To restore the confidence of its passengers and curtail train delays, the Great Northern built more and longer snowsheds along the route. But these additional structures created new troubles, trapping smoke and hindering visibility. In addition, summer's heat caused the snowsheds to become tinder dry and vulnerable to sparks from passing trains.

What were the negative effects of using snowsheds? Check all that apply.

trapped smoke
blocked visibility
more frequent avalanches
an increase in blizzards
an increased danger of fires