480 Herald Drive Ambler, Pennsylvania 19002
215-793-4177 FAX 215-793-4179

June 8, 2000

Kevin Smith
Venice Island Opposition
293 Hermitage Street Philadelphia, PA 19127

RE: Venice Island Residential Development
. . . . Manayunk Neighborhood, City of Philadelphia, PA

Dear Mr. Smith:

In accordance with your request, I have completed a review of the potential traffic impact of development of three proposed residential developments on Venice Island in the Manayunk Neighborhood of the City of Philadelphia. It is my understanding that the three proposed residential developments include the Realen Development (270 DU) the Dranoff Development (160 DU), and the Neducsin Development (88 DU). The Realen Development would take access via the Cotton Street Bridge across the Manayunk Canal, while the Dranoff Development and the Neducsin Development would take access via the Flat Rock Bridge across the Manayunk Canal.

To conduct this review, you provided certain documentation for my use including:

  • a copy of your testimony, dated March 13, 2000 before the Zoning Board;
  • a series of photographs taken on the approach and circulation roads that serve Venice Island, including a photograph of parking lot flooding on the island during Hurricane Floyd;
  • a copy of Automatic Traffic Recorder (ATR) count data taken at various locations in June, 1996 by TriState Traffic Data, Inc.;
  • a copy of a peak period (7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM) traffic count of the intersection approaches at Main Street and Cotton Street taken on January 4, 2000 by Boles, Smyth Associates, Inc.;
  • "Summary of Climatological and Hydrological Records for the Venice Island area on the Schuylkill River", prepared by G.C. Henricksen, Jr., Consulting Meteorologist, dated February 2000;
  • Area Map and Flood Map - Venice Island;
  • A copy of a letter addressed to Michael A. Nutter, Councilman - 4th District from Carole A. Blessing, Human Resource Manager of Smurfit-Stone, dated January 13, 2000 concerning safety and congestion across the Flat Rock Bridge;
  • Draft Findings of the Opinion Survey of Manayunk Residents, dated February 1998, prepared by the Philadelphia City Planning Commission;
  • Summary Report for the Traffic and Parking Study related to the Manayunk Area: Philadelphia. PA, prepared for the PIDC/Philadelphia Industrial Development Corporation by Boles, Smyth Associates, Inc., dated April 1997;
  • "Findings of Fact and Conclusions of Law of the Zoning Hearing Board of Adjustment" in the case of Trafalgar Associates v. Zoning Hearing Board of Adjustment of the City of Philadelphia, the City of Philadelphia, New Manayunk Corporation t/a Manayunk Development Corporation, Manayunk Neighborhood Council, Friends of the Manayunk Canal, and Darlene Messina, July Term, 1997
  • a series of additional photographs taken on the Green Lane Bridge, along Main Street and along Flat Rock Road including the Flat Rock Bridge showing traffic congestion and effects of overflow parking, taken on the evening of May 5, 2000 coincident with the Cinco de Mayo special event held at the Arroyo Grill on Venice Island;

Unfortunately, what is lacking from the documentation is an analysis of the specific traffic impacts that will be caused by development of the three proposed residential projects on Venice Island. A Traffic Impact Analysis is a document that is typically prepared for and funded by an Applicant for a rezoning request of the size and magnitude proposed by each of the three residential developments proposed on Venice Island. The purpose of the Traffic Impact Analysis is to compare the traffic generation of the rezoning request relative to by-right development of the site, and to examine the traffic impact of the proposed development on the surrounding streets and intersections.

To my knowledge, this analysis has not been prepared for any of the three residential projects proposed on Venice Island. The Summary Report for the Traffic and Parking Study related to the Manayunk Area Philadelphia. PA, is a valuable tool for general transportation planning of the area, but it is outdated in terms of the data that could be reused in a Traffic Impact Analysis for the proposed developments, and does not address the specific traffic impacts or site access requirements for the three developments proposed on Venice Island.

A Traffic Impact Analysis (TIA) should be prepared individually for each of the three proposed developments. The TIA's should be prepared by a licensed engineer with experience in Traffic Engineering, and should be funded individually by each of the rezoning applicant. Alternatively, a single TIA can be prepared jointly for the proposed developments, so long as the individual traffic impacts and site access requirements of each of the developments is specified in the report.

