Diamond Crossings - O.W.L.S. Crossing Design

One-Way Low-Speed diamond frogs are used in their namesake diamonds, often referred to as OWLS diamonds. These types of frogs are analogous to jump frogs in turnouts: the higher-trafficked line crosses the diamond on a normal rail surface in tread-bearing mode, and the lower-trafficked line crosses over the higher-trafficked line in flange-bearing mode.

Because there is no flangeway gap to cross on the higher-trafficked line, vehicles using this line can cross the diamonds at the maximum speed allowed by the track design. Because the lower-trafficked line is in a situation where gauge restraint is reduced and because it has to cross over the flangeway gap for the higher-trafficked line, vehicles using this line are limited to speeds at or below 10 miles per hour. OWLS diamonds are commonly used where a rail line with very little traffic operating at low speed crosses a rail line with considerably more traffic operating at higher speeds.

The secondary run flange bearing surface uses explosion hardened manganese castings.

The One-Way Low Speed (OWLS) crossing is used at locations where the traffic on the secondary track has low tonnage, speeds not exceeding 10 MPH, and very few trains.
The high impacts associated with wheels jumping the flangeway gaps on conventional crossings are significantly reduced with the OWLS crossing by the use of flange bearing ramps on the secondary track. This allows the wheel flange to run over the top of the mainline which eliminates the flangeway gaps on the mainline track.
The elimination of flangeway gaps and joints provides for a continuous running surface on the mainline track allowing trains to run without speed restrictions.
Impact reduction significantly reduces maintenance compared to conventional crossings.
The mainline run uses high strength head hardened rail.

The secondary run flange bearing surface uses explosion hardened manganese castings.