At-grade crossings introduce conflict points, and grade separation should be sought, as most path users expect continued separation from traffic. The greatest conflicts occur where paths cross freeway entrance and exit ramps. Path curves to improve visibility at signalized intersection When grade separation structures cannot be justified, signalization or other measures should be considered to reduce conflicts. Good sight distance must be provided so vehicle drivers can see approaching path users. Undercrossings should be visually open for the personal security of users.
Illumination is needed in areas of poor visibility.
If the roadway is elevated, an undercrossing can be constructed with little or no grade. They are often less expensive to build. They may present security problems, due to reduced visibility. They may require drainage if the sag point is lower than the surrounding terrain. This can be lessened if the road is built in a cut section.