Review details of the slab and curb reinforcement of the existing bridge to determine if the slab edge is capable of being retrofitted with an adequate new railing. Note in particular:

Slab thickness and overhang length;
Curb width and height and reinforcement; and
Bridge abutment wingwall conditions.

Evaluate the effect of a full-strength retrofit on the shoulder width of the bridge. Ensure that a reduction in effective shoulder width or in sight distances at adjacent intersections will not affect safety. Also consider the following:

Bridge width, alignment, and grade;
Type, aesthetics, and strength of existing railing; and
Bridge length and its potential for posting speed limits.

Evaluate details of the location, such as the following:

Bridge structure’s height above lower terrain or waterway;
Approach roadway’s width, alignment, and grade;
Position of adjacent streets and their average daily traffic;
Posted speed at bridge, average daily traffic, and percentage of truck traffic; and
Accident history on the bridge.

Carefully review details of potential retrofit designs, such as the following:

Placement or spacing of new anchor bolts or dowels;
Reinforcement anchorage;
Approach guard fence post positioning; and
Shoulder width required by the new railing.