Lane Assignment/Configuration Design Issues
A number of toll road operators configure one or more lanes to operate in multiple modes (i.e., some combination of attended, unattended and ETC dedicated lanes). The New York Thruway and the Orlando Orange County Expressway Authority are examples of operators who operate multiple mode lanes. These lanes allow operators to re-configure plazas for times of varying ETC demand. For example, during peak tourist periods when traffic is heavy but ETC participation rates are low the lane would operate as attended and ETC. Lane convertibility does not necessarily involve wholesale changes in modes of operation, but rather changes in the count of each lane type.
As average ETC penetration rates increase and dedicated lanes are added to serve the demand, previous throughput capacity challenges wane and the need to vary lane types to maximize vehicular throughput also diminishes. As average speeds through toll plazas increase, the need to simplify and minimize lane selection increases. This in turn results in the need to group payment types and limit the number of lane payment types.
Lane Assignment/Configuration Guideline Development
Practically, there are two configurations for ACM/ATIM lanes, depending on the need for reversible lanes and the location of ETC lanes... Illinois and OOCEA, for example, locate their cars-only ETC lanes to the far left; with ACM lanes operated in between the ETC and attended lanes. Other agencies have located the ACM lanes to the left, with ETC lanes in the center. This configuration attempts to concentrate commercial vehicles within the plaza by grouping the lane types (i.e., ETC dedicated lanes and attended lanes) that these vehicles are allowed to use. This also results in the lower operational cost ACM lanes being located in the center of a bidirectional conventional plaza, where reversible operation can be easily implemented. For all cases of low truck volumes and physically separated directional plazas, as the volume of ETC traffic increases, and the volume of ACM traffic decreases, ETC dedicated lanes should be located to the left of the plaza, and the ACM lanes should be located in the center. This arrangement supports conversion of ACM lanes to ETC dedicated lanes instead of conversion of attended lanes, a process that is likely to cost significantly less.
Existing agency design standards, and the current AASHTO or MUTCD guidelines and standards, have provided little guidance on the subject of toll plaza lane assignments and configurations.
Lane Assignment/Configuration Guidelines
Based on the survey results above, current trends in the industry and results of literature research on the subject matter, the following Lane Assignment Guidelines are provided:
|Guideline||Lane Assignment Guideline 1|
|Text||All payment type lanes should be grouped together or clustered, particularly during peak traffic periods in the case of multi-mode capability. This enables advance plaza configuration signing to enable early decision-making on lane selection.|
This provision is intended to enable driver decision making to be done in stages, first to select the payment type, then selecting a particular lane offering the selected payment type based on queue length and its vehicle composition.
|Guideline||Lane Assignment Guideline 2|
|Title||Permit or Over-Size Vehicles|
|Text||The far right lane should be sized to accept permit or oversized vehicles.|
This is consistent with common practice, and allows the slowest vehicles to stay to the right. Note that if ETC dedicated lanes are oriented to the right of the plaza, this requires permit-vehicles to pay with ETC. Provisions for oversized vehicles may not be possible at constrained plazas and the underlying facility (e.g., size, structural capacity and safety considerations), particularly for bridges and tunnels.
|Guideline||Lane Assignment Guideline 3|
|Text||Attended lanes are slower processing lanes because of truck transactions, receipt processing and informational assistance, and should be located to the right side of the conventional plaza.|
Ramp plaza lanes may need attended lanes on both the left and right sides to more safely accommodate traffic arriving from and or departing to multiple directions.
|Guideline||Lane Assignment Guideline 4|
|Text||ACM/ATIM lanes are capable of processing vehicles at a higher rate than attended lanes and should be located to the left of the attended lanes.|
|Guideline||Lane Assignment Guideline 5|
|Title||ETC Dedicated Lanes or ETC Express Lanes|
|Text||ETC dedicated lanes should be grouped or clustered and located to the left of the conventional plaza. Consideration should be given to locating dedicated lanes in the center of a ramp plaza if the plaza approach or departure receives or feeds, respectively, multiple directions of travel. Express lanes, by definition, must abut, be physically separated from the conventional plaza, and consist of at least two lanes.|
The intent is to breed familiarity by users when traveling multiple facilities.
Table of Contents | List of Tables | List of Figures | Previous Section | Next Section | HOME