MacArthur Maze
The MacArthur Maze (or simply the Maze, also called the Distribution Structure) refers to the large freeway interchange located near the eastern end of the San Francisco ”“ Oakland Bay Bridge in Oakland, California. Principally it can be seen as splitting Bay Bridge traffic into three freeways, the Eastshore, MacArthur and Nimitz, although other movements are important.

Because of its central location within the San Francisco Bay Area and the funneling of traffic arising from the limited number of bridges spanning the bay, the Maze has become a major hub for both east”“west and north”“south traffic in the Bay Area. The Maze is a major corridor for commuters living in the East Bay and working in San Francisco. The Maze is immediately adjacent to both the Port of Oakland, which is the fourth busiest container port in the United States, and to downtown Oakland. Two major interstate freeways from outside of the Bay Area region, I-80 and I-5 (via either I-80 or I-580) connect to the Maze. All of these factors generate substantial traffic.

Freeways connecting in the Maze
  • The Bay Bridge - Interstate 80 from the Maze heads west across the Bay Bridge into San Francisco.
  • The Eastshore Freeway - The Interstate 80/Interstate 580 concurrency from the Maze heads north through Berkeley and western Contra Costa County. Just north of the Berkeley-Albany border, approximately 4 miles (6.4 km) north of the Maze, the concurrency splits, with Interstate 80 heading north, then northeast towards Sacramento and Interstate 580 heading northwest towards the Richmond-San Rafael Bridge and eventually to Marin County, where it joins U.S. 101.
  • The MacArthur Freeway - Interstate 580 from the Maze heads southeast through Oakland. About a mile southeast is an interchange with State Route 24/ Interstate 980, a major corridor for commuters living in Contra Costa County. I-580 continues southeast along the foot of the hills (and nearly atop the trace of the Hayward Fault) to Castro Valley, where the route turns east and becomes the Castro Valley Freeway (continuing through the Livermore Valley, over Altamont Pass and eventually ending up near Tracy where it joins with Interstate 5).
  • The Nimitz Freeway - Interstate 880 from the Maze heads south and southeast through Oakland along the Oakland Estuary, past the Oakland International Airport, and McAfee Coliseum, then through southern Alameda County and eventually to San Jose, where it turns into Highway 17 and heads to Santa Cruz where it ends.


The Maze was built as part of the construction of the Bay Bridge in the 1930s. It was technically named the "Distribution Structure", but owing to its size and complexity, was very early given the name "Maze" by the media and public. The first maze was smaller in scale than today's interchange, but was still impressive for its time. It was built to handle motor vehicle traffic east and west bound across the Bay Bridge along with north and south bound automobile traffic in the East Bay. There were three principal feeder routes utilizing ramps: a viaduct from the end of Cypress Street (State Highway 17) in Oakland; a viaduct from the end of 38th Street (U.S. Route 50; 38th was subsequently renamed "MacArthur Boulevard") at San Pablo Avenue in Oakland; and the Eastshore Highway which carried U.S. Route 40 along the shoreline of Albany, Berkeley, and Emeryville. The Maze was significantly re-engineered and enlarged in the mid-1950s in association with the original construction of the three freeways which converge there today. Following the Loma Prieta Earthquake, another round of extensive re-engineering was undertaken, including the addition of special diamond lane ramps and a huge girder flyover connecting the relocated northbound Nimitz with the northbound Eastshore Freeway (which is technically I-80 eastbound and I-580 westbound). The extended nickname "MacArthur" Maze originated sometime after the construction of the MacArthur Freeway in the late 1950s (named after General Douglas MacArthur.) Historic film footage of the early Maze can be seen in the 1941 movie Shadow of the Thin Man , as Nick and Nora Charles drive off the Bay Bridge on their way to Golden Gate Fields in Albany.

