American Rural Highways Informative Summary

Overview:

“American Rural Highways,” published in 1920, examines the pivotal role of roads in national development, focusing on rural communities. The text emphasizes the vital connection between transportation and agricultural prosperity, arguing that good roads are indispensable for farmers to market their products efficiently, transporting goods and people, and connecting rural communities. The text delves into the complexities of highway administration, highlighting the evolving transition from local to state-level oversight and the growing influence of federal aid.

The text then dives into the specific details of road construction, covering various types like earth roads, sand-clay roads, gravel roads, broken stone roads (macadam), and cement concrete roads, each with its own strengths and limitations. Different construction methods are described, including the use of various machinery like elevating graders, blade graders, wheel scrapers, and road drags. The text also emphasizes the importance of proper drainage, utilizing techniques like side ditches, tile drains, and culverts. Furthermore, it discusses the financial models used to fund road projects, including special assessments, general taxation, vehicle taxes, and bond issues.

Key Findings:

The rise of the motor vehicle revolutionized rural transportation, significantly increasing traffic volume on highways.
Rural highway development is essential for agricultural progress, supporting efficient marketing of farm products and the growth of rural communities.
Highway administration is shifting from local to state-level oversight, with growing federal involvement.
Road construction and maintenance require careful planning and a deep understanding of the soil and climate conditions of the region.
Proper drainage is crucial for ensuring the stability and longevity of any road, regardless of the surface type.

Learning:

Traffic and Transportation: The reader will learn about the diverse types of traffic prevalent on rural highways, including farm-to-market, farm-to-farm, inter-city, and inter-county and inter-state traffic. This understanding helps analyze the unique challenges and needs of different road types.
Highway Administration: The reader gains insights into the different levels of highway administration in the US, including township, county, state, and federal. This helps understand the complexities of policy-making, funding, and implementation.
Road Design and Construction: The reader acquires practical knowledge of the design considerations and construction methods for various road types: earth roads, sand-clay roads, gravel roads, broken stone roads (macadam), and cement concrete roads.
Drainage: The reader learns the importance of proper drainage for all road types and is introduced to various techniques like ditches, tile drains, and culverts.
Road Maintenance: The reader understands the crucial role of maintenance in ensuring the longevity and serviceability of roads, learning about patrol maintenance, gang maintenance, and the specific challenges and methods for maintaining different road types.

Historical Context:

The text was written in 1920, a period of significant change in the US, with the rise of the automobile rapidly transforming transportation and the nation’s infrastructure. The text reflects this changing landscape, acknowledging the growing importance of motor vehicles in rural areas and discussing the need for roads that could accommodate this new type of traffic.

Facts:

Farm Density: The average number of rural families in the United States is between six and eight per square mile, with some areas reaching 20 families per square mile.
Motorized Traffic Dominance: Over 90% of the tonnage transported on rural highways in the US is carried by motor vehicles.
Truck Hauling Costs: The cost of hauling a ton of farm produce ten miles to a railway station is comparable to the cost of hauling it a thousand miles over a trunk-line railway.
Highway Cost: The cost of hauling a ton of merchandise from a freight yard to a merchant’s warehouse in a city is often higher than hauling it over a thousand miles of railway line.
Tractive Resistance: The tractive resistance of a road surface refers to the force needed to move a vehicle over it. It is influenced by factors like tire type, road surface material, and moisture content.
Impact: Impact on a road surface, especially for motor vehicles traveling at high speeds, is a significant factor contributing to wear and tear.
Horsepower and Grade: A team of draft animals weighing 1800 lbs. each can exert a sustained pull of about 360 lbs. and can momentarily exert three times that amount, influencing their capacity to climb hills.
Limiting Grade: The steepest grade a horse-drawn vehicle can climb without stalling depends on factors like the load, surface, and the animal’s pulling power.
Costing Grade: The grade at which a vehicle can coast without applying brakes depends on the road surface and vehicle type.
Trunkline Highway Grade: Highway engineers generally agree that a 6% grade is the maximum desirable on trunkline highways, unless substantial grading is required.
Gravel Road Thickness: A well-compacted gravel layer of 10 inches can support loads up to four tons, with thinner layers appropriate for lighter traffic.
Gravel Size: Larger gravel pebbles are more resistant to crushing but can make for a rough road surface.
Gravel Bonding: The cementing properties of gravel are not always dependent on the clay content.
Macadam Thickness: A standard eight-inch thick layer of macadam is typically adequate for medium traffic loads, with adjustments needed for heavier loads or inferior foundations.
Telford Foundation: This type of foundation uses large stones laid by hand and is often employed when the earth foundation is unstable.
Screenings: The finer portion of crushed stone used to bond broken stone roads is called screenings.
Concrete Strength: Concrete used for road surfaces should have a crushing strength of at least 2500 pounds per square inch.
Two-course Road: A two-course concrete road has a wearing course of high-quality aggregates and a lower course of less durable aggregates.
Concrete Expansion Joints: Expansion joints are typically built into concrete roads to accommodate temperature changes and prevent cracking.
Brick Bedding Course: A bedding course of sand or sand-cement mortar is used to level brick surfaces and accommodate variations in brick size and shape.
Filler: Fillers are used to prevent displacement of brick and prevent water penetration into the bedding course, and can be made of cement grout, bituminous materials, or mastic.
Asphaltic Material Consistency: Bituminous materials for road construction are classified by their consistency, ranging from road oils to asphalt cements.
Bitumen: Bitumen is the soluble portion of bituminous materials that gives them their cementing properties.

