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Case 11: Tampa Expressway

History:  During the past 20 years, continued population growth and ever increasing traffic resulted in severe congestion for thousands of daily Expressway commuters.  The journey at peak times to commute a 10 mile stretch of Expressway from downtown Tampa to Brandon was as much as 40 minutes.  A resolution to this congestion was needed.

Building a new green field project or acquiring land was not an option due to environmental issues.  So the Tampa Hillsborough Expressway Authority’s extraordinary solution to relieve this severe peak-hour congestion and improve access was to build 10 miles of reversible express toll lanes between Interstate 75 and downtown Tampa.  Most of the project was constructed as an elegant segmental bridge and was built using only six feet of space within the existing Expressway median.  The aim of the project design was to  dramatically reduce impacts on the community and environment, as well as a few cost savings on the way! 

Background:  The Reversible Express Lanes design stemmed from the results of comprehensive surveys to determine the behavioural pattern of Expressway users, where they went, how they got there and when they travelled.  The Expressway Authority received over 2,800 returns from these surveys forming a clear picture of  commuter behaviour.  The results told that 10 lanes of capacity were required at peak times to cover the road users needs.  However, 10 lanes weren't needed in both directions, due to the nature of exiting traffic and their time of travel.  This led to the concept of reversible lanes - a non-stop Expressway from Brandon to downtown Tampa.

Project Detail:  The resulting project was a technological innovation which included the first reversible cashless three-lane open road tolling system, a unique approach to video toll collection and a centralised Traffic Management Centre (TMC).

How it works:  Utilising ORT with no toll booths or plazas eliminates the risks associated with large volumes of traffic slowing down to pay the toll.  However, for an ORT system to meet its accuracy levels the AVC aspect becomes a critical function within the bigger picture.  Although the physical hardware was a standard Idris AT600 tolling installation requirement, developing the reversible ability of the software took some deliberation in the software code department. 

Although two sets of hardware weren't required, two software configuration files were a necessity, one for forward direction and one for reverse.  So tweaks were made to enable the software to shut down and restart in reverse mode.  Rules for how Idris reported or responded was another aspect requiring consideration as well as what was actually reported.  As an example, in a standard Idris configuration Idris knows the direction of travel a vehicle is moving in, should the direction be in reverse Idris reports this fact as an alarm.  However, for Tampa Idris had to determine which direction a vehicle was travelling – forward or reverse, and whether it was the correct direction for the time of day!  Once the configuration of rule files and software code was achieved the remainder of the installation was a straight forward build.

There is a time element in all this too, as the purpose of the Expressway is to keep traffic moving. Long periods of lane closure for reversing the lanes would have defeated the objective.  This was where using Idris as the AVC provided not only accuracy but time savings too.  The whole Expressway is re-set and restarted in reverse mode – it's a 'reboot' of the system! 

Overall it takes just 30 minutes to complete a change of direction.  The physical change can actually be done in 15 minutes, but the extra time is taken for the traffic engineer to drive the route and visually check and recheck everything is clear and OK.  This means there is no hardware change over, the process is carried out remotely from the TMC and that enables the Expressway to be operational for about 23hrs a day. 

Results: The design approach for the Tampa Hillsborough Expressway saved huge amounts in capital costs due to the technologies incorporated and the structure and design features used.  In addition, by not building interchanges and using slip ramps for access to the new reversible lanes from the old expressway, construction costs were greatly reduced.  The reversible lanes are a long term solution to traffic congestion.  The design features provide the ability to control the traffic entering and exiting the Expressway preventing volume saturation.  Prior to opening it was estimated 12,000 people would pay to use the facility at a $1 per time, the actual cost in 2007 was $1.50 and the Expressway had over 16,000 daily commuters. The traffic- carrying capacity of the existing Selmon Crosstown Expressway was increased by 150% by the new build and has completely eliminated congestion during peak hours.  A journey which took up to 40 mins now takes just 10 mins, and this project has succeeded in sustaining the vitality of Tampa city centre and improving the quality of life for its commuters.

The Idris Technology is protected by one or more of the following patents:
EP0879457, USA 6345228, 6483443 and 6337640
Registered Patents also include but not limited to European Countries, Brazil, Mexico, Canada & Australia.
Idris® is a registered trademark of Diamond Consulting Services Ltd. 

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