As you can see by your first reply, some view the unhindered rights of corporations to operate without any regulation, regardless of the impacts on others as one point of view....

Those who suffer through fifty or sixty train movements a day hearing 120 decibel train horns at all hours may have a different opinion. They would argue that others do not have the right to make a profit while imposing costs on others without compensation (the argument being that the noise reduces property values and hurts businesses who are not compensated by the railroads).

Remember that at one time, some folks opposed knuckle couplers and air brakes on trains as passing fads, and Federal regulations mandating these things to make trains safe was the work of jack booted thugs, out to destroy our capaitalist system.

The solution to many of these types of "non partisan" "political" policy issues probably would depend on how you approach the problem. Should this be required at all grade crossings regardless of the level of operations or costs? Or are there reasonable approaches that make sense, such as requiring reduced noise based on level of movements and community impacts. This is the basis for much of our "political" discussions of such non partisan political issues. How do we balance competing rights?

Look to use standards for requiring such mitigations to reduce negative externalities to others where possible. It's ususally better not to get into mandates of specific technologies or approaches, as it too often causes political influence to decide such things, and not necessarily for the benefit of the public, but more often for the vendor with political clout. It is oftem more efficient to use technology neutral standards allow for achieving such public policy goals in a more cost effective manner.

Look to use "policy" to require quiet zones or quient zone investments by the number of people affected, like train moverments per person in range of the sounds? Stay away from how it should be done. Standard setting for the safety, reliability, and interopability of the particular device, appliance, or system to acheive quiet zones is another important, but separate regulatory path, and those appliances that dont' work, or are not compatible, would be a separate performance criteria for a different regulatory approach.

In setting pollution standards there has been a view that technology neutral emsission standards (grams per mile/brake horsepower) to reduce pollutants has been a good approach. The standards require that locomotives reduce the level of pollutants they produce and we breath (without compensation from the polluter). Many feel this standards based approach is a better way to go, leaving innovation and entrepreneurship to figure our the most cost effective technological way to meet the standard, rather than specifying a particular technology.