As part of the process, the Northwest Corridor Project EIS must evaluate a set of alternatives and their associated impacts in order to reach a consensus on a Locally Preferred Alternative.  Based on realization of the financial realities of the State resources that can be dedicated to the Project and comments from the Project stakeholders after the DEIS was published, the proposed project has changed considerably. Truck only lanes have been eliminated along with the Bus Rapid Transit system and its supporting facilities.  However, trucks can operate in the general purpose lanes as they do today and the CCT and GRTA Express Bus systems will be allowed to operate in the revised managed lane system to preserve the approach to provide alternative modes of transportation of the corridors.

It is intuitively obvious that if there is a large percentage of the traffic on the I-75 and I-575 corridors is concentrated in the peak travel direction in the mornings and afternoons, then a reversible system may be the correct answer to the drastic cost reduction required in these difficult economic times.  Given the directionality of the traffic, based on the new ARC 20-County travel demand forecasting model, it was determined that reversible systems should indeed be reconsidered.  This is a significant change from the results of the previous ARC model used in the DEIS which indicated no such well-defined directionality.  Several possibilities are being investigated.

The refined alternatives based on a reduced footprint currently under consideration are:

  • No-Build Alternative: This alternative depicts what would happen if the project is not built.  It also serves as a comparative baseline for the evaluation of impacts.
  • Concept A This is the refined system that results from the elimination of the truck only lanes and BRT system originally proposed.  It would be a facility with two lanes in each direction in the heart of the system on I-75 from I-285 to I-575.  North of the I-75/I-575 Interchange the alternative will consist of one managed lane in each direction in the median on both I-75 and I-575.
  • Concept B-1 This system would provide two reversible managed lanes on I-75 between I-285 and I-575.  North of the I-75/I-575 Interchange, one managed lane would be provided on both I-75 and I-575.  The Managed Lane Interchanges on I-75 and I-575 would be reduced to seven and five respectively.
  • Concept B-2 This system would also provide two reversible managed lanes on I-75 between I-285 and I-575.  However, north of the I-75/I-575 Interchange one managed lane would be provided on both I-75 and I-575 but the managed lane Interchanges on I-575 would be replaced by a system of slip ramps to provide access to and from the managed lane in the median.  Three access points would be provided in each direction on I-575.
  • Concept C This system would provide three reversible managed lanes on I-75 between I-285 and I-575.  North of the I-75/I-575 Interchange one managed lane would be provided on I-75 and on I-575 two managed lanes would be provided from I-75 to Big Shanty Road and one managed lane from Big Shanty Road to Sixes Road.  The Managed Lane Interchanges on I-75 and I-575 would remain essentially the same as the system proposed in the DEIS.

It is important to note that the managed lane traffic is barrier separated from the general purpose lanes in all cases.  With barrier separated systems proposed and limited managed lane access points, incident management is an important consideration from a safety perspective.  In addition, effective incident management can improve overall corridor performance with respect to mobility and congestion mitigation.

Managed Lanes

As part of the four alternatives under evaluation, the project will require tolling options for the managed lanes for financial viability.  There are several variations of High Occupancy Toll (HOT) lanes that are being explored, including varying occupancy requirements with congestion-pricing options.  Additionally, stated preference surveys are being used to determine prevailing opinions of these options in the affected area. 

The primary purpose of any pricing alternative is focused on effective congestion management in the managed lanes as well as revenue generation. Use of the revenues will help leverage other benefits, including but not limited to supplementing highway capital costs, operating and maintaining the facilities, customer service, etc.  The tolls will be utilized as a means to manage the number of users utilizing the facility at certain times of the day, thereby continually providing a high level of service in the managed lanes.  The price of the toll will vary by the congestion level of the roadway. For example, the toll would be higher at peak rush hour times than at off-peak times.

It is envisioned that tolls for both the managed lanes would be collected electronically without the use of toll booths; however, specific details of tolling technology have not been determined at this time.  

For more information and examples of managed lane, barrier separated systems and tolling options, please here.

Revised 01/14/2010