Effects of the 1989 Loma Prieta earthquake
During the October 17, 1989, Loma Prieta earthquake, which measured 7.1 M w , the double-decked Cypress Street Viaduct on I-880 between I-80 and the 14th Street exit collapsed, crushing cars and killing 42 people. Traffic on the MacArthur Maze headed towards I-880 was re-routed to I-580 and I-980, and ramps at both ends of the viaduct leading to the former Cypress Structure were signed for local traffic access to Cypress Street. The Cypress Street Viaduct was demolished soon after the earthquake, but a replacement freeway was not substantially completed until July 1997, due to lawsuits by environmentalists and local residents. The final connection to the Maze, known as the East Bay Viaduct, was not opened until 1998 (though a separate connection running northwest to the Bay Bridge along the alignment of the old Grand Avenue Viaduct was built in 1995). The replacement sections of the Nimitz Freeway dispensed with the double-deck design. It was constructed near the Union Pacific railway tracks around the outskirts of West Oakland, rather than bisecting that neighborhood as the old Cypress Viaduct did. Cypress Street, which ran in the shadows on either side of the old double-decked structure, is now a landscaped parkway along its entire length, and has been renamed as Mandela Parkway. In 2007, Mandela Parkway was linked at its northern end with the western end of Yerba Buena Avenue, creating a through route into Emeryville.

2007 I-580 East Connector Collapse
At 3:42 am on the morning of Sunday, April 29, 2007, a tank truck carrying 8,600 gallons (32,500 liters) of unleaded gasoline overturned on the connector from Interstate 80 west (from Berkeley) to Interstate 880 south. Wikimapia The intense heat from the subsequent fuel spill and fire weakened the steel structure of the roadway above, which served as the connecting ramp from Interstate 80 east (from San Francisco) to Interstate 580 east (to Oakland), collapsing approximately 168 feet (50 m) of it onto the lower connector. The truck driver involved suffered second degree burns on his hands but was nonetheless able to walk 1.5 miles (2.4 km) to a gas station, where he found a taxi and was given a ride to Oakland Kaiser Medical Center. No other vehicles or persons were reported to be involved in the accident. The California Highway Patrol (CHP) initially reported that they suspect that the tanker had been speeding and bounced off a guard rail leading to the overturn. The driver was found to have a clean record the preceding decade; drug or alcohol use was determined not to be a factor in this accident. The collapse of this bridge cut off the return route from San Francisco for many East Bay commuters (primarily those whose destinations are Walnut Creek and southeastern Oakland). To help ease the expected traffic snarl, Caltrans set up temporary detours within the days following the incident, Bay Area Rapid Transit (BART) added additional capacity to lines serving areas that had been impacted by the incident, and on Monday April 30, all public transportation in the Bay Area was free, with the estimated cost of $2.5 million paid out of state funds. News commentators have pointed out the similarities to the disruption caused by the Loma Prieta earthquake 18 years earlier. Fortunately as of May 3, 2007 while there was some serious congestion on the detour routes, the expected traffic jams and long delays had yet to fully materialize. This was possibly caused by commuters switching to alternate transit options indicated by BART posting record ridership numbers as of that date. Rebuilding Caltrans spokespersons estimated immediately after the accident that it would take weeks to clear the debris from the scene and months to rebuild the affected sections. Initial cost projections for rebuilding the 580 connector alone reached $10 million. However, due to the urgency to reopen such a vital highway link the project was expedited, and most demolition work and debris removal was completed by the Tuesday following the accident. For a historic comparison, Caltrans did successfully replace a single damaged upper deck panel of the Bay Bridge (after the Loma Prieta earthquake) and the collapsed portion of the I-10 Santa Monica Freeway in Los Angeles (after the Northridge Earthquake) in roughly one month by expediting its internal approval process and offering an incentive program for the contractors. On May 7, 2007, the I-880 connector reopened at 4:30 am to traffic. Substantial work was done to retrofit the structure for strength, which sank 9 inches (230 mm) due to the collapse of the I-580 connector onto the I-880 connector. A contractor with a proven track record of rebuilding damaged freeways (most notably the Santa Monica Freeway after the 1994 Northridge Earthquake) well ahead of schedule, C. C. Myers, Inc., submitted a winning bid of $876,075 to repair the damage to the I-580 connector. The bid was estimated to cover only one-third of the cost of the work, but the firm counted on making up the shortfall with an incentive of $200,000 per day if the work was completed before June 27, 2007. On the evening of Thursday, May 24, the I-580 connector re-opened, just before the busy Memorial Day weekend. The deadline to finish the project was beaten by over a month, with the contractor earning the $5 million bonus for early completion. The entire reconstruction project was completed only 26 days after the original accident. A state projection concluded that the connector collapse had cost $90 million, based on a $6 million per day economic impact estimate. This includes a $491,000 loss in toll revenue for the Oakland Bay Bridge. On May 25, 2007, the CHP revoked the license for transporting hazardous materials from Sabek Transportation, the owner of the tank truck, after an investigation found 36 violations of its operations and equipment.