Statistics:

Average Farm Density: 6-8 families per square mile (with some areas reaching 20 families per square mile).
Motorized Traffic: Over 90% of rural highway tonnage is carried by motor vehicles.
Truck Operation Costs: Average daily costs for a 5-ton truck, including direct and indirect charges, range from $26.82 to $30.15.
Trunkline Railway Cost: Cost per ton-mile for hauling freight on trunk-line railways ranges from 1.7 to 4.4 mills per ton-mile.
Tractive Resistance: On a level road surface, the average tractive resistance for steel tired vehicles varies from 38 lbs. per ton for very good macadam to 218 lbs. per ton for muddy earth.
Gravel Road Thickness: 8-10 inches of well-compacted gravel can support loads up to 4 tons.
Macadam Thickness: A standard macadam surface for medium traffic is 8 inches thick.
Concrete Crushing Strength: Concrete for road surfaces should have a crushing strength of at least 2500 pounds per square inch.
Expansion Joint Spacing: Expansion joints in concrete roads are typically placed every 30 feet.

Terms:

Tractive Resistance: The force needed to move a vehicle over a surface.
Impact: The force created by the pounding of wheels on a road surface.
Coasting Grade: The grade at which a vehicle can coast without applying brakes.
Raveling: The process of a road surface breaking apart due to the loss of binding material.
Bitumen: The soluble portion of bituminous materials that gives them their cementing properties.
Asphaltic Concrete: A road surface mixture of graded stone, sand, and asphalt cement.
Screenings: The finer portion of crushed stone used to bond broken stone roads.
Telford Foundation: A type of road foundation using large stones laid by hand.
Mastic: A mixture of fine sand and a solid bituminous material used for fillers.
Expansion Joint: A gap built into a road surface to accommodate temperature changes and prevent cracking.

Examples:

Horse-drawn Traffic on a Hill: The text illustrates the concept of limiting grade by discussing the ability of a team of horses to climb a hill with a specific load, considering factors like pulling power and tractive resistance.
Sand-clay Road Construction: The text describes the process of constructing a sand-clay road surface by mixing clay with sand to achieve a specific composition, explaining the importance of achieving a proper balance between the materials.
Gravel Road Maintenance: The text describes the use of a planer, a specific type of road drag, to maintain the shape and smoothness of a gravel road surface.
Macadam Repair: The text describes the process of patching a broken stone road by loosening the surface, adding new stone and screenings, and re-rolling the surface.
Bituminous Surface Treatment: The text outlines the process of applying a bituminous coating to a macadam road to prevent raveling, detailing the cleaning process, the application of the binder, and the use of stone chips.
Penetration Macadam: The text explains the process of constructing penetration macadam, where bituminous binder is applied to a lower layer of broken stone, then coated with stone chips, and rolled.
Hot-mixed Macadam: The text describes the construction of hot-mixed macadam, where graded stone, sand, and a bituminous binder are heated and mixed before being placed and rolled.
Asphaltic Concrete: The text outlines the differences between two types of asphaltic concrete – Bitulithic and Topeka – highlighting their distinct compositions.
Concrete Road Cracking: The text discusses the common occurrence of cracks in concrete roads and the use of bituminous filler to seal them.
Brick Road Construction: The text describes the process of constructing a brick road, outlining the foundation preparation, bedding course application, brick laying, rolling, and filling the joints.

Conclusion:

“American Rural Highways” highlights the crucial role of roads in rural America and the evolving challenges of constructing and maintaining them. The text provides a comprehensive overview of various road types, construction methods, and maintenance techniques. It emphasizes the importance of adapting road design and construction to local soil and climate conditions. The text also sheds light on the ongoing shift in highway administration toward greater state and federal involvement, reflecting the growing complexity of transportation infrastructure in the United States. By understanding these principles, readers gain valuable insights into the complexities of rural highway development and the essential role of roads in shaping our society.

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