The town has to petition the FRA. In order for it to be approved the crossing with no horn must remain below a certain risk threshold that is calculated based on train frequency, vehicular and pedestrian traffic and existing grade crossing safety features. If the crossing will exceed the threshold then the town must submit a plan to install certain additional safety features in order to be approved. The latest innovation in this area has been the use of small islands in the median to contain traffic behind the crossing gates.
Otherwise the far more expensive option are four quadrant gates and/or additional warning lights.