December 2, 1997

The New York City Department of Transportation (DOT) recently completed the Park Drives Alternate Use Study. The study examined several traffic-reduction options for Prospect Park including Scenario 2- Close all roadways. Other scenarios proposed a combination of partial park closures to motor vehicles like instituting year-round weekend closing hours and closing selected entrances and exits. Before public release of the study, DOT stated implementation Scenario 2 would not be feasible due to "unmitigable impacts" (at one intersection during the PM peak period). DOT made this decision based on a flawed study with faulty assumptions. Transportation Alternatives found the study flawed to due the absence of any shrinkage calculations and the lack of true cost accounting.

Background

Prospect Park is Brooklyn's greatest jewel, the largest park in the borough, serving nearly one million people per year. It is a wonderful oasis from noise, tumult and the hectic pace of streets. It is ideal for running, walking, cycling, skating and playing. Park designers Frederick Law Omlstead and Calvert Vaux considered Prospect Park to be a better example of their work than its sister, Central Park in Manhattan. Planned in the late 1800s, long before the arrival of the automobile, its design accommodates pedestrians, bicycles and carriages in a smooth circulation pattern. Unfortunately, today's automobile traffic makes the park loop a dangerous and hostile place. Dr. Rachel Fruchter's death last July while cycling in the park illustrates this precarious condition very much.

Nearly twenty-five years ago, public agitation resulted in weekend and midday closing of the park. In the late 1980s, increased traffic volumes in Brooklyn coupled with greater recreational use of the Park led to more appeals for a completely auto-free Prospect Park. Public pressure in the early 1990's was the catalyst behind DOT's Prospect Park Drives Alternatives Use Study. The study, first announced in 1993, was not completed until late 1997. During the interim, public support expanded, culminating in the summer of 1997 with some 4000 postcards delivered to Brooklyn Borough President Howard Golden in favor of a car-free Prospect Park.

Interpretation of Scenario 2 Data

DOT studied 15 intersections and three circles surrounding Prospect Park during both AM and PM peak hours. DOT says that in the AM and PM peak periods three intersection approaches will become level of service "F" -- meaning that waiting cars would be unable to clear that intersection in a single traffic-signal cycle-- should the park drive be entirely shut to traffic. The projected AM peak hour impacts at three locations can be mitigated by traffic-signal retiming and two of the locations can be mitigated during PM peak hour. The intersection of Prospect Park Southwest at Park Circle cannot be fully mitigated by traffic-signal retiming, says DOT. Mitigation of this intersection would require major capital improvements not discussed in the study. Simply put, one intersection, for one hour, prevents implementation of Scenario 2. DOT arrives at the decision rooted in a facile analysis of traffic consequences with no attention paid to myriad benefits associated with the Park closure.

Flawed Assumptions -- Shrinkage

For its study, DOT assumed that all motor vehicles presently using Prospect Park Drive would continue to enter the study after the park was closed. In contrast the DOT's 1992 Central Park Study assumed that 15% of motorists would stop entering the study area.

"It is assumed that this 15% would divert either to routes outside of the study are, shift to hours of travel during non-peak periods or change to transit or other non-auto modes." [DOT, Central Park Drives Alternate Use Study- Technical Memorandum # 4, 1994.]

Had DOT used a 15% shrinkage rate, the intersection in question, Park Circle and Prospect Park SW would have a lower southbound volume (1950 rather than 2294) during the PM peak period.

Additionally, the DOT study calls for changing the signal timing at that intersection, from 3-phases to 2-phases with closure of the park. The signal change would result in a shorter queuing period or increased capacity at that intersection. The reduced volume combined with the adjusted signal timing means there would be no increase in congestion at Park Circle and Prospect Park SW.due to park closure.

Moreover, DOT's traffic diversion assignment of Prospect Park traffic to adjacent the street network is extremely simplistic and unrealistic. This methodology only stirs controversy in surrounding communities by concluding that cars displaced from the park drive will result in congestion on neighborhood streets. This simply is not the case. Assuming traffic shrinkage rate of 15%, closing Prospect Park Drives would result in a decrease in overall traffic flow within the study area.

No Benefits Discussed

Clearly, eliminating traffic in the park will greatly improve the walking and cycling environment. This benefit is not limited to the Park, but includes surrounding intersections. In the study, the accident analysis shows every entrance and exit to the park as a high accident location. Undoubtedly this situation stems from road geometry (traffic circles and merger of three or more roads) ill-equipped to handle high traffic volumes. Park closure would result in safer approaches for pedestrians and cyclists especially at Grand Army Plaza where crossing is treacherous and cumbersome.

Additionally, in setting up its car-free park scenario, DOT did not reduce traffic in many intersections surrounding the park even though closing the park would clearly have that effect. All the intersections leading to the park show no decrease in traffic (for example Grand Army Plaza and Vanderbilt, 3rd Ave and Prospect Park West). Even using DOT 0% shrinkage scheme, Grand Army Plaza would experience a significant reduction in traffic with closure of the park's major entrance and exit.

DOT also ignored further traffic benefits. The intersection of Flatbush Avenue and Atlantic Ave is not studied. According to the study the majority of motorists enter the park at Park Circle, exit at Grand Army Plaza and continue to travel north on Flatbush Ave to the Manhattan Bridge. Since no cars will becoming out of Prospect Park on to Flatbush Avenue, it is probable that traffic flow in this critical -- and highly congested intersection would improve with a Prospect Park closing.

Conclusion

DOT's worst-case diversion of Prospect Park traffic to adjacent roads generated a study devoid of the true traffic consequences associated with the park closure. It is a futile attempt by DOT to sway public sentiment against a car-free Prospect Park. An actual trial closing of the Prospect Park Drives is the logical next step in evaluating the proposal.