Profiles are two dimensional descriptions of objects or phenomena. In civil engineering the traditional profile is a plot of elevations along a line or route vs. the distance along the route. The vertical scale is usually different than the horizontal scale by 10, 20, 50, 100 or some other convenient multiplier.

The same technique can be used to describe the other phenomena such as:

• Hydraulic Speed/Velocity or acceleration vs time or distance, etc.
• Revenue, Expenditure, Labour, Investment and other financial time histories.

Financial profiles are often taken at a point in time rather than as a time history. However they are done they can be concise and informative.

Velocity profiles are of particular interest to vehicle operators, route designers, and traffic engineers who may wish to tailor expected speed to curve radius, or curve radius to expected speed at each section of a route.

The usual design criteria of a minimum radius curves for a route is only valid if the route is designed for a constant speed for its entire length. A constant speed assumption fits most routes that have long haul traffic even with intermediate stops. However a constant speed assumption is not realistic for many situations . In such cases the geometry can be tailored to suit the speed profile.

Vertical alignment is fitted to the terrain profile as a series of uniform grades or tangents joined by vertical curves. The general design approach is to fit limiting or better grades and curves as close to the terrain as practical to optimize the cost of construction. Other factors such as minimum slopes for drainage, obstacle clearances, etc. constrain the final design.

Limiting and desirable maximum grades are set by the technology, operating conditions and climate. For motor vehicles on conventional highways using rubber tires, wet, icy, and snowy conditions limit maximum grade. The desired minimum speed, power to gross mass of the limiting vehicle, and the drive wheel / road surface characteristics limit maximum desirable grades.

Engine power (and fuel) is consumed going up and braking power is consumed going down grades. Keeping the grade as close to average between the beginning and ending of a route helps with fuel and braking consumption.

Links:

1. Vertical Alignment
2. plotting and graphing using ‘vs
3. General List of Transportation Topics
4. Intro. to Transport, a Physical and Quantitative approach
5. TOPICS included in MYSYS
6. Introductions to TOPICS included in MYSYS
7. Time Value and Engineering Economy Topics
8. Index of MYNET files

End to date, ams 971215