A TIA will typically include the following components:

  • General Site Description - The site description should include the size, location, type of land use, and anticipated completion date of the proposed land development. A briefdescription of other major existing and proposed land uses within the study area should, also be provided.
  • Transportation Facilities Description - The description should contain documentation of the internal and surrounding external transportation system. This should include a description of all points of ingress and egress; a description of the roads and intersections in the vicinity of the site including road widths, parking conditions, and pedestrian circulation elements; an inventory of traffic control devices such as traffic control signal, STOP signs, posted speed limits and other regulatory information; availability of public transportation service; and a description and timetable for any programmed transportation improvements in the study area.
  • Existing Traffic Conditions - Existing traffic volumes, no more than two years old should be recorded. This will include average daily traffic volumes on selected road, links, and peak period intersection turning movement volumes at major intersections affected by the project. A volume/capacity analysis should be performed to determine, levels of service for peak hour traffic conditions, in accordance with the procedures outlined in the Highway Capacity Manuals. This analysis will determine the adequacy of the existing roadway system to serve the current traffic demand.

    For the developments proposed, the TIA should present an analysis of the following intersections:

    • Main Street/Leverington Street
    • Leverington Street/Umbria Street
    • Main Street/Green Lane
    • Main Street/Cotton Street
    • Main Street/Shurs Lane

  • Development Generated Traffic - The volume of traffic generated by the proposed, development(s) should be estimated on a daily basis and for the critical peak hours for the proposed development(s). For residential development, the peak hours are typically coincident with the weekday commuter rush hours. Trip generation rates are typically calculated from the publication entitled Trip Generations . All turning movements are then calculated for the new trip generation and assigned to the access locations and to the surrounding streets and intersections. Since this is a rezoning request rather than by-right development, a trip generation calculation should also be made for the existing use of the site, or for a potential by-right development of the site. This will determine (the net change in trip generation resulting from the rezoning request.
  • For your information, a have calculated the potential trip generation characteristics for ,the three proposed Venice Island residential developments. Table I attached summarizes the results of my calculations. As indicated, the three developments combined could generate about 3,000 to 3,500 trips per day (total inbound an outbound), with peak hour traffic generation of about 230 to 270 trips per hour during the morning peak hour, and 280 to 340 trips per hour during the afternoon peak hour). It should be noted that these volumes may be reduced somewhat due to the availability of public transportation.

(l) "Highway Capacity Manual", Special Report 209, Transportation Research. Board, Washington, D. C., Latest Edition..

(2) Trip Generation. Sixth Edition, institute of Transportation Engineers, Washington, D.C., 1997.







Morning Peak Hour
In . . . Out . . . Total
Afternoon Peak Hour
In . . . Out . . . Total
Realen Development (270 DU)(2) 1,510 - 1,1750 19-22 93-115 112-137 94-110 . 46- 55 . 140-165
Dranoff Development (160 DU)(2) 970 - 1,100 12-13 . 62-70 . 74-83 61-71 . 30- 34 . 91-105
Neducsin Development (88 DU)(2) 570 - 660 8 . 38- 39 . 46- 47 37- 44 . 18- 22 . 55- 66
Total (518 DU) 3,060 - 3,510 39-43 193-224 232-267 192-225 94-111 286-336

(1) Trio Generation, 6th Edition, Institute of .Transportation Engineers, .Washington, D. C, !997.

(2) Trips per occupied dwelling unit (DU)

Design Year Base Traffic Conditions - Existing peak hour traffic volumes should be projected to the anticipated completion date of the proposed development(s). This should include a combination of background traffic growth as well as the specific traffic generation characteristics of other nearby development proposals. Background traffic growth is usually based on historical traffic growth patterns on the surrounding streets A second volume/capacity analysis is then completed for future peak hour traffic conditions without development and levels of service are quantified to determine the adequacy of the streets and intersections in the study area to accommodate future traffic even with no development of the site. For comparison purposes, an analysis of future peak hour traffic conditions with a by-right development of the site(s) can also be considered in examining the impacts of a rezoning request.

Design Year Traffic After Development - The assignment of new traffic generated by the proposed new development(s) are added to design year base peak hour traffic volumes. A third volume/capacity analysis is then completed for future peak hour traffic conditions after development of the proposed residential development(s), and levels of service are quantified to determine the adequacy of the streets and intersections in the study area to accommodate future traffic after development of the site, and to assess the need to construct improvements to accommodate the increase in traffic volume generated by the proposed new development(s). This analysis will also result in a determination of requirements to facilitate safe and efficient ingress and egress at site access points.

Conclusions and Recommendations - A listing of recommended improvements should include, but not be limited to, the following elements; internal circulation design, site access location and design, external street and intersection design and improvements, traffic signal improvements including coordination of signalized intersections along corridor, and transit design improvements. The conclusions and recommendations should be documented in a report that will also include a copy of all data collected, documentation of the various assumptions used in the analysis, a copy of all volume/capacity analysis worksheets, and any other information used in the formulation of the results and findings of the study.

