An In-Depth Look at Lake Minnetonka Bridges on the Anniversary of I-35W Disaster

Five years ago today, the way both the state and nation looks at bridges changed forever.

The I-35W bridge spanning the Mississippi River in Minneapolis collapsed on Aug. 1, 2007—killing 13 people and injuring another 145.

In the immediate aftermath, federal and state authorities revamped the way bridges are inspected and ultimately graded for safety.

Today, five years later, the Lake Minnetonka area is home to seven bridges the Minnesota Department of Transportation and federal authorities deem problematic. Two are classified as being structurally deficient, while the other five have been found to be functionally obsolete. Definitions of both terms, provided by the National Bridge Inventory, are listed below:

• Functionally Obsolete—A status used to describe a bridge that is no longer by design functionally adequate for its task. Reasons for this status include that the bridge doesn't have enough lanes to accommodate the traffic flow, it may be a drawbridge on a congested highway, or it may not have space for emergency shoulders. Functionally Obsolete does not communicate anything of a structural nature.
• Structurally Deficient—A status used to describe a bridge that has one or more structural defects that require attention. This status does not indicate the severity of the defect but rather that a defect is present. Please see the Structural Evaluation and the Condition ratings of each bridge Deck, Substructure, and Superstructure for details of the nature and severity of the defect(s).

Lake Minnetonka bridges listed on the National Bridge Inventory database (information believed current. Updates will appear at the end of this post):

Orono: County Road 135

Located less than a quarter mile from the County Road 51 intersection, the Maxwell Channel Bridge was built in 1935. Spanning just under 11 meters, the two-lane bridge carries less than 1,000 vehicles on an average day and is posted for load weight restrictions.

The bridge’s foundations have been determined to be stable, and both the deck and substructure are classified as being in satisfactory condition.

However, the overall structural evaluation of the bridge found “intolerable” conditions requiring high priority corrective action.

The superstructure (or span) is deemed to be in “serious” condition. Bridge railings, transitions, approach guardrails and approach guardrail ends are also below acceptable standards, and there is no navigation control on the waterway (which is not required).

The bridge received a sufficiency rating of 29.6 on a 100-point scale and is currently classified as structurally deficient.

Deephaven: Northome Avenue

Located just over a half mile west of the County Road 5/Minnetonka Boulevard intersection, this 27.6-meter bridge was built in 1920 and bisects a pedestrian/bike trail.

The bridge carries less than 100 vehicles on an average day (according to a 1993 survey), and the deck, superstructure and substructure are classified as being in fair condition.

However, bridge railings, approach guardrails, transitions and guardrail ends do no meet acceptable standards.

The bridge received a sufficiency rating of 45.2 on a 100-point scale and is currently classified as structurally obsolete.

Orono: County Road 146

Located one mile north of the County Road 51 intersection, the Long Lake Creek Bridge was built in 1921 and is classified as a mainline roadway. The bridge stretches just less than seven meters and carries less than 1,500 vehicles on an average day.

While the deck is in satisfactory condition, the bridge’s foundations have been determined to be unstable, and both the substructure and superstructure are classified as poor. Additionally, bridge railings, transitions, approach guardrails and approach guardrail ends do not meet acceptable standards. There is no navigation control on the waterway (which is not required).

The bridge received a sufficiency rating of 49.0 on a 100-point scale and is currently classified as structurally deficient.

Excelsior: Minnetonka Boulevard

Located a half-mile north of the Hwy. 7 intersection, the St. Albans Bay Bridge was built in 1941 using concrete and spans just less than 33 meters.

The bridge carries about 4,500 vehicles on an average day (according to a 1993 survey), and the structure’s foundations have been found to be stable. The deck, superstructure and substructure are all classified as being in fair condition. It is also eligible for the National Register of Historic Places.

Bridge railings, transitions, approach guardrails and approach guardrail ends do no meet acceptable standards, although the structural evaluation found “somewhat better than minimum adequacy.”

The bridge received a sufficiency rating of 51.5 of a 100-point scale and is currently classified as being functionally obsolete. 

Orono: County Road 51

Located about a half mile west of the County Road 135 intersection, the Hendrickson Channel Bridge was built in 1959 using steel as the primary material. The bridge spans more than 36 meters and carries more than 5,000 vehicles on an average day.

The bridge’s foundations have been determined to be stable, and the span meets minimum tolerable limits.

However, the deck has been determined to be in “serious” condition. Bridge railings, transitions and approach guardrail ends are below acceptable standards, and there is no navigation control on the waterway (which is not required).

The bridge received a sufficiency rating of 55.6 on a 100-point scale and is currently classified as structurally deficient.

Wayzata: County Road 101

Located about a half mile south of the Hwy. 12 intersection, this bridge was built in 1988 and spans a BNSF rail bed.

Stretching just over 35 meters, the two-lane bridge carries more than 12,000 vehicles on an average day. Bridge railings currently meet acceptable standards, and the deck is classified as being in good condition. The superstructure has been found to be in fair condition, and the substructure is classified as being satisfactory.

Transitions, approach guardrails and approach guardrail ends, however, do not meet acceptable standards.

The bridge received a sufficiency rating of 69.3 on a 100-point scale and is currently classified as being functionally obsolete.

Orono: County Road 146

Located about a mile south of Hwy. 12 on South Brown Road and intersecting with the Luce Line Trail, this 29.5-meter, two-lane bridge was built in 1955 and averages just over 3,600

Reasons for the “structurally deficient” classification include railings not meeting acceptable standards, a poor deck and no median. The bridge’s transitions, approach guardrails and approach guardrail ends are similarly below acceptable standards.

The bridge received a sufficiency rating of 73.8 percent on a 100-point scale and is currently classified as structurally deficient.