Access to roadway

[roberttx]

Hi,

I have a question here. I have been trying to model the access to an existing roadway from a new one. The problem is an existing parallel canal is to remain untouched, and it leaves no room for a vertical curve overpassing with a bridge with a steep slope on a short vertical tangent conecting to the roadway (15 feet @ 13%). Is this acceptable?

Roberttx

 

[RWF7437]

Acceptable to who ?

Boat ramps are often built on a 12% to 15% grade so the grade is not too steep to drive if it is short. But such grades may not be acceptable at a road intersection where sight distance is also a consideration.

Maybe a conversation with the agency who will review and approve your plans mught be useful ?

Another option might be to alter the existing roadway if that is possible.

 

[wolfhnd]

I think that the differnce in grade between the connection and the main roadways cannot have that kind of change in grade in just 15 feet. You need to have some sort of transition even if you don't have a vertical curve.

 

[KRSServices]

Wow....that grade is too high. The highway authority likely specifies a transition (maybe 2% for about 5m from the shoulder to the property). But during inclement weather (rain, snow) that access is going to be a hazard or the user will not be able to climb it, particularly if it is to remain gravel. KRS Services

http://www.krs-services.com

 

[RWF7437]

roberttx,

Is any of this helping ?

Is there a highway authority you must satisfy ?

The grade is steep but, is this even a highway, as KRSServices seems to think ?

Steep grades can be tolerated for short distances ( e.g in parking structures ) but not easily on "highways" or even local streets. In San Francisco people drive very steep grades with sharp "breakovers" all the time. The wear and tear on brakes, clutches, and nerves has never been calculated.

We all sure wish you could send an attachment, in the form of a simple sketch, as an attachment. Some websites do allow this.

Hope you can get it figuerd out.

Russ

 

[roberttx]

Hi,

As a matter of fact, the roadway to which I'm connecting is a TxDOT maintaned roadway and the channel is a facility by a local water district. I've figured some solutions the work this around:

-Use a series of culvert boxes to contain the flow on the channel and pass over them (this solution apparently is not supported by the water district)
-Leave the channel untouched with a small bridge connecting to the existing roadway (which leads to a steep slope into the roadway)
-Modify a portion of the existing alignment in the intersection (which usually takes more time for permission from state authorities)

I appreciate your responses.

Roberttx

 

[trafficPro]

Can you relocate the channel away from the roadway for a short distance, so as to provide a greater intersecting roadway length between channel and bridge, and permit a lesser grade bridging?
Also check the rollover to prevent vehicles bottoming on the peak.
Good Luck
TrafficPro

 

[reddog99o]

That grade would appear to be too steep. Probably excessively, but the point is made elsewhere as to what authorities you must satisfy. Safety should be a concern here. If you are in a cold area, you've got to think of ice on that slope in the winter. Err here on the side of conservatism. Personally, I wouldn't touch that grade in any kind of environmemt.

Best of Luck, R.A. Hassett, P.E.
rah1616@hotmail.com