An example of differentiating policy in practical ways: crude oil by railroad

In terms of the reality that "one size doesn't fit all" in planning, here is an example of how to plan and apply policy differentially, depending on particular sets of needs.

Cities and residents in cities are very concerned about transportation of chemicals on railroad systems that travel through cities or to urban ports, because spills and accidents can be incredibly dangerous ("Seattle joins debate about limiting oil-by-rail," Seattle Times), as was proven in Lac-Mégantic, Quebec, where 47 people died when a train carrying crude oil derailed and touched off an inferno that incinerated portions of the town ("The deadly secret behind the Lac-Mégantic inferno," special report, Toronto Globe and Mail).

While there has been resistance in some sectors of the industry to safety changes to railcars transporting chemicals ("A lot at stake in tank-car design discussions," Progressive Railroading) such as crude oil because of the cost, it turns out that it would be "relatively easy" to create a differentiated policy for the specific requirements of railcars for crude oil and chemical transportation, by focusing higher requirements on more risky items, as measured by the  volatility of the chemicals being shipped.

It turns out that Bakken crude oil is significantly more volatile than other types of crude oil.  See "Bakken Shale Oil Carries High Combustion Risk" from the Wall Street Journal.  From the article:

The Journal analyzed data that had been collected by the Capline Pipeline in Louisiana, which tested crude from 86 locations world-wide for what is known as vapor pressure. Light, sweet oil from the Bakken Shale had a far higher vapor pressure—making it much more likely to throw off combustible gases—than crude from dozens of other locations.

Neither federal law nor industry guidelines require that crude be tested for vapor pressure. ... According to the data, oil from North Dakota and the Eagle Ford Shale in Texas had vapor-pressure readings of over 8 pounds per square inch, although Bakken readings reached as high as 9.7 PSI. U.S. refiner Tesoro Corp., a major transporter of Bakken crude to the West Coast, said it regularly has received oil from North Dakota with even more volatile pressure readings—up to 12 PSI.

By comparison, Louisiana Light Sweet from the Gulf of Mexico, had vapor pressure of 3.33 PSI, according to the Capline data.

Note that Canadian regulators have made a similar determination with regard to the tragic incident in Quebec ("Canadian Regulators Say Oil in Train Accident Was as Volatile as Gasoline," WSJ).

The solution is to require higher transport safety requirements according to the volatility of the product as determined by the vapor pressure content.