Combined Transit and Freeway Real-Time Information for Smarter Modal Choices

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1 Combined Transit and Freeway Real-Time Information for Smarter Modal Choices Joerg Nu Rosenbohm Rockville, MD Dan van Kley Suwanee, GA Bryan Mulligan Suwanee, GA Transit Commuter Information System Project Overview Intelligent Transportation Systems are evolving and new innovative ideas are changing the way we look at transportation and modal choices. This paper considers the deployment of a Transit Commuter Information System (TCIS) and a Real Time Signs (RTS) system by the Metropolitan Council of Minneapolis and St. Paul, Minnesota and the potential impact of this project to shape the behavior of commuters and increase transit ridership. The objective of the project is to influence the behavioral pattern of commuters by providing them with information about viable commuting alternatives that could move drivers away from driving single-occupancy vehicles on the freeway towards using transit. The Metropolitan Council s goal is to increase ridership on transit by up to five percent. The TCIS system provides commuters with travel time information for both vehicle and bus transit, parking availability at park and ride lots, and next bus departure times. The RTS system provides dynamically updated AVL-based bus arrival times for all bus routes at a given stop. In short, the project is based on a belief that a significant number of commuters avoid transit because of: Personal experience attempting to park at a Park and Ride lot and finding no spaces available. Such an experience drives commuters to avoid using the Park and Ride system. A lack of real-time information about bus scheduling and next bus departure times. Uncertainty about the potential time savings from using transit. Commuters are unsure if they would save time by using transit. In order to encourage commuters to use transit, a system of more than 70 DMS displays has been installed around the Twin Cities metropolitan area to provide commuters the data they need to make informed decisions about using transit. Functional Summary The following information is presented to motorists in detail on Dynamic Message Signs: 1. Comparative point-to-point car travel vs. bus travel times are displayed on signs located prior to the park and ride parking lots to provide drivers with accurate and up to date information on the time savings available from using transit. Figure 1: Comparative Travel Time DMS 2. Current time until the next bus departure at the relevant Park and Ride lot so that the motorist may determine in advance if they will be able to make their intended transit bus before exiting the freeway. 1

2 3. Parking space availability in the relevant Park & Ride lot, so the driver will know that there is available parking before exiting the freeway. Project Scope The following features are included in the TCIS and RTS systems: An integrated, GUI-based central control system has been deployed to provide oversight and control of every element of the TCIS and RTS systems. Dynamic Message Sign (DMS) control Full NTCIP-compliant control of over 70 DMS signs Park and Ride Availability System (PRSAS) NTCIP compliant interface and control of inductive loop parking lot occupancy counters at 4 transit Park and Ride lots. Figure 2: Parking Space Availability DMS 4. Once at the bus transit station, detailed bus route and real time bus departure time information is provided. Transit Commuter Information System Display Display of any or all of four data classes (location of parking availability, number of available spaces, next bus departure time, bus and car point-to-point travel times) in any combination on DMS signs. Real Time Signs Display Display of up to 48 bus routes with dynamically updated arrival times based on bus AVL data. WYSIWYG GUI Map View Pixel-by-pixel rendering of RTS messages and integration of TCIS static sign elements into the live user interface Map View. Figure 3: Bus Departure Information DMS 2

3 System Structure Figure 4: System Structure The diagram above gives a visual illustration of the system. Lines and type in black denote devices and infrastructure while lines and type in green denote the system s data flow. For the purposes of the diagram, system data flows left to right while the commuter s path through the system is right to left. The system s data flow is described below, corresponding with the red numerical identifiers. 1. The primary data source for the TCIS system is the inductive loop vehicle counting subsystem. This system uses pairs of standard inductive loops at each parking lot entry/exit point to determine any given vehicle s direction of travel into or out of the lot, regardless of the lane s designated direction. After being calibrated with the lot s current occupancy, the system can then keep a running count of the number of available spaces in the lot at any given time. All calculations and communications are performed by an embedded microcontroller card. This card is referred to as a PCC, or Pool Count Controller. 2. Each Park and Ride lot is connected to the main Metro Transit server facility via frame relay. The central control subsystem uses this link to communicate with the vehicle counting subsystem by means of an Ethernet/IP-based network using SP-Ethernet, an NTCIP standard center-to-field communication method. 3. The Metro Transit travel time server provides an interface to the external system that determines car and bus travel times and bus departure times. This third party system determines car and bus travel times from roadway VDS systems and bus departure times from a GPS-based AVL system. The travel time server is located on the same local network as the central subsystem server and uses standard web service communication methods to send data to the central subsystem server. 4. The central control subsystem is the main component of the TCIS system. It is the interface between the data from the AVL travel time and parking availability systems and the DMS signs displaying the information to the public. It 3