The discussion presented above outlines the steps taken in preparing a typical TIA for rezoning requests and new land development proposals. In addition to determining the typical traffic impacts associated with new land development, the TIA must also address particular concerns relative to access to an island with very limited access. Specifically, emergency access and evacuation procedures must be addressed.

As described previously, The Realen Development would take access via the Cotton Street, Bridge across the Manayunk Canal, while the Dranoff Development and the Neducsin Development would take access via the Flat Rock Bridge across the Manayunk Canal. The Cotton Street access to Venice Island also crosses an at-grade railroad track. As I understand it, there is no discussion to construct additional access to the island, or to construct a street on Venice Island to connect the two existing bridges across the Manayunk Canal or, alternatively to construct ramps to the Green Lane Bridge. These developments, and existing development's on Venice Island, are all essentially limited to one access location.

Sound transportation planning dictates that a residential development comprised of more than 20 to 25 dwelling units should have at least two points of access. Desirably, both access points should be fully functional public accesses. In extreme circumstances, the second access point can be limited to emergency access only, or a single access point, if constructed wide enough to boulevard standards (i.e., two inbound lanes and two outbound lanes divided by a wide landscaped median), will serve as long as not constructed on a single deck bridge To my knowledge, none of these features are provided as part of the rezoning plans for the Venice Island properties. It is not difficult to imagine a traffic accident or other catastrophe closing the Flat Rock Bridge or the Cotton Street Bridge, or a simple railroad closure of Cotton Street, and emergency response personnel being unable to respond to a fire or medical emergency on Venice Island because there is no alternative access to a particular part of the island. (This may not have been a major concern of the past when the island population was limited. This has to be a critical concern with the addition of more than 500 families to the island.

In addition, some of the information you have provided for my use indicates that Venice Island is subject to occasional flooding, as depicted in one of your photographs taken in September 1999 after Hurricane Floyd. The Flood Map for Venice Island indicates that the entire island, including the sites for the three proposed residential developments, is within the 100 year floodplain. None of the information provided for my use indicates any measure taken, or procedures evaluated, for the emergency evacuation of Venice Island in the event potential flood conditions along the Schuylkill River.

The two existing bridges available for vehicular traffic are narrow two-way, two-lane bridges. A third bridge is available for pedestrian access in vicinity of Fountain Street, but this location is not convenient to the proposed residential developments. It is assumed that future residents of Venice Island will consider evacuation of the island in the event of impending flood conditions, and will consider removing all motor vehicles from the island. The same can be said for existing businesses on the island, including the removal of trucks and semi-trailers. Since it is not possible to predict the time of day or day of the week for flooding condition the worst-case scenario is probably during the weekday morning or afternoon commuter rush hours when Main Street is already congested.

An evacuation plan should evaluate the time frame for complete evacuation of the island or various times of a typical weekday or weekend day. This will include the time frame for notification of all residents and employees on the island, preparation by residents and employees to begin leaving the island and traffic controls necessary to aid in the evacuation of the island. The number of police and/or emergency personnel assigned to effect an evacuation must be quantified by task and location. Consideration for temporary closure of parts of Main Street and/or other nearby streets to accommodate vehicles evacuated from the island must also be quantified, and the effects on normal traffic operations in the area must be considered . Without an effective evacuation plan, there may be greater risk and hazard for residents of the island due to the unorganized evacuation of the island, than the threat posed by an actual flood.

In conclusion, based on the documentation made available to me, it is my opinion that the potential traffic impacts associated with a residential rezoning of three sites on Venice Island have not been considered. There is no information that indicates that any safeguards to the health, safety and welfare of residents, employees and visitors to the island and surrounding area, are considered. Before any decision is rendered on a rezoning request for the proposed Venice Island Residential Developments, the Zoning Board of Adjustment should have the benefit of having reviewed an up-to-date, site specific Traffic Impact Analysis. The Traffic Impact Analysis must demonstrate the traffic engineering strategies to be implemented to assure that safe and efficient access via multiple access points will be provided to each of the developments, Finally, if residential construction on an island within a floodplain is viewed as appropriate land use planning, an effective flood evacuation plan must be formulated so that the evacuation process does not represent a threat to the residents and employees on Venice Island.

If you should have any questions or wish to discuss this information in greater detail please all me at your convenience.


Andreas Heinrich, P.E., P.T.O.E.


cc: Stanley Krakower, Esq.