Acceleration Rates

What if they asked the acceleration of a bus and didn't give out anymore info (This also applies to a car, semitrailer etc..), Where would I find this type of information

you can find average acceleration rate (for passing sight distance) and average deceleration rate (for stopping sight distance) for car from chapter 3 of the green book.

I did not find defaults for acceleration rate in Ch. 3. But CERM 74-5 gives this data: accel-11.2 ft/sec and decc.-14 ft/sec

They can ask for example how long of a distance in feet does it takes a school bus to go from 0 to 40 mph. The only place I found the rates was the ITE 5th edition. The 6th edition doesn't seem to have them anymore.

kenny911 said:

What if they asked the acceleration of a bus and didn't give out anymore info (This also applies to a car, semitrailer etc..), Where would I find this type of information

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k9, I don't think you'll see this type of a question without more information provided. Do be familiar with the uniform acceleration formulas where you could be given three variables (accel, time, initial/final speed, distance) and asked to solve for one of the other variables.

Ambrug20 said:

I did not find defaults for acceleration rate in Ch. 3. But CERM 74-5 gives this data: accel-11.2 ft/sec and decc.-14 ft/sec

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Amb, I think you mean ft/sec^2 (seconds squared). But in AASHTO GDHS page 111 states to use 11.2 ft/s^2 as a recommended decel rate for stopping distance. Accel rates for passing are found on page 120 Exh 3-5 - looks like around 1.45 mph/s

Ambrug20 said:

1. Use Sb=V12 - V22/ 30 (f-g) , Where V is mph,Sb is distance, f is 11.2/32.2=0.35 See CERM p. 74-5. I do not have ITE, but Goswami p.655 describe the case.
   

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Sb is braking/skidding distance.

I think you mean V1^2 - V2^2 (minus, not times). Also, I'd write it as (f +/- g) since the grade, g, can be positive or negative. f isn't always .35. Coefficient of friction, f, is a function of the pavement type/material.