Knowledge Resources

During the design phase of advanced parking management systems (APMS), there are a number of issues that project managers need to consider to ensure the success of their project. These include technical issues, such as the selection of an appropriate technology, and the availability of communications lines and power supplies, as well as issues related to the approval of sign appearance and location. Based on the experience of the three sites profiled in this study – Baltimore Washington International (BWI) Airport, Seattle Center, and Chicago Metra park-and-ride facilities -- the following set of lessons learned highlight key design phase issues in APMS projects.

• Integrate the APMS project into a larger regional ITS architecture. By linking the APMS project to the existing regional architecture, it may be possible to leverage existing resources, such as communications channels and traveler information media that are funded under larger regional efforts. Several of the APMS projects examined for this study suffered delays and cost overruns because of uncertainties with stand-alone communications, power, and design and placement of the signs. Linking with a regional architecture reduces the potential for technical difficulties that may delay implementation and at the same time may provide opportunities to seek Federal and state funding (i.e. funding associated with ITS based traveler information systems, congestion management, and clean air attainment programs).
• When choosing a technology, consider whether the facility is new construction or a retrofit, whether the facility is subject to frequent repaving, and whether or not the parking configuration will change over the long term. The two types of counting systems for APMS deployments include entry/exit counters and space occupancy detectors. APMS applications that employ closed systems (such as BWI Airport and Chicago Metra) use signs, space occupancy detectors, and a dedicated central computer. These systems typically use dedicated fiber optic lines to communicate between nodes. While they provide real-time, high quality information, they are expensive and usually require that the communications infrastructure be included in the facility construction. In cases where existing facilities are retrofitted with APMS, space occupancy sensors that use RF communications are a good alternative to fiber optic communications. These RF transmitters communicate between individual parking spaces and a local hub, with the local hub transmitting the information to a central computer. Entry/exit counters are another option, especially appropriate for retrofitted facilities. While entry/exit counters are not as accurate as individual space sensors, they are easier to install and operate as they do not require complex communications infrastructure.
• Consider the design requirements associated with different technologies. For example, with deployments that use entry/exit counting systems, wide driveways and narrow detection zones can lead to missed counts. Moreover, when there is significant transient traffic that shares the entrance with the parking facility, the system count refresh rate needs to be fairly high to ensure that transient or circulatory traffic is not counted against the number of available spaces.
• Research the availability of communications lines and powers supplies thoroughly and get the permit process going early; check availability in the field before committing to a design. APMS devices require access to communication channels and power supplies, and the availability of communications lines and power lines may constrain the choice of technology options. Solving connectivity issues is a major activity within the system design and installation process.
  • The Seattle APMS project experienced problems with the wireless communications between the detectors and the central computer, resulting in significant project delays. As of 2006, only the passive component of the system (providing directions to parking) was functioning. Due to technical difficulties, the active component (i.e. the provision of real-time space availability) was not operational.
  • Metra was proactive in addressing any potential issues by calling for a radio frequency field study as part of the construction bid.
• Involve those that have authority and influence in the approval of sign appearance and location early in the design process. Sign appearance and locations can become a significant source of delay and increased cost, since approval is often required by architectural control boards and historical preservation organizations. Late changes in sign appearance can jeopardize a project’s progress, as they often require redesign and re-permitting for new communications infrastructure and power access. Throughout the design process, records of approvals and changes should be kept, and a final sign design must be formally agreed upon.
  • In two of the three sites visited changes to signage in the latter part of the deployment introduced significant costs and delays.

It is important to address the design phase issues highlighted in this set of lessons learned, so that the project can proceed on schedule and within budget, and so that the benefits of the new system can be maximized. The potential benefits of APMS are many: travelers can make better informed decisions regarding their trips, and the easier access to parking results in reduced frustration and reduced time spent looking for parking. This also results in mobility benefits for the jurisdiction, as fewer patrons are circulating the street network in search of parking. In order to realize these benefits, however, the APMS must be properly designed. Difficulties during the design phase can hinder the progress of the project, and may impede efforts to improve customer satisfaction and traveler mobility.