4 provides definition and customization of DMS messages, monitoring of travel time and parking availability data flows, and system diagnostics. This is the only system element that system operators interface with regularly. 5. The RADIUS wireless network interface provides a secure authenticated channel from the Metro Transit network to the cellular service provider s network to ensure the integrity and security of the data being sent across the cellular network. 6. All DMS sign controllers are NTCIP 1203 compliant. Cellular data modems are used for most signs because of the signs distance from any other available communications infrastructure. Messages are transmitted to the signs via NTCIP standard center-to-field communications methods. Additional Features The following are additional features in the system: Auto calibration: the vehicle counting system provides an internal automatic calibration mechanism that can be configured from central. It allows the operator to specify a time of day with a known occupancy (for instance, empty at 2 AM) and calibrates the current availability count accordingly. This helps offset any systemic counting errors. Bi-directional counters: using two loops for each entry/exit lane allows the system to detect vehicles traveling in either direction and adjust the lot availability accordingly. This avoids errors due to vehicles traveling the wrong direction in a lane. Multiple pools per lot: the vehicle counting system allows for multiple pools (groups of parking spaces) to be configured per lot facility. Each pool must be entirely bordered by counters to ensure all traffic in and out is counted. Each pool has its own set of counts and statistics and can be displayed separately on DMS signs. Qualitative and quantitative display: the central control system can be configured to display qualitative messages (such as FULL or NOT FULL ) based on space availability thresholds for each lot. It can also display quantitative messages (the exact number of spaces available in a lot, such as 243 spaces ) in any part of a message. Data display flexibility: DMS messages on TCIS signs are fully configurable for each external data type (parking availability, travel times, bus departure time), which allows messages with any combination of data to be displayed as desired. Message overrides: the central control system provides a facility to permanently or temporarily override the automated messages on a TCIS or RTS sign with a user generated manual override message based on the relative priorities of the automated and manual messages, and revert to automatic messages after a specified interval. RTS signs also provide a feature to only override the last line of a sign to allow extra information to be displayed without compromising normal function. Project Results Performance Measurements Currently, full performance measure studies have not yet been performed on the system. However, testing performed thus far by Metro Transit and their appointed representatives produced the following results: An average of 98.3% accuracy in counting vehicles entering and exiting a parking lot. The 1.7% inaccuracy is thought to likely be due to a temporary communications failure. A maximum lag time of 1 minute for data propagation through the entire TCIS system. This was measured by displaying quantitative information on a DMS sign at a parking facility (i.e. 243 spaces available ), driving a vehicle over an entrance or an exit, and measuring the time between the vehicle s entry/exit and the update of the sign. In all cases this update time was less than 1 minute, and less in many cases. Challenges and Lessons Learned The following are challenges and lessons learned from the project: Counting accuracy: the primary challenge of any parking availability system is achieving a high level of accuracy. In the case of an inductive loop counting system, this is most often due to less than ideal loop placement or insufficient lane delineation. Loops that are placed in areas where stop and go traffic is frequent can experience trouble with accuracy because vehicles do not cross from one loop to another within the system threshold for a count timeout. Positioning loops in lanes that are open and allow vehicles to cut laterally across adjacent lanes can cause vehicles to miss loops in a 4

5 counter and/or trigger adjacent loops, which will cause inaccuracy. In the Metro Transit system, the Burnsville Park and Ride facility was a major example of this. The Burnsville facility has large entrances and exits that are not well delineated, which led to some accuracy issues. These were dealt with mostly with regular calibration and reconfiguring loops in trouble areas to only count in a single direction. A higher level of accuracy could be achieved by placing individual parking space occupancy detectors in each parking bay, albeit this would increase the investments. Cell modems: due to their relatively remote location, most of the TCIS DMS signs used cellular modems for central to field communications. This led to increased lag in data transmission and occasional communication failure. The cellular modems also experienced an unexpectedly high number of hardware failures, the causes of which are still uncertain. This issue was dealt with by configuring the NTCIP default messages for each sign to ensure that appropriate messages were activated if a given sign lost communications for an extended period. Message length: most DMS signs are used for roadway ITS projects, which generally consist of relatively short messages. The RTS system uses signs that can contain up to 7 pages of 8 line messages with dense text and many formatting tags. This led to some challenges in the effective transmission of these large messages, as well as maintaining reliable display during periods of high network utilization. Future Plans At present, only 4 of the roughly 100 Metro Transit Park and Ride lots have the TCIS system deployed. Due to the level of federal funding for the project, further federal studies on the effectiveness of the system must be performed before the expansion of the system will be authorized. Upon the completion of these studies, it is anticipated that the TCIS system will be deployed to the remainder of the Metro Transit Park and Ride lots. Success of the federal studies may also lead other municipalities and DOTs to follow suit and deploy their own similar systems. 5