Road Scholar tutorial

Over the years I’ve ridden my bike on every kind of surface imaginable. Nothing beats a new coat of asphalt.

My fondest memory of a newly paved road is Hwy 236 through Big Basin Redwoods State Park.

That’s because the old road was badly broken when repaved in 2016, so the new road felt like heaven.

Here are the main types of road construction methods:

Dirt – Needs no explanation. Without maintenance, dirt roads degrade faster than any other surface. They can be muddy in the wet, and dusty when dry.

Alpine Road in 1990 after grading.

Gravel – Nothing more than a dirt road with a layer of gravel. Thick gravel is bad news for bikes. Gravel reduces erosion and improves traction in wet, versus mud.

Gravel road at Col de Tende in 1986. It’s still unpaved
on the French side.

Roman, Stone, Brick – I categorize these types as one. Roman roads are renowned for lasting millennia, although not without maintenance. Bumpy as hell. Think Paris-Roubaix.

Roman road near Naples.
Brick road in Switzerland.

Macadam – Named after John McAdam, a Scottish road builder. It’s basically different sizes of gravel, finest grade at the top. McAdam added compression to make the road last longer. Heavy cast-iron rollers were used to compress gravel, sand, and rock beginning in the 1800s. The U.S. completed its first macadam road in 1830 in Maryland, the Boonsborough Turnpike.

I know macadam roads were built in the Bay Area, but I’m not sure if there are any today.

You might say the improved Bay Trail between Santa Clara and Mountain View is a macadam road, using gravel and fine-grain sand. It’s well compacted and resists water better than any dirt or gravel road.

Tarmac – This is an early form of pavement, patented by Edgar Hooley in 1902, but McAdam made a similar material in the 1830s. Tar is mixed with gravel. It wasn’t used widely until the advent of the automobile.

I suppose some the old Bay Area’s roads paved today started as tarmac. I associate tarmac with chunky gravel. You see it on many old roads around here that have been abandoned.

Tarmac on Montebello Road.

Asphalt – It’s the most popular road surface in the world. Modern petrochemicals are mixed with sand, rubber, and all sorts of other materials, such as glass, to create a smooth surface. It dates back to 1870, with improvements in 1900 and 1907, when refined petroleum was used — modern asphalt.

Concrete – This material was all the rage for road building starting in the 1920s. It’s still popular today. It consists of Portland cement (clay and limestone binding agent), sand, and water, which hardens into concrete.

One of the best examples of a concrete road, about 100 years old and still in use, is Old Santa Cruz Highway.

Old Santa Cruz Hwy south of Summit Road.

5 Responses to “Road Scholar tutorial”

  1. jamesRides Says:

    Midpen is using something I’ll just call “hardpack” on many of their highly trafficked trails. The classic example is Montebello Road/trail at the very top of black mountain on the south side. Typically this section of the trail was heavily rutted by yearly rains. They installed the hardpark about 3 years ago. It is now beginning to erode but the the section is still very rideable on road bike. The hardpack seems to be a mixture of pebble gravel with a cement binder, maybe an inch thick. It isn’t pure gravel and it isn’t concrete – something in between. I think they also roll it when they can. It’s now in use in Rancho San Antonio on PGE trail, and Montebello White Oak.

    I think you also wrote about west highway 9. With the recent resurface it is smooth as silk. Mountain Charley out of Scotts Valley – worst road to ride down but fun to ride up due to the surface. Wonder what that is made from?

    • Ray Hosler Says:

      Now that you mention it, probably the same process used on the Bay Trail. It looks like dirt, but way harder.

  2. Robert Neff Says:

    Los Gatos and Palo Alto both have concrete streets.

  3. Ted Pauly Says:

    Good stuff thanks!! Ride bike

    Sent from my iPhone


  4. Jack Says:

    There are some wonderful old logging roads in Southern Oregon with mostly gentle grades that you can ride on for hours without seeing a car. When I was up there, I was reminded of some of the Once Upon a Ride reports, and how I wish I had been born a couple decades earlier! Thanks for this post, BTW. Very informative.

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