top of page

Little Green “O”

Last week, this blog discussed the Little Green “X”.  The meat of the article was about bridges in Illinois that are referred to as “legal-weight” and are notated by the Illinois Department of Transportation on their online, interactive map with a little green “X”.  Like a game of structural tic-tac-toe, there are also bridges that are notated by a little green “O” (with a little “X” inside it).  These bridges are referred to as “ton-load” structures.  Whereas legal weight structures are primarily a concern for overweight permit loads, ton-load structures are a concern for all truckers.  Why?  Because failure to recognize them will cost the trucker a ton of money.

Before driving headlong into ton-load structures, some language needs to be clarified.  The terms “bridges” and “structures” are interchangeable, but it is important to remember that when discussing overweight violations for crossing weight restricted structures in this article, the term “structure” will be used.

This is to prevent confusion with overweight violations of the federal bridge formula.  Technically, they are referred to as “elevated structures” in the Illinois Vehicle Code, 625 ILCS 5/15-111(E) and (F).  These structures are not always the spans over bodies of water, highway or railroad overpasses.  Many restricted structures are simple box culverts or drainage ditches.

As listed the previous paragraph, there are two sub-sections listed.  Subsection 15-111(E) is the enforcement section that should be notated on any overweight citations.  Subsection 15-111(F) is the authority for IDOT to rate and evaluate all structures.  For reasons unknown, the Illinois General Assembly has duplicated both these subsections again in 625 ILCS 5/15-317.  However, there is no penalty section associated with 15-317, but there is with 15-111.

Another key point to understand is that local authorities cannot rate and evaluate structures on their own.  A local unit of government may request IDOT to come do an analysis, or IDOT can even choose to do a study of a local weight structure on their own.  Each structure is assigned a unique identification number and a weight rating by IDOT.  The point is all structures in Illinois, regardless of road authority, fall under the jurisdiction and oversight of IDOT.

This is for good reason.  If local authorities could evaluate, rate and post their own weight limits on structures, the end result would be an unreasonable money grab.  Uniformity would be lost.  The temptation of sordid financial gain through overweight fines would be astronomical.  The legislature has provided a way to protect the infrastructure through analysis, and IDOT is the regulatory agency assigned to do so.

When IDOT evaluates a structure that eventually becomes a ton-load, a letter is issued to the local authorities notifying them of the restriction.  This letter also lists the weight rating for the structure.  There are two ways IDOT will rate a ton-load structure…either with a flat maximum gross weight or a tiered gross weight system based on vehicle configuration.  However, IDOT does not publicly list the ton-load structure weight limits.  Unfortunately, these are learned in real time on the road by truckers.


Ton-load structures are all about gross weight.  Unlike their legal-weight cousins, there is no axle weight limit listed on a ton-load structure.  A 5-ton weight limit, for example, is fairly straight forward to understand, but a tiered ton-load structure is a little more involved.

Tiered ton-load structures list three maximum gross weights for the structure.  First, a maximum single vehicle weight gross weight.  This could be a dump truck, a cement mixer or a garbage truck. Second, it lists a maximum gross weight for three or four axle combinations (truck and trailer).  Third, it lists a maximum gross weight for five or more axle combinations (again, truck and trailer).

The problem is that the driver with a 3-axle single vehicle looks at the sign while driving and sees “3 or 4 Axle” and does not realize the sign is talking about a combination.  He then erroneously believes he is entitled to a higher weight.  To further confuse the issue, some tiered ton-load structures use small pictures of trucks on the sign instead of listing the info with text.

What happens when the driver crosses the structure, is found to be overweight, and levied a fine?  That little green “O” usually turns into a verbal “Oh” followed by a choice expletive.

18 views0 comments

Recent Posts

See All


bottom of page