There are two common types of bridge posting: vertical clearance and weight. Both postings require signs on or at the bridge, and advanced warning signs.
Vertical Clearance Posting
When the clearance over a roadway is less than 14'6", state law (Title 29-A, Section 2380) requires that vertical clearance signs be installed. These signs are usually required for overpasses and for trusses with overhead obstructions. The law requires that the responsibility for installing and maintaining signs on roadways that have restrictions be placed on the custodian of that roadway. Although MaineDOT generally installs clearance signs on our bridges over town ways such as the Interstate, the municipality is still responsible according to this law. The most frequently unsigned or partially signed structures are those owned by the railroad over town ways. Note that installing signs on someone else's bridge requires permission. Measurements should be taken periodically, to ensure that the stated height is still provided.
Title 29-A, Section 2387 provides the authorization for weight posting of bridges that cannot support legally loaded vehicles. Weight posting must be based on the recommendations of MaineDOT or a registered professional engineer. Temporary weight restrictions or closure by the municipality when a structural problem occurs (i.e., a failed or weakened component) is allowed under this law until repairs or re-evaluation by a professional engineer can occur.
Protection Against Liability
Besides protecting public safety and the public's investment in bridge structures, posting helps protect against liability. Should an accident occur because of a deficiency in a bridge, Maine law may allow damage recoveries of up to $400,000 for gross negligence. In addition to any potential liability, the FHWA may withhold federal highway funds for all projects in any municipality that does not have the bridge's weight properly posted.
Signing of bridges for weight or height limitations should be done in accordance with the latest version of the Manual for Uniform Traffic Control Devices (MUTCD), Section 6F.10 of the 2009 edition. Note that a sign must be placed in advance of the bridge to allow turning around or avoiding the bridge by using an alternate route.
Responsibility for Posting or Closure
- MaineDOT- Maintained Structures: The Department has sole responsibility and authority to determine whether the structure must be posted or closed, except that a municipality may close the structure in cases of emergency. If the municipality becomes aware of deficiencies in a structure that could impact posting or closure decisions, the municipality shall promptly notify the Department. The Department is responsible for all costs and expenses related to the posting and closure, including any needed notifications, procedures, signing, and barricades.
- Municipally- Maintained Structures: The Department shall advise the municipality of its inspection findings, noted deficiencies and recommendations regarding posting or closure. The municipality has sole responsibility and authority to determine whether a structure must be posted or closed, except that the Department may close the structure in cases of emergency or when the Department reasonably determines closure is necessary to protect the traveling public from imminent hazard. If the Department becomes aware of deficiencies in a structure that could impact posting or closure decisions, the Department shall promptly notify the municipality. The municipality is responsible for all costs and expenses related to the posting and closure, including any needed notifications, procedures, signing, and barricades.