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Here is a photo of a railroad crossing near a road intersection.

Traffic, Rail Lights out of Sync at Fruitvale Avenue Crossing

The road signals are mounted to slender poles (or even suspended from a cable). Maintenance workers can access the road signals with a truck-mounted boom lift. In contrast, the poles that support the rail crossing signals are built much sturdier and also support a ladder and catwalk. (Ladders and catwalks seem to be common on railway operating signals, too.)

Since there are many more signals than workers, it seems like the total cost to outfit the workers with boom lifts would be cheaper than making every signal easily accessible.

I realize that road and rail signals developed independently, but their common engineering criteria (to hold a light up in the air) should have resulted in road and rail converging on a single lowest-cost solution.

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For a start, not all rail line traffic signals are like the ones in your picture - there is no uniformity.

Over-the-road signals will tend to be more common in high road traffic situations and in more populous regions than in low traffic or rural areas.

By having traffic lights over the road like that, at rail intersections, makes the intersection more noticeable to road users.

Collisions between trains and road vehicles tend to be more devastating and disruptive than collisions between just road vehicles. Making the rail intersection more obvious & noticeable to road traffic is an attempt to mitigate the possibility of a collision between a train & road vehicles.

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  • $\begingroup$ Road signals are also over the road, but without the huge truss. There's cheaper ways to make it more obvious, such as bright paint. $\endgroup$ – Spencer Joplin Apr 2 '17 at 8:47

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