Why are there not more grade separations instead of at-grade railroad crossings, especially at crossings where the is a high volume of cars and trains, or where a number of accidents have occurred?

The cost of a typical grade separation can range between $1,000,000 and $7,000,000, depending on site conditions and the extent of needed private property acquisition. Funding constraints limit the widespread application of grade separations. The displacement of business and residences due to approach grading in the vicinity of an at-grade crossings may weigh heavily against the construction of a grade separation.