In the current climate of limited transportation funding combined with rapid advances in tolling technology, it has become increasingly important for transportation agencies to consider future toll system expansion as a major component of toll facility design. Within the state of Texas, transportation agencies have responded to funding limitations by phasing toll projects into interim and ultimate conditions. The interim condition of the project is designed to meet current travel demand while still adhering to budget constraints. The ultimate condition, which undergoes expansion, meets the increased demand when additional funding becomes available. Additionally, advances in technology and increasing demand require the continuous update, replacement, and addition of new tolling equipment even on projects that are not phased. Designing tolling infrastructure to allow for future expansion can ease the incorporation of new technology into existing toll facilities in the future.
Following the success of recently implemented express lane projects, the Florida Department of Transportation formed a joint study group with Miami-Dade Expressway and Florida Turnpike to develop a Regional Concept for Transportation Operations (RCTO). This study, the Southeast Florida Express Lanes Regional Concept for Transportation Operation, covered a wide array of concepts, including physical design.
The RCTO report found that during the design phase of a project, it is important to design tolls to withstand the load of future requirement and equipment loads. Also, gantries should be designed with sufficient space to accommodate additional equipment, including cameras and automated vehicle detection equipment. Conduit size requirements should be designed to allow for future needs such as for deploying this additional equipment, according to the final report.
Further consideration should be given to the various types of toll gantries to be implemented on the project. Monotube toll gantries can be design to accommodate additional loads, and allow for varied equipment spacing along the width of the travel lane. Longitudinal spacing along the direction of travel, however, is set at the time of construction and cannot be changed.
At the other end of the spectrum is the fully customizable space frame. Equipment can be mounted at various spaces both across the width of the travel lane, as well longitudinally along the direction of travel.
Tolling and transportation agencies can further accommodate future toll systems expansion through their design manuals and procurement documents. Updating design requirements to allow for additional loading and equipment can prevent undo throwaway costs associated with reconstruction. Incorporating similar requirements into procurement documents will ensure that agencies can accommodate future expansion while still giving the proposer the leeway to select the most cost-effective structures.