Adamson, R. B. 1989. Low water crossings:
an inexpensive alternative for low volume roads in northern Ontario.
Abstract: Water crossings are a significant component of access road construction and maintenance costs. Design of such crossings takes into account predicted streamflows during extreme conditions. If culverts are used, much of the culvert capacity is not used during most of the life span of the crossing. Low water crossings are believed to be an environmentally sound alternative for low volume roads, as they are designed to allow periodic flooding over the road under extreme streamflow conditions. This report describes the installation of a low water crossing in northern Ontario. The type of crossing is known as a vented ford, consisting of a dip in the road with small culverts to handle normal flow, a roadbed and fill designed to resist erosion and to act as a spillway under extreme flooding, and precast barrier walls on the downstream side of the roadway.
Keywords: low water crossing; stream crossing design; road design and construction; road
· Askin, Robert
W. 1992. Armoured fords: an alternative drainage crossing
system for debris torrent prone mountain channels. Proceedings
of the international mountain logging and eighth Pacific Northwest skyline
symposium. Bellevue, WA. Editors Schiess, Peter and Sessions,
Abstract: This paper reports on the development of an armoured ford crossing for a steep, debris torrent prone drainage channel in the Catherine Creek Watershed on Vancouver Island, British Columbia. The engineering design considered the natural hydrologic, geomorphic, and hydraulic characteristics of the steep channel. The erosion, transport and depositional features of the channels were identified. From this, peak discharge and associated debris torrent magnitudes were estimated. An armoured ford was designed in July 1992, and constructed in August 1992 within a section of channel that had a natural gradient of 15 degrees (27 percent). Performance monitoring of the drainage crossing system will be carried out over the 1992/93 winter season. (A)
Keywords: low water crossing; drainage; debris flow and control; channel; stream crossing; drainage crossing; road
· Coghlan, G.
and Davis, N. 1979. Low water crossings. Low
Volume Roads: Second International Conference. Washington, D.C.
Abstract: This paper provides a rationale for planning and constructing low water crossings on low volume roads. Fords, fords with culverts and crossings on low structures are described. Examples are given of good and poor designs using different types of materials and involving a variety of environmental considerations. Examples come from National Forests in Minnesota, Missouri, West Virginia and New Hampshire. (A)
Keywords: low water crossing; road design and construction; road
· Keller, Gordon.
1983. Unpublished work. Low water crossings (Selection, design,
and construction of low water crossings). 24p.
Abstract: Types of low water crossings are enumerated and described. Tradeoffs among culverts, bridges, and fords are described. Determination of design flows, culvert design, Manning's equation, scour conditions, and riprap design are briefly discussed. Bridge site examination form (R5-7700-71, rev 7/75), nomographs for computing flood discharge in California, solution of Manning's equation, headwater depth for CMP culverts and arch culverts, and a chart for size of stone that will resist displacement for various velocities and side slopes are included. A section on soil filter design is also attached. (C)
Keywords: low water crossing; stream crossing; road; culvert; hydraulics
· Warhol, Terry
and Pyles, Marvin R. 1989. Low water fords: an alternative
to culverts on forest roads. Presented at the 12th Annual
Council on Forest Engineering Meeting. Coeur d'Alene,
Abstract: Low-water fords are a cost effective way of providing stream crossings for many forest roads. It is expected that low-water fords will require less maintenance, and are less likely to experience wash-out failure than a culvert installation. A list of design considerations is presented, along with the results of a survey of low-water ford installations from the Cascades mountains of Oregon. Fords have recently been constructed on watersheds from a few acres to over 4 square miles in area throughout an elevation range that includes both rainfall and snowmelt dominated runoff regimes. About 30 percent of the surveyed fords had experienced some erosion damage, but most damage appeared related to poor construction or inadequate design. (Author's abstract)
Keywords: stream; stream-crossing; low volume road; watershed; low-water ford; culvert installation; culvert; wash-out failure; erosion damage; Oregon; Cascade Mountains; low-water ford installation; road; regional
· Warren, Melvin
L. Jr. 1998. Road crossings as barriers to small-stream
fish movement. Transactions of the American Fisheries Society.
Abstract: We used mark-recapture techniques to examine the effects of four types of road crossings on fish movement during spring base flows and summer low flows in small streams of the Ouachita Mountains, west-central Arkansas. We assessed movement for 21 fish species in seven families through culvert, slab, open-box, and ford crossings and through natural reaches. We detected no seasonal or directional bias in fish movement through any crossing type or the natural reaches. Overall fish movement was an order of magnitude lower through culverts than through other crossings or natural reaches, except no movement was detected through the slab crossing. In contrast, open-box and ford crossings showed little difference from natural reaches in overall movement of fishes. Numbers of species that traversed crossings and movement within three of four dominant fish families (Centrarchidae, Cyprinidae, and Fundulidae) also were reduced at culverts relative to ford and open-box crossings and natural reaches. In spring, retention of fishes was consistently highest in stream segments upstream of crossings and lowest in downstream segments for all crossing types, a response attributed to scouring associated with spring spates. Water velocity at crossings was inversely related to fish movement; culvert crossings consistently had the highest velocities and open-box crossings had the lowest. A key requirement for improving road crossing designs for small-stream fish passage will be determination of critical levels of water velocity through crossings.
Keywords: road crossing; fish movement; spring base flow; summer low flow; stream; Ouachita Mountains; Arkansas; United States; culvert; slab crossing; open-box crossing; ford crossing; Centrarchidae; Cyprinidae; Fundulidae; scouring; spring spate; water velocity; culvert crossing; culvert hydraulics; hydrology; regional; road; culvert; fish passage