PLANNING HIGHWAY SYSTEMS: SELECTION OF ROAD TYPES 222
Object of a Road. Road Classification: Agricultural.
Recreational, Commercial, Military. Problem of the Road
Planner: Economy, Accommodation, Utilizing Existing Roads.
Essentials to be Considered: Ruling Points, Branch Lines and
Detours, Alternate Routes, Existing Highways and City Streets,
Vested Rights, Widening Roads and Streets, Railroads, Trolley
Lines, etc., Bridges, Culverts, Drainage, etc., Ruling Grades,
Esthetics. Motor Transport Efficiency Outline, Highway System
Unit: Arguments in Favor of National System -- Eliminates
Sectional Differences, Gives Continuous Roads, Military Roads,
Benefits of Example. State Systems -- Benefits. Procedure of
Laying out a Road System: Commission, Determining Factors,
Maps, Tentative System, Reconnaisance Survey -- What Shown,
How Taken, Instruments; Hearings -- Object; Final Location
-- Considerations, Traffic Census Advisable. Financial
Considerations: First Cost, Upkeep, Traffic Census: Affects
Location, Type of Road, Grades, Width, Foundations. Making a
Traffic Census: Variation of Traffic -- Number of Counting
Days, Hours Each Day, Weights, Observer’s Cards, Both Way
Count, Weather, Stations -- Location of. Classification
of Traffic: Object, Maximum Loads, Effect of Heavy Loads,
Influence Units of Traffic -- British, French, Other Countries,
Maryland, Massachusetts, Borough of Brooklyn; Suggested Form
of Traffic Sheet -- New Jersey. Destructive Factors: Density
of Traffic, Weight of Vehicles, Impact, Speed, Wrinkling,
Sprung and Unsprung Weight, Tires, Pleasure Cars and Light
Traffic to be Considered. Other Methods of Estimating the
Amount of Traffic: Area Served, Tonnage Arising. Distribution
of Traffic over Township Roads. Selection of a Suitable Type of
Road. Taxpayers Allowed to Assist in Selection, Engineers to
Suggest. Ideal Road: Qualities of -- Low First Cost, Durability
-- Materials and Design, Resistance to Traction and Tractive
Force -- Horse, Truck, Speed, Temperature, Roughness, Width
of Tire, Diameter of Wheel, Table of Resistances; Resistance
Due to Grade -- Formulas, Coefficient, Available Engine
Effort; Slipperiness -- Type of Pavement, Climatic Conditions;
Sanitariness -- Definition, Effect of Type of Road; Noisiness;
Acceptability. Some Types of Roads and their Qualities: Earth,
Sand-clay, Gravel, Macadam, Bituminous Macadam, Bituminous
Concrete, Brick, Concrete, Creosoted Wood Block, Asphalt Block,
Sheet Asphalt, Other Types. Comparison of Roads -- Specimen
Tables.