page_title: Dumbarton Bridge (California)
section_title: History and engineering features
hierarchical_section_title: Dumbarton Bridge (California) / History and engineering features
caption_attribution_description: English: The original vertical-lift Dumbarton Bridge is shown alongside its replacement span, shortly before the demolition of the older bridge in September 1984. The bridge is the southernmost crossing of the San Francisco Bay.
context_page_description: The Dumbarton Bridge is the southernmost of the highway bridges across San Francisco Bay in California. Carrying over 70,000 vehicles and about 118 pedestrian and bicycle crossings daily, it is the shortest bridge across San Francisco Bay at 1.63 miles. Its eastern end is in Fremont, near Newark in the San Francisco Bay National Wildlife Refuge, and its western end is in Menlo Park. Bridging State Route 84 across the bay, it has three lanes each way and a separated bike/pedestrian lane along its south side. Like the San Mateo Bridge to the north, power lines parallel the bridge.
context_section_description: The bridge has never been officially named, but its commonly used name comes from Dumbarton Point, named in 1876 after Dumbarton, Scotland. Built originally to provide a shortcut for traffic originating in San Mateo and Santa Clara counties, the bridge served industrial and residential areas on both sides. The earlier bridge opened on January 17, 1927, and was the first vehicular bridge to cross San Francisco Bay. A portion of this old drawbridge remains as a fishing pier on the east side of the Bay. The original bridge was built with private capital and then purchased by the state for $2.5 million in 1951.
  Its age and the two-lane undivided roadway and lift-span led to a replacement bridge being built to the north. This bridge opened in October 1982 as a four-lane, high-level structure. The structure was re-striped to accommodate six lanes on October 18, 1989, in response to the temporary closing of the San Francisco–Oakland Bay Bridge due to the Loma Prieta earthquake, and the permanent widening of the approaches was completed by July 2003. The cost of the complete replacement project was $200 million. The current bridge includes a two-way bicycle and separate pedestrian path on the south-facing side. A 340 ft (104 m) center span provides 85 ft (26 m) of vertical clearance for shipping. The approach spans on both sides of the Bay are of pre-stressed lightweight concrete girders supporting a lightweight concrete deck. The center spans are twin steel trapezoidal girders which also support a lightweight concrete deck.
  The center span of the original bridge was demolished in a controlled explosion in September 1984.
caption: The original vertical-lift span of the Dumbarton Bridge, shown in 1984 shortly before it was demolished
exif: {"Image ImageDescription": "After the new Dumbarton Bridge was opened for traffic, part of the original structure had to be demolished. This process began in September 1984, using explosives to obliterate the vertical-lift drawbridge.", "Image Orientation": "Horizontal (normal)", "Image XResolution": "400", "Image YResolution": "400", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS2 Macintosh", "Image DateTime": "2008:09:30 15:03:18", "Image ExifOffset": "384", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "522", "Thumbnail JPEGInterchangeFormatLength": "0", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "3886", "EXIF ExifImageLength": "2498"}