Types of Bridges
Harford County maintains 253 bridges - 229 highway bridges and 24 pedestrian bridges.
Highway Bridges
Our large bridge inventory includes highway bridges that have more than a 20-foot clear span and are federally mandated to be inspected every two years.
The small bridge inventory - bridges with a 10- to 20-foot clear span - are also inspected every two years even though there is no federal mandate to do so.
All structures under 10 feet clear span are not a part of the Bridge Program, but are included in our Culvert Program.
All of the bridges cross over streams except for four bridges that cross over railroad tracks.
Note: The Harford County Bridge Inventory does not include bridges in the State of Maryland's bridge inventory. The state's bridges are generally on numbered routes such as MD 7 or I-95.
Types of bridges
| Number of Bridges | Main Superstructure Members | Bridge Deck | Wearing Surface |
|---|---|---|---|
| 3 | Steel Beams, Composite | Concrete | Asphalt |
| 26 | Steel Beams, Composite | Concrete | Concrete |
| 37 | Steel Beams, Non-Composite | Concrete | Asphalt |
| 9 | Steel Beams, Non-Composite | Concrete | Concrete |
| 3 | Steel Girder, Floor Beams, Stringer | 3 Types | 3 Types |
| 12 | Steel Beams | Corrugated Steel | Asphalt |
| 5 | Steel Beams | Timber Plank | Timber Plank |
| 4 | Steel Beams, Encased in Concrete | Concrete | Concrete / Asphalt |
| 1 | Steel Beams, Truss Facade | Timber Plank | Timber |
| 1 | Steel Truss, Bowstring | Timber Plank | Timber Plank |
| 3 | Steel Truss, Prefabricated | Steel Plate | Non-Skid Material |
| 2 | Steel Truss, Prefabricated, Pedestrian | Timber Plank | Timber |
| 2 | Iron Truss, Pony | Timber | Timber |
| 4 | Iron Truss, Through | Timber Plank | Timber Plank |
| 1 | Iron Truss, Through, Pedestrian | Timber Plank | Timber Plank |
| 13 | Steel Tank Cars | N/A | Asphalt |
| 21 | Corrugated Steel Pipe / Pipe Arch | N/A | Asphalt |
| 20 | Concrete Prestressed Beams | Concrete | Concrete |
| 11 | Concrete Prestressed Beams | Concrete | Asphalt |
| 6 | Concrete Slab | Concrete | Concrete |
| 7 | Concrete Rigid Frame | Concrete | Concrete |
| 9 | Concrete Solid Arch | Earth Fill | Asphalt |
| 1 | Concrete Ribbed Arch | Concrete | Concrete |
| 4 | Concrete Box Culvert | Concrete | Concrete |
| 18 | Concrete Box Culvert | Concrete / Earth Fill | Asphalt |
| 2 | Reinforced Concrete Pipes | N/A | Asphalt |
| 5 | Laminated Timber Deck | Laminated Timber | Asphalt |
| 1 | Laminated Timber Beams | Laminated Timber | Asphalt |
| 1 | Timber Covered Bridge / Steel Beams | Laminated Timber | Timber |
Note: The bridges in the above categories will add to more than 229 bridges because there is some overlap among them.
The entire bridge inventory is shown in the index. It should be noted there are some gaps in our bridge numbering system. Some roads were abandoned and the bridges were removed or abandoned or the bridge inventories were upgraded in 2007 and some of the smaller “bridges” were downgraded to the culvert inventory.
Weight limit postings
Many bridges were built before the Maryland State Highway Administration (SHA) adopted its latest standard design vehicles. Older bridges were designed for vehicle loads that may be considered as substantially substandard when compared to today’s standard vehicle loads. Therefore, many of these older bridges cannot safely carry the heavier SHA design vehicles.All bridges were analyzed using the latest standard design vehicles. The available bridge members’ load capacities, after reducing them for the applied dead load of the bridge, were compared to the applied live loads of the design vehicles. The bridge does not need to be posted if the remaining capacity of all of the critical members of the bridge exceeds the applied vehicle live loads on those members.
When the available member load capacity for any member is less than the applied live vehicle load, the bridge must be posted. Then the bridge is posted in the field for two weight limits - the single unit truck (panel truck) and the combination unit truck (tractor trailer). There are some older gross weight posting signs at some bridges, but they are being phased out.