvd / Archibald Avenue | |
| 56 | 55.83 | Haven Avenue | |
| 57 | 56.84 | Milliken Avenue | |
| 58A | 57.60 | I-15 North / Barstow / Las Vegas | |
| 58B | 57.60 | I-15 South / San Diego | |
| 59 | 58.79 | Valley Blvd / Etiwanda Avenue | |
| 61 | 60.83 | Cherry Avenue | |
| 63 | 62.84 | Citrus Avenue | |
| 64 | 63.88 | Sierra Avenue / Fontana | |
| 66 | 66.15 | Cedar Avenue / Bloomington | |
| 68 | 67.63 | Riverside Avenue / Rialto | |
| 69 | 68.63 | Pepper Avenue | |
| 70 | 69.62 | Rancho Avenue | |
| 71 | 70.91 | Mt Vernon Ave | |
| 73 | 72.92 | Waterman Avenue North | Proposed as 73B |
| 74 | 73.93 | Tippecanoe Avenue / Anderson St | |
| 75 | 74.96 | Mountain View Avenue / Loma Linda | |
| 76 | 75.96 | California Street | |
| 77A | 76.97 | Alabama Street | |
| 77B | 77.29 | SR-210 / Highland / SR-330 / Big Bear | |
| 78 | 78.56 | SR-38 / Eureka St / Orange Street | |
| 79 | 79.53 | University Street | |
| 80 | 80.79 | Ford Street | |
| 81 | 81.95 | Wabash Avenue | |
| 82 | 83.16 | Yucaipa Blvd | |
| 83 | 84.69 | Oak Glen Rd / Live Oak Canyon Road | |
| 86 | 86.82 | Rest Area | At county line |
Riverside County Exits
Interstate 10 enters Riverside County at the San Bernardino county line near Calimesa, at county postmile R 0.00 corresponding to statewide milepost 86.82. The freeway spans approximately 156 miles through the county, transitioning from foothill communities like Beaumont and Banning, through the Coachella Valley including Palm Springs, Cathedral City, Palm Desert, and Indio, and into remote desert terrain toward Blythe before crossing into Arizona at statewide milepost 243.31.[19] Exit numbering follows California's uniform system, based on cumulative mileage from the route's western terminus near Santa Monica, with numbers increasing eastward.[19] The following table lists all exits in Riverside County, including exit numbers, approximate statewide mileposts, and primary destinations (noting eastbound/westbound differences where applicable). Data reflect the configuration as of the latest Caltrans documentation.[19]| Exit | State Mile | Destinations |
|---|---|---|
| 87 | 86.84 | County Line Road |
| 88 | 87.68 | Calimesa Boulevard |
| 89 | 88.74 | Singleton Road |
| 90 | 89.87 | Tuckwet Canyon Parkway (EB); Cherry Valley Road (WB) |
| 91 | 90.88 | Rest Area |
| 92 | 92.35 | Oak Valley Parkway |
| 93 | 93.49 | SR 60 West / Riverside (left exit) |
| 94 | 94.39 | SR 79 South / Beaumont Avenue |
| 95 | 95.03 | Pennsylvania Avenue |
| 96 | 96.13 | Highland Springs Avenue |
| 98 | 98.15 | Sunset Avenue |
| 99 | 98.78 | 22nd Street |
| 100 | 99.67 | SR 243 South / 8th Street |
| 101 | 100.68 | Hargrave Street; Idyllwild (WB) |
| 102 | 101.58 | Ramsey Street |
| 103 | 103.36 | Malki Road |
| 104 | 104.48 | Morongo Trail |
| 106 | 106.22 | Main Street (Banning) |
| 110 | 111.37 | Haugen-Lehmann Way |
| 111 | 112.02 | SR 111 / Palm Springs |
| — | 113.07 | Rest Area |
| 114 | 114.05 | Whitewater |
| 117 | 116.51 | SR 62 North / Twentynine Palms |
| 120 | 119.95 | Indian Canyon Drive |
| 123 | 122.96 | Palm Drive / Gene Autry Trail |
| 126 | 126.31 | Date Palm Drive; Vista Chino Road (WB) |
| 130 | 130.18 | Bob Hope Drive |
| 131 | 131.33 | Monterey Avenue |
| 134 | 133.71 | Cook Street |
| 137 | 137.27 | Washington Street; Country Club Drive (WB) |
| 139 | 139.16 | Jefferson Street / Indio Boulevard (WB) |
| 142 | 141.56 | Monroe Street |
| 143 | 142.56 | Jackson Street |
| 144 | 143.77 | Golf Center Parkway |
| 145 | 144.65 | SR 86 / Brawley / El Centro |
| 146 | 145.71 | Dillon Road; SR 86 / Coachella (WB) |
| — | 158.82 | Rest Area |
| 162 | 161.94 | Frontage Road |
| 168 | 168.37 | Mecca / Twentynine Palms |
| 173 | 172.89 | Chiriaco Summit |
| 177 | 176.94 | Hayfield Road |
| 182 | 181.87 | Red Cloud Road |
| 189 | 188.83 | Eagle Mountain Road |
| 192 | 191.92 | SR 177 North / Desert Center |
| 201 | 201.22 | Corn Springs Road |
| 217 | 216.76 | Ford Dry Lake Road |
| 222 | 221.87 | Wiley's Well Road / Rest Area |
| 230 | 229.44 | Weigh Station |
| 232 | 231.94 | Airport / Mesa Drive |
| 236 | 235.97 | SR 78 South / Neighbors Boulevard |
| 239 | 238.97 | Lovekin Boulevard / Blythe |
| 240 | 239.98 | 7th Street / Blythe (WB) |
| 241 | 240.99 | US 95 North / Intake Boulevard |
| 243 | 242.92 | Riviera Drive |