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Office of Planning, Environment, & Realty (HEP)

Flexibility in Highway Design

Case Studies - Route 9 Reconstruction: New York, NY

Aerial view of West Side Highway (looking South), circa 1970.

Borough of Manhattan, New York, NY

Aerial view of West Side Highway


After more than 20 years of planning and design efforts, the reconstruction of what was formerly known as the West Side Highway has now begun. The project proposes to reconstruct State Route 9A from Battery Place to 59th Street along the western edge of Manhattan. This 5mile section of roadway lies at the southern end of New York State Route 9A, which begins at the BrooklynBattery Tunnel and extends northward for approximately 76 km (47.5 miles), until it merges with U.S. Route 9 in Peekskille, NY in northern Westchester County. Commonly known as West Street, Eleventh Avenue, Twelfth Avenue, the West Side Highway, or the Miller Highway, this portion of State Route 9A plays a vital role in the regional transportation system of the New York metropolitan area.

map: Manhattan from W. 79th Street to Battery Park. Route 9A detailed on the left drawing: outline map of the US with New York in black. Text: Borough of Manhattan, NY, NY with arrow pointing to location

Location site map

Previously, this portion of Route 9A comprised the West Side Highway, an elevated limitedaccess roadway originally constructed in the 1930's between the Battery and 72nd Street, and a service road and local service street beneath the elevated roadway terminating at 59th Street. After the collapse of a portion of the elevated roadway in the early 1970's, and in recognition of its overall deteriorated condition, the entire section of highway from the Battery to 59th Street was closed to traffic in 1974. The elevated structure was subsequently demolished in the late 1970's, and the existing atgrade roadway was repaved to serve as an interim roadway until a permanent replacement for the West Side Highway could be constructed.

A proposal originally conceived in the early 1970's for the construction of a sixto eightlane interstate freeway facility known as Westway, which would have been partly elevated and partly depressed below grade, was withdrawn in 1985. The Westway funds were redistributed to several transportation projects in the city of New York, one of which was for the reconstruction of the interim roadway and its improvement into a permanent facility. The primary purpose of the Route 9A reconstruction project is to address the numerous problems and deficiencies associated with the continued use of the interim roadway and to accommodate some of the traffic that was diverted to other streets in the area when the elevated roadway closed.

Section of collapsed West Side Highway in 1972.
photo: aerial view of collapsed West Side Highway

The Route 9A facility serves a variety of regional, arterial, and local transportation activities and needs. It is an important interconnection between the BrooklynBattery Tunnel, the Franklin D. Roosevelt (FDR) Drive and the East River Bridges via the Battery Park underpass, the Holland Tunnel, the Lincoln Tunnel, and the West Side Highway/Henry Hudson Parkway, which provides access to the George Washington Bridge, the CrossBronx Expressway, and points north.

The roadway is a major northsouth artery in Manhattan's street grid that serves through movements to and from the borough. It is also a local street that provides vehicular and pedestrian access to the activities, businesses, and residences that line its rightofway. The roadway also serves important intermodal functions by providing access to three Hudson River ferries, passenger liner terminals, excursion ships, and a heliport, and by serving as the terminus point for five crosstown bus lines.

The existing traffic volumes on the roadway reflect Route 9As importance in the region's transportation system. Route 9A serves regional, arterial, local, and intermodal transportation functions. Average daily twoway traffic volumes range from 69,000 to 81,000 vehicles. With the closure and demolition of the elevated West Side Highway, the New York City DOT estimates that as many as 10,000 vehicles per day have diverted to Manhattan's other northsouth routes, further taxing the capacity of these already congested roadways.
At a number of the key intersections along existing Route 9A during peak travel hours, traffic volumes approach or exceed theoretical roadway capacity. At these times, vehicular travel speeds on several segments of the existing roadway have been observed to drop to less than 3 mph (normal walking speed). Clearly, the existing "interim" facility is in need of substantial improvement.


In 1987, the city of New York and New York State established a joint West Side Task Force in an attempt to reach a consensus on what action should be taken to replace the deficient interim highway. The task force ultimately developed the concept of creating an atgrade sixlane urban boulevard as the most appropriate solution to the identified problems. The primary goals, objectives, and design principles developed by the Task Force formed the basis for the subsequent Environmental Impact Statement (EIS) and project planning and design phases of the Route 9A project.

The project encompassed the full gamut of issues and concerns associated with providing major improvements to an existing transportation facility in an established urban area. In addition to issues that are typically encountered in major improvement projects, such as potential impact on adjacent land uses (including parks and historic structures) and air quality and noise effects, a number of other considerations were addressed during the project planning and design process. These included the following:

  • The degree to which traffic using the facility would intrude into adjacent residential and commercial neighborhoods.
  • The appropriate size of the median area.
  • The accommodation of pedestrian movements across the highway from the existing developments on the east side to the planned linear park along the Hudson River waterfront.
  • Separation of bicycle and pedestrain traffic.
  • Access to commercial activities.
  • The design of street light standards.


Recommended Design Concept

The alternative ultimately selected through the EIS process is a basic sixlane urban boulevard with three travel lanes provided on either side of a raised, landscaped median. In a few locations, four travel lanes are provided along one side of the median area to better accommodate projected peakperiod travel demands.

Existing cross section

Technical drawing of the existing cross section. Elements include: lanes, median, parking, sidewalk, and variables
Proposed cross section
Technical drawing of proposed cross section. Elements include: walkway, bikeway, buffewr, lanes, median, parking, and sidewalk.

A distinguishing feature of the final design is the use of barrier curbs that are .50 m to .85 m (20 in to 34 in) high along both sides of the center landscaped median and along the roadway edge with the riverside linear park. This higher harrier curb provides for substantially more soil around each tree and thus allows many more trees in total than would have been possible with a standard .15m to .20m (6in to 8in) urban curb. The latter curb height will be provided along the more developed east side of the new boulevard.

Existing roadway in vicinity of 34th Street (looking south)

photo: existing part of Route 9 near 34th Street
Functional Classification Principal urban arterial street
Design Traffic Volumes 20-year projection from completion of project construction
Design Speed 40 mph
Level of Service Sight D (desirable)
Distance Crest -275-ft
Sag -Riding comfort controls
Grades 7% maximum
5% desirable
Alignment 573-ft minimum radius
Cross Slope 2% (planar)
Superelevation 4% maximum
Vertical Clearance 14.5-ft minimum
Lane Width 11-ft through lane
11-ft left-turn lane
1-ft offsets to curb or barrier
Number of Lanes 6 to 8 with turning and acceleration lanes as necessary
Medians 19-ft for mainline at-grade sections
(face of curb to face of curb)
4.5-ft minimum for depressed, elevated, and constricted sections
Curbs East side -7-in curb
Median -7-in curb and/or 20-in to 34-in barrier
West side -7-in curb and/or 20-in to 34-in barrier
Pedestrian ramps at all crosswalks
Shoulders None, except 2-ft left and 6-ft right on structure at Canal Street and in depressed section at 34th and 42nd Streets
Parking lane east side
Drainage 1O-year storm -surface and closed system
50-year storm -depressed roadway
Border and Sidewalks 15-ft -east side sidewalk, 8-ft where constricted
15-ft -west side walkway, 8-ft where constricted
9-ft -buffer area west side of roadway
Parking Lanes 10-ft east side, commercial areas; 8-ft residential areas
Bikeway 12-ft mainline; 8-ft min. where constricted
Street Lighting Roadway- 1.0 fc (see note)
Depressed -5.0 fc
Tunnels -50/5 fc, day; 5.0 fc, night
Horizontal Clearance 2-ft from face of curb to fixed objects

Note: fc = footcandle

General design criteria employed on the Route 9A reconstruction project.

The facility will have 3.3m (11ft) travel lanes with .30m (1ft) offsets from the .50m to .85m (20in to 34in) barrier curb. The high barrier curb has been crash tested by FHWA Region 15 staff to a speed of 70 kph (45 mph) and is similar to that used on the Washington, DC area parkway system. The curb was selected as an alternative to the use of shoulders, which are preferred in the AASHTO Green Book for a facility of this functional classification and design speed.

The new facility uses a design speed of 65 kph (40 mph) and will have a posted speed limit of 55 kph (35 mph), even though the project's functional classification as a principal urban arterial street would have allowed for a much higher design speed to be used.

Detailed Traffic Analysis

The traffic analysis performed as part of the EIS process was very detailed, and ultimately covered almost all of Manhattan. This analysis determined that virtually none of the users of the highway were traveling over its complete length, but rather using it to gain access to the eastwest street system on the island. The road thus operates, both today and in the future, as essentially a collectordistributor system between the BrooklynBattery Tunnel on the south and the elevated Henry Hudson Parkway on the north.

To prevent the intrusion of through traffic into adjacent residential areas, a number of the originally proposed median openings will be closed, allowing only rightturn in and rightturn out movements between the northbound boulevard travel lanes and the eastwest street system.

Pedestrian Movements

Pedestrian movements back and forth across the highway were examined extensively. Indeed, one of the major design elements of the project is the integration of the highway improvements with the pedestrian crossings to the planned Hudson River Waterfront Park. In addition, a small existing city park at 23rd Street will be greatly expanded (ultimately to encompass more than a full city block) both as a new urban amenity and to provide improved traffic operations in this area.

An associated feature is the use of a "bulbout" design along the east side of the highway at all intersections to better delineate the curb parking areas and to help minimize the pedestrian crossing distances across the travel lanes. These designs will be closely coordinated with the pedestrