Illinois DOT uses structural analysis software for truck permitting system

March 14, 2019
oversize/overweight permit for trucks Illinois DOT
The state of Illinois issues oversize/overweight permits for trucks carrying large loads

The Illinois DOT (IDOT) must find a safe route for trucks traveling in the state of Illinois and issue an oversize/overweight (OS/OW) permit for trucks carrying large loads. With slow, manual permitting processes, IDOT sought to update and automate its permitting system. IDOT implemented the Illinois Transportation Automated Permits (ITAP) system in 2012. The ITAP application auto-issues permits for trucks traveling on roads and highways maintained by the state of Illinois. Individuals submitting the application must enter their truck and load information, and then the application searches for a feasible route that would support the weight and size of the truck. To improve this system even further, IDOT decided to integrate Bentley’s SUPERLOAD software to optimize the weights and dimensions of the loads and evaluate the infrastructure on the chosen routes.

Bentley’s SUPERLOAD bridge analysis software was used to provide structural analysis, and the weight limit for auto-issued permits was increased to any load less than 299,999 lb. When a successful route is found within the ITAP system, all roadway structures on the route are analyzed by SUPERLOAD for the specific truck and load configurations provided. This analysis is important in determining the optimal route for OS/OW loads. The ITAP application submitted a list of these structures to the Bentley SUPERLOAD bridge analysis web service, which applies structure ratings to each structure based on the load and the structure’s characteristics. If these structures will not support the weight or are too small for the load’s measurements, another route is determined. If no failed structures are found, a permit is automatically issued.

The increase in the weights reduced the number of bridge engineers that had to manually analyze structures for permit requests at a significant savings to the state, which also reduced the time it takes to obtain a permit. By going to the current weight of 299,999 lb, IDOT saved 54,600 analyses being manually done each year. Throughout each phase of development on this project, the design team was challenged to increase the number of permits auto-issued annually by providing real-time structural analysis for sizable loads. Those seeking permits also received new map layers, providing them with more information about their route, as well as new ways to find a route. After adding Bentley SUPERLOAD software into the ITAP application system, IDOT jumped from 74% auto-issuance for OS/OW loads to 99.2% currently.

In the second phase of this project, IDOT implemented the SUPERLOAD bridge analysis software in order to analyze all the roadway structures on the route chosen by the ITAP system to determine if the infrastructure around the route can support the weight and size dimensions of the truck’s load. The software looks at bridge clearances, live-load analyses and temporary restrictions to determine the feasibility of the route. SUPERLOAD applies structure ratings to each structure based on the load’s characteristics and the structure’s features. If these structures will not support the weight or are too small for the load’s measurements, another route is determined. The state’s bridge engineers were confident with the SUPERLOAD analyses. In both phase II and phase III of this project, SUPERLOAD increased the weight of the load, ultimately landing at 299,999 lb.