The directive comes from Employment and Social Development Canada. The order is part of the investigation into last September's fatal collision between a double-deckerOCTranspo bus and a VIA Train in Barrhaven.
The Transportation Safety Board is responsible for investigating the cause of the crash, but ESDC is looking into the incident from a workplace safety perspective.
It has directed the city to assess and remove any hazards near such crossings that could obstruct sightlines.
The city's chief clerk and solicitor says Ottawa will immediately comply with the order.
At the site of the fatal crash, the city has already cleared out brush and dead trees to improve visibility and sight lines. The speed limit along the Transitway approaching the crossing was also lowered from 60 kilometres per hour to 50 kilometres per hour in both directions, and another warning light was added.