Shaping a road surface to deflect water perpendicular to the traveled way rather than parallel to it.
Purpose: Outsloping prevents concentration of flow on road surfaces that produces rilling, gullying, and rutting.
Relative Effectiveness: Not enough interviewees rated this treatment. One interviewee commented that this is one of the few treatments that has both immediate and long-term facility and resource benefits.
Environmental/Implementation Factors: Sometimes after regrading, compaction does not occur due to low traffic volume which may cause sheet and rill erosion. Both public and administrative traffic should be curtailed during wet road conditions to prevent rutting and road sub-grade damages.
|To effectively drain water from the road surface|
|To prevent concentration of water|
|To prevent loss of control of water|
|To prevent gully and rill erosion|
On outsloped roads, accentuate the existing slope to 4% outslope and remove berms for maximum dispersal of water
On insloped roads, remove berms where road slope can be changed to outslope even for just a short segment
On insloped roads, waterbars may be required to break up the length of run that water is allowed to travel before being directed to a cross drain culvert. Waterbars may in some instances be installed against the prevailing road slope to reduce the possibility of a cascading effect from water being trapped in an insloped road prism. NOTE: Waterbars are not that effective on roads open to traffic. They are most appropriate on blocked roads.
|Outsloping is appropriate in almost all locations|
|Waterbars are appropriate in areas of high intensity burn and with steeper grades (greater than 10%)|
HOW TO OUTSLOPE ROADS AND INSTALL WATERBARS
Outsloping is typically accomplished with a grader or dozer. Waterbars can be constructed with grader, dozer, or backhoe. In these operations, incorporate excavated material into the roadway, and avoid sidecasting. Always insure that sufficient moisture exists to obtain compaction. Reference typical drawings for dimensions and specifications.
COSTS (1992 costs)
|Materials and Labor||Cost|
|Equipment Dozer, D6||$43.36/hr|
|Truck Driver (water truck)||$40.30/hr|
|Existing slope (inslope or outslope)|
|Material consistency (common, rip, blast)|
|Existing berm, vegetation in the berm|
|Production.... waterbars...4/hr 192 cost guide * Average cost/waterbar Public Works, $33 ea.|
Note: Add 25% for overhead and profit or travel and supervision. Add mobilization for all equipment, transport rate $75/hr, 1997 contracts.
|4 each / day - light|
|2 each / day - moderate|
|1 each / day - heavy|
The hazards associated with dozer and/or grader operations in the process of outsloping and installing waterbars include:
|Rollover, from working close to the road edge|
|Backing accidents, where backup warning devices are not operational and where appropriate warning signs have not been installed|
|The windrow left behind or between passes can be difficult to drive over and may contain large rocks that could damage the undercarriage of vehicles|