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NYC 9/11 Public Portal Document

when more precise information may be available, a use a knowledgeable traffic expert and/or consult with first-cut definition of potential impact locations can NYCDOT to ensure that the traffic study area is P be made. appropriately defined.

What are the problem locations or potential problem The completion of the trip generation and prelimi- locations along these routes or next to these routes nary traffic assignment steps first can provide a sound that could be affected by traffic generated by the basis for defining the traffic study area. It is also possible proposed action? It is useful to review information to "screen out" several analysis locations at this stage of available from previous reports and databases the work effort, providing that the preliminary trip regarding problem locations, and it is very important generation estimates and the preliminary traffic to drive or walk the area during peak travel hours to assignments are close to their final versions. Generally. make an informed determination. except for the intersections in the immediate vicinity of the proposed nroiect site intersections with fewer than 50 The traffic study area may be contiguous, or it may h of project traffic can be screened out It is also be a set of non-contiguous intersections combined into a possible that once the full traffic impact analyses have study "area." The traffic study area could extend from a been completed, the initially defined traffic study area minimum of one to two blocks from the site to as much as may need to be enlarged to encompass other intersections one-half mile or so or more from the site. The study area found likely t_ be impacted __ well. This is tvnically the need not have a particular shape; it could be rectangular, se when several intersections at the outer edges f the it could be a long and narrow area extending along a study area are significantly impacted. However, the study major route to the project site, etc. It is defined by the area should only be expanded in consultation with th e routes along which traffic proceeds to and from the site, gad agency and NYCDOT and typically includes major arterials and streets along the most direct routes to the project site as well as significant Another screen may be considered based on signif- alternate routes. Multilegged intersections and other icant impact guidelines that follow later in this traffic and problem locations along these routes should generally be parking section cha nter of the Manual. That is, if a pro- incorporated into the traffic study area. posed action would generate fewer than five peak hour vehicles through an intersection—any intersection—any Although it is difficult to outline the number of impacts there would not be considered significant, analysis locations encompassed within the study area for because the incremental volume of trips would be im- a detailed traffic analysis, in most cases it would range perceptible —If-such on intersection has been included from a low of 6 to 8 intersections or analysis locations to within the-traffic aJ analysed for J a high of about 30 gmpc such locations. The six-to- existing conditions to depict the sening of the proposed eight analysis location guideline reflects analyses at the action in full, but it does not need to be d for J four corners of a typical square block site plus one existing or future conditions with or without the project. additional analysis location along each approach route to Th final documentation of findingssi sh ou ld indicate 1.at the site. The 30 or more analysis location guideline thevolume of trips expected to pass through other reflects the potential to cover two or three avenues or routes to/from the site were found unlikely to be sufficient streets on each side of the site, as well. Obviously,a A to generate significant impacts. small-scale action that would generate a modest volume of peak hour trips in a congestion-free area could requ ire In addition to the above operation-based guidelines_ even fewer than the six-to-eight analysis location the traffic study area should also consider intersections or guideline but should not than th e f our main locations, which may be problematic from the safely viewpoint. High-accident locations_ if any, should be identified with NYCDOT and the traffic study a appropriate). However this should be based on th e hs ould include these intersections A fi h accident preliminary trip assignments Similarly, a major location is one where there were 5 or more nedestri development project in a congested section of the City accidents in any year in the most recent 3-year nerind that could require significantly more than 30 analysis data is available locations; "mega-projects" could encompass traffic study areas with 100 or more intersections. However, in the For programmatic actions, there are alternative event that the study area appears to be very large and approaches to defining the traffic study area, depending encompass significantly more than 30 analysis locations, on the nature of the programmatic action that is proposed care should be exercised that some of the intermediate and how much information exists about its implementa- locations within the area—but not on a direct route to the tion. A few case examples of how study area definitions site—are not included unnecessarily. It is advisable to have been made within CEQR until now illustrate this

CEQR MANUAL 3O-4 10/01

NYC-WTC 000137577