Skip to main content

November Bay Trip Part 2; Mount Diablo State Park

The Diablo Range is a long inland Californian Coastal range stretching from the Carquinez Straight near San Francisco Bay south to the Temblor Range roughly bounded by California State Route 46. I've been down pretty much almost every major road in the Diablo Range over the years, some are among my favorites like CA 198 and the Parkfield Grade.  There has been two major roads I had left to explore in the Diablo Range that I've been meaning to get off my list of things to do.  First is Idria Road to the Idria Mine and the Summit Road of Mount Diablo in Mount Diablo State Park.






After jumping onto I-580 after completing I-205 I took I-680 north to Diablo Road.





I took Diablo Road to Mount Diablo Scenic Boulevard which runs to the southern entrance of the State Park becoming South Gate Road.







Mount Diablo is a 3,849 peak in the northern Diablo Range.  While not the tallest peak in the Diablo Range Mount Diablo has a prominence of 3,109 feet which gives it one of the widest vistas in all of California.  Mount Diablo is the tall mountain that can be seen east of the Golden Gate Bridge behind San Francisco Bay and Oakland.

Mount Diablo is accessed via the Summit Road which is reached by the South Gate Road from the south and the North Gate Road from the north.  The South Gate Route is 10.5 miles from the state park entrance and averages a 5.8% grade on a 3,169 foot ascent.  The North Gate Road route is 12.4 miles long from the state park entrance and averages a 6% grade on a 3,687 foot ascent.  The vital statistics I just cited were obtained from Pjammey Cycling which is probably the best place to get grade information on notable Californian roadways.  The link below even has a handy map of both the South and North Gate Roads.

Pjammey Cycling on Mount Diablo

Given I just cited a cycling website you'd might imagine the road is popular for cyclists and you'd certainly be correct about that.  Signage warns drivers constantly to be leery of Cyclists.  My ascent to Mount Diablo was on the South Gate Road while my descent was on the North Gate Road.





The 1,000 foot line is reached quickly on the South Gate Road.





The South Gate Road has a ton of open vistas along sweeping cliff-side roadways that utilize numerous hairpins.


The actual gate on South Gate Road is actually several miles into Mount Diablo State Park.


Mount Diablo finally starts to come into view, the Summit Road really does go all the way to the top.





The South and North Gate Roads meet at the Walnut Creek Ranger Station which is about 2,000 feet above sea level.


The Summit Road is only 4.3 miles long but gains the bulk of the elevation up to Mount Diablo.  Apparently the average grade on the Summit Road is 6.7% but there is definitely a spot or two near the top over 10%.





The drive to the top of the Summit Road isn't fast with 15-20 MPH speed limits but it is plenty wide and well engineered.  I wasn't hurting for passing room for bikes or oncoming traffic on the ascent up to the summit.









The actual top of Summit Road is the actual 3,849 peak of Mount Diablo.


There is one hell of a view looking back south at all the switchbacks along Summit Road.  It reminds me of a miniature Pikes Peak Highway.






The views of the area were kind of obstructed eastward with a cloud hanging over the summit.






Part of Mount Diablo was acquired for State Park use in 1921 but it wasn't until 1931 that enough land was annexed before the park was formally dedicated.  The Summit Building was built sometime in the 1930s.





The drive back down to the Walnut Creek Ranger Station is stunning.  I used 1st gear most of the way down off the Summit Road given the speed limit was so low that I didn't feel a need to use my brakes up.












The North Gate Road is far less daunting than the South Gate Road.  There are a couple hairpins but they are far wider than the South Gate Road.  There was some minor road damage along the North Gate Road but nothing too out of control.  Unlike the South Gate Road the actual gate is at the state park boundary.











According to the Mount Diablo State Park brochure North Gate, South Gate, and Summit Road were all opened as stage routes in 1874.  Apparently the roads were closed sometime in the 1890s and reopened again by 1915.

Mount Diablo State Park Brochure

All three roads are clearly seen on the 1935 California Division of Highways map Contra Costa County as under county maintenance.

1935 Contra Costa County Map






 

Comments

Popular posts from this blog

Hetch Hetchy Valley; Hetch Hetchy Railroad, abandoned Lake Eleanor Road, and the Wapama Fall Bridge

This June I took a trip out to Yosemite National Park upon receiving my COVID-19 Day Use Reservation.  My destination in Yosemite National Park was out in Hetch Hetchy Valley.  I sought to hike to the Wapama Fall Bridge which took me through some of the path of the former Hetch Hetchy Valley Railroad and abandoned Lake Eleanor Road.



Part 1; Hetch Hetchy Valley, the Hetch Hetchy Railroad, and reservoir roads

Hetch Hetchy is glacially carved valley similar to Yosemite Valley which is located on the Tuolumne River of Tuolumne County.  Hetch Hetchy Valley presently is impounded by the O'Shaughnessy Dam which was completed during 1923 as part of a project to deliver water and hydroelectric power to the City of San Francisco.  Before being impounded Hetch Hetchy Valley had an average depth of approximately 1,800 feet with a maximum depth of approximately 3,000 feet.  Hetch Hetchy Valley is approximately three miles long and as much as a half mile wide.  Hetch Hetchy Valley is located dow…

Mineral King Road, the White Chief Mine, and the unbuilt California State Route 276

Back in July of 2016 I took Mineral King Road east from California State Route 198 to Mineral King Valley within the Sierra Nevada Mountains of Sequoia National Park.  This June I revisited Mineral King Valley and made my way up to the White Chief Mine.


Mineral King Road is a 24.8 mile rural highway maintained by the National Park Service and as Tulare County Mountain Road 375.  Mineral King Road originates at California State Route 198 in Three Rivers near the confluence of the Middle Fork Kaweah River and the East Fork Kaweah River.  Mineral King Road climbs from a starting elevation of 1,400 feet above sea level to 7,830 feet above sea level at the White Chief Mine Trailhead in Mineral King Valley.  Notably Mineral King Road is stated to have 697 curves.


Mineral King Road has an average grade of 5.1% but has several stretches between 15-20% in places.  Pjammycycling has a detailed breakdown on the grade levels over the entirety of Mineral King Road.

Pjammycycling on Mineral King R…

California's Rogue Sign State Route Shields

While recently revisiting Yosemite National Park I took a couple minutes to capture some of the California Sign State Route shields posted by the National Park Service ("NPS").  None of the NPS shields were actually posted on roadways maintained by Caltrans but were clearly intended to create route continuity with the Sign State Highways.  This phenomenon is not exclusive to Yosemite National Park and can be found on numerous roads not maintained by Caltrans throughout California.



Part 1; Route continuity over who maintains the route

In the very early era of State Highways in California the Division of Highways didn't actually field sign the Auto Trails or even US Routes.  The responsibility of Highway signage fell to the California State Automobile Association ("CSAA") and Automobile Club of Southern California ("ACSC").  The Auto Clubs simply signed Highways on roadways that best served navigational purposes.  These navigational purposes often didn&#…