Bridge Road Gradient

Very speed dependent.

http://www.google.com/search?hl=en&q=%22bridge+construction%22+%2Bstandards&btnG=Google+Search

Max.12%

i.e you rise 12' in 100'

To avoid overload damage to heavy vehicles' propeller shafts.

This is very much speed dependant. At 120 KPH a 12% ramp will produce an upwards vector of 14.4 KPH, which will tend to require very long gradations to flat sections or cars will be in the air

The gradiant on the bridge deck needs to be a continuation of the roadway profile grade. You can not just design a roadway profile up to the begining of the deck, you must use accepted roadway profile engineering to design the roadway through the bridge, otherwise ride quality will suffer and you will induce impact loading to the bridge structure.

Correct. One of the aspects that must be considered for the approach roadway is the bridge deck, but there are many other factors that effect the grade and length of the approach roadway (i.e. vehicle speed, hoz. and vert. sight distance, type of bridge deck surface, etc.).

If the deck is level, the approach must be level. If the deck possesses a gradient, the approach should match it on both sides. If it is not possible to match the deck gradient with a straightaway approach, then the both the bridge and approach gradients should be calculated to the speed of the oncoming traffic, and guardrails added on the approaches.

Mark

It all depends on the bridge type the amount of road you have before the bridge and the span of the bridge. Ideally you would have as flat an approach as possible. You have to allow for any bend in the approach road the nature of the surrounding land hedges trees. The best is to have any slope as flat as you can get away with.