practical design reference? 1

[ACtrafficengr]

Want to see something amusing? Watch a bridge guy and a traffic safety guy try to design a 3R project. Well, I bet it would be funny if you're not one of them. If it were a new alignment, it would be a lot easier.

What we need is a book of practical advice on what to do when AASHTO doesn't help. For example, we have a sideroad approaching on a right curve, and the main road is graded the other way. What is an acceptable rate of change for warping the curve super to meet the mainroad grade?

I should mention that the traffic volume (~550 - 850 vpd) doesn't warrant expensive fixes like realignment, and the budget doesn't allow it anyway.

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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."

Wm. Phelps Eno, ca. 1928

 

[Maury]

Contact your state's highway department (check website). Most have 3-R guidelines that less stringent than the AASHTO requirements.

 

[ACtrafficengr]

That doesn't answer my question.

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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."

Wm. Phelps Eno, ca. 1928

 

[jeremyk55]

.015 in 25 ft is an appropriate rate for 25 mph design speed based on the green book tables. However, since this is a low volume road approaching what I assume is a stop condition, a transition of 0.017-0.02 in 25 could be warranted. Hope this is not too late to help.