American Rural Highways Informative Summary

Overview:

Published in 1920, “American Rural Highways” by T.R. Agg provides a comprehensive analysis of the rural highway infrastructure in the United States during the early days of the automobile. The book delves into the administrative challenges of road building, highlighting the differences between township, county, and state systems. It examines the financial considerations of constructing highways, including special assessments, general taxation, vehicle taxes, and bond issues. The text also offers detailed explanations of various road types, including earth roads, sand-clay roads, gravel roads, broken stone roads, cement concrete roads, and vitrified brick roads. Agg outlines design principles for each type, emphasizing the importance of drainage and its role in preventing road deterioration. The book concludes with a discussion on maintenance practices for different types of surfaces, emphasizing the need for both patrol and gang maintenance.

Agg’s work highlights the rapid evolution of transportation systems in the early 20th century and the challenges associated with integrating new technologies, like the automobile, into existing infrastructure. He underscores the crucial need for comprehensive planning, proper construction techniques, and continuous maintenance for creating a robust and sustainable rural highway network.

Key Findings:

The Importance of Drainage: Proper drainage is crucial for all types of road surfaces, particularly in humid regions. Neglecting drainage leads to road instability and increased maintenance costs.
Impact of Motor Vehicles: The emergence of the automobile brought significant changes to highway design and maintenance. The need for smoother, more durable surfaces became paramount.
Shifting Administrative Systems: Highway administration in the United States was undergoing a transition from local to state and federal control, reflecting the growing importance of a national highway network.
The Evolution of Road Types: The book provides insights into the transition from simpler earth roads to more durable surfaces like sand-clay, gravel, macadam, and eventually concrete.
Maintenance as a Continuous Process: Agg stresses the significance of ongoing maintenance for all road types, emphasizing the need for regular inspections, repairs, and resurfacing to ensure long-term usability.

Learning:

Understanding Road Types: Readers will learn about the various types of road surfaces commonly used in the early 20th century, including their construction techniques, strengths, weaknesses, and appropriate uses.
The Importance of Drainage: The text emphasizes the critical role of drainage in road design and construction. Readers gain a comprehensive understanding of various drainage methods and their applications.
Highway Administration: Readers will learn about different levels of highway administration in the United States, from local townships to state and federal governments.
Road Design Principles: The book explains essential design considerations for rural highways, including alignment, grades, intersections, superelevation, and sight distances.
Road Construction Techniques: The text provides detailed explanations of construction methods for various road types, highlighting the importance of proper materials, compaction techniques, and quality control.
Maintenance Practices: Readers will acquire knowledge about different maintenance strategies, including patrol maintenance and gang maintenance, and the specific tasks involved in keeping various road types in good condition.
Historical Context of Highway Development: “American Rural Highways” offers valuable historical context, showcasing the evolution of highway construction and the challenges of adapting to the increasing demands of motor traffic.

Historical Context:

The text was written in 1920, a time when the automobile was becoming increasingly popular in the United States. The country was experiencing a rapid transition from horse-drawn transportation to mechanized vehicles, demanding improvements to existing road infrastructure. The need for a national highway system was growing, prompting calls for greater coordination between different levels of government.

Facts:

More than 90% of the tonnage on rural highways is carried by motor vehicles. (Pg 3) This highlights the growing impact of the automobile on road transportation.
The average rural family density in the United States was between 6-8 families per square mile. (Pg 4) This provides context for the traffic volume on rural roads.
Horse-drawn vehicles still accounted for a significant proportion of farm traffic in 1920. (Pg 4)
Motor trucks were increasingly used for long-distance freight haulage, exceeding 100 miles in some cases. (Pg 8)
The cost of hauling a ton of farm produce 10 miles to a railway station was equivalent to hauling it 1000 miles by rail. (Pg 9) This illustrates the inefficiency of unimproved roads.
The overhead charges for operating a 5-ton gasoline truck averaged $23.15 per day. (Pg 10)
The cost of hauling freight per ton-mile on heavy-traffic railways ranged from 1.7 mills to 4.4 mills. (Pg 11)
Township authorities typically manage 70% of the total road mileage in the United States. (Pg 14)
Many states limit the total amount of bonds outstanding for road construction by a constitutional limit. (Pg 15)
County boards often grant “county aid” to townships for bridge construction, typically paying for half the cost. (Pg 16)
State highway departments are funded through a combination of general taxation and automobile license fees. (Pg 17)
Federal aid for road construction is granted to states on the condition that they expend an equal amount on the projects. (Pg 18)
State highway departments often review contracts for materials and construction entered into by county and township authorities. (Pg 19)
Special assessments on private property are frequently used to finance rural highway improvements, with a maximum of 25% of the total cost. (Pg 20)
In the “zone method” of assessing, property closer to the improved road receives a higher assessment rate. (Pg 21)
General taxation is used to cover a portion of the maintenance costs for both township and county roads. (Pg 24)
The desirable thickness for a gravel road surface varies from 6 inches to 10 inches, depending on traffic and soil conditions. (Pg 84)
A standard eight-inch thick macadam surface is typically adequate for roads carrying loads up to four tons. (Pg 90)
Broken stone roads require a well-drained and stable earth foundation. (Pg 92)
Cement concrete roads should have a crushing strength of at least 2500 pounds per square inch. (Pg 101)

Statistics:

The annual precipitation in humid regions of the United States is typically greater than 30 inches. (Pg 29)
A well-drained earth foundation for a road should have a layer of dry soil at least two feet thick, or three feet thick for soils with high capillary action. (Pg 30)
A 45-minute rainfall event will typically result in all the water running off, as the soil will reach saturation. (Pg 32)
The bottom of a road ditch on a 1% grade in a humid region should be at least 3.5 feet lower than the traveled surface. (Pg 32)
A typical road drag can smooth the surface of an earth road effectively within a day or two after a rain. (Pg 71)
A 10-ton roller is generally considered ideal for compacting broken stone roads. (Pg 95)
Expansion joints for concrete roads are typically spaced every 30 feet. (Pg 104)
The standard rattler test for paving brick involves 10 brick, 300 lbs. of cast iron spheres, and 1800 revolutions. (Pg 108)
A 5-inch thick concrete foundation is typically sufficient for brick roads on well-drained soils. (Pg 109)
A sand bedding course for brick roads should consist of fine-grained sand, with all particles passing an 8-mesh sieve. (Pg 111)
The bituminous filler for brick roads is typically poured hot and worked into the joints with squeegees. (Pg 113)
The ideal quantity of bituminous binder for a surface treatment of macadam is about 0.5 gallons per square yard. (Pg 122)
A typical penetration macadam surface consists of a 6-inch thick lower course of broken stone and a 2.5-inch thick upper course. (Pg 123)
The hot-mixed macadam wearing course is typically 2 inches thick after rolling. (Pg 127)
The asphaltic concrete mixture for the Topeka type typically contains 25% voids. (Pg 128)

Terms:

Caliche: A type of soil containing calcium carbonate that serves as a binder in road construction.
Top-Soil: A naturally occurring mixture of sand and clay often used for road surfaces.
Screenings: The fine material produced by a crusher, used as a binder in macadam construction.
Telford Foundation: A type of road foundation using large stones placed by hand and compacted for stability.
Rattler Test: A standard test for determining the durability of paving brick using a rotating drum with cast iron spheres.
Expansion Joint: A gap in a pavement designed to allow for expansion and contraction due to temperature changes.
Mastic: A mixture of fine sand and bituminous material used as a filler in pavements.
Bitumen: The soluble portion of bituminous materials, responsible for their binding properties.
Penetration Macadam: A type of macadam construction where a bituminous binder is applied to penetrate the stone layers.
Seal Coat: A layer of hot bituminous material applied to the surface of a road to provide a protective coating.

Examples:

Ball Clay Test: To determine the suitability of a clay as a binder, a small amount is mixed into a stiff mud and formed into a ball. The ball is then immersed in water, and its ability to retain its shape indicates its binding potential. (Pg 75)
Gypsum as a Binder: Deposits of clay or gravel containing gypsum can be used as a binder in combination with sand or gravel. (Pg 75)
Oversize Gravel Removal: When gravel deposits contain pebbles larger than a 3.5-inch ring, these stones can be removed during loading or spreading, or screened out at the pit. (Pg 83)
Clay Binder Addition: Gravels deficient in bonding material can be improved by adding clay binder during construction. (Pg 84)
Telford Foundation: In areas with weak soil, a Telford foundation is used, where large stones are placed by hand and the gaps filled with smaller pieces. (Pg 94)
Rolling Macadam: The layer of broken stone in macadam construction is typically rolled in two layers, with the lower layer compacted before the upper layer is placed. (Pg 94)
Expansion Joints in Concrete: To accommodate temperature changes, expansion joints are typically built into concrete roads, using sheets of bituminous material or wooden strips. (Pg 104)
Surface Treatments for Macadam: To prevent raveling in macadam roads subjected to motor traffic, a bituminous binder is applied to the surface, followed by a layer of stone chips. (Pg 120)
Patching in Penetration Macadam: Areas of the penetration macadam that fail prematurely are repaired by loosening the stone, adding new stone, and applying bituminous material. (Pg 125)
Hot-Mixed Macadam: In this type of road construction, broken stone or gravel is mixed with a hot bituminous binder, then placed and compacted. (Pg 126)

Conclusion:

“American Rural Highways” offers a valuable glimpse into the development of rural road infrastructure in the early 20th century. The book highlights the challenges and innovations associated with adapting to the increased use of automobiles and the demand for more durable and efficient transportation systems. The text emphasizes the crucial role of proper design, construction, and maintenance practices for creating and sustaining a robust highway network. Readers gain a comprehensive understanding of various road types, drainage techniques, and administrative systems, recognizing the importance of planning and investment in building a sustainable highway infrastructure.

Learn more