Types of Bridges

Number of Bridges
Harford County maintains 222 Highway Bridges and 3 Pedestrian Bridges for a total of 225 bridges.

Highway Bridges
There are 156 Highway Bridges in our large bridge inventory. These bridges are over 20 feet clear span and are federally mandated to be inspected every 2 years.
Jerusalem Mill Pedestrian Bridge
The 66 Highway Bridges and 3 Pedestrian Bridges that are in our small bridge inventory are between 10 and 20 feet clear span. We also inspect these bridges every 2 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 any of the bridges that are 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 225 bridges because there is some overlap between the bridges in this breakdown.

The entire bridge inventory is shown in the index. It should be noted that there are some gaps in our bridge numbering system. This is due to a couple of reasons: 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.
Posted Bridges
Many bridges were built before the Maryland State Highway Administration (SHA) adopted their 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 2 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 in the process of being phased out.