Ron’s Rant #4 – Why Cantilevers?
Last week’s rant spoke of the cone of vision on a horizontal plane. This week’s subject questions the value of using cantilevered structures when the cone of vision restricts the vertical plane view of warning lights placed on these expensive structures. The picture above shows a rail crossing with two sets of cantilevers, one on each side of the railway. These structures are designed to support distant views of signals not near view approaches to a crossing. In fact, Transport Canada suggests a distant view of 15.5 to 18.5 m minimum dependent upon the height of cantilever over the roadway. The minimum is designed to put the signal lights within the drivers’ cone of vision: and again, these values were set without due consideration of vehicle limitations. As a taller person in a smaller car, I have difficulty seeing overhead traffic signals when at an intersection. So, what benefits do the cantilevers provide at the above pictured installation?
In this instance there is no straight on road approach from either side of the crossing and there is little benefit to drivers of vehicles making a right-hand turn onto the railway crossing from the highway. The extra lights are a marginal benefit that would be improved if mounted on a left-hand mast closer to driver eye level. And for vehicles approaching from the left or straight on? Whoops, there are no vehicle approaches from the left or straight on.
And if you consider vehicles that approach from the forest side of the crossing: There are two angled road approaches that converge on the crossing. Because of the trees blocking view lines on those approaches, the cantilevered lights again have no benefit on that side that could not be served better by closer to driver eye level signals.
So why were the cantilevered lights installed here? To comply with the new Canadian Grade Crossing Regulations and Standards which state that they must be used if the distance from the centerline of the two-way two-lane traffic roadway to the center of the right-side signal mast exceeds 7.7 meters. In every instance that a road closely parallels a railway, the right-hand turn radius of the road shoulder will upset this criterion and require cantilevers to be constructed, even if there is no road approach that would benefit from a distant view of the lights supported by the cantilever.
I have seen many crossings installed with totally compliant flashing lights and bells with cantilevers on a highway similar to the one pictured above, only in far too many instances there were no gates installed. Left hand turns over the crossing required drivers to first find a gap in traffic and then immediately detect the flashing lights and stop if there was a train approaching. On one very new crossing installation, a young mother was killed by a 50mph freight train that was approaching from behind her as she tried to make a left hand turn over a crossing. She had little or no chance to pick up a view of the overhead flashing lights in the 10 to 15 meters her vehicle travelled after shooting a gap through opposing road traffic. Gates could have been installed at that location, a five-fold improvement to safety over flashing lights, saving construction costs, and almost for sure, saving a life.
So, next time you look at a crossing, don’t just consider compliance with the minimum standard. There may be better solutions that can be deployed at even less cost. Next week, I ask why we MUST install gates at all crossings that have a cross-product (vehicles times trains per day) exceeding 2000. Would not a risk-based criterion be better used to determine priorities?
If you have any questions, please send them along on LinkedIn or you can comment using the form on my website: RoadRailEng.com
Have a safe week – Safety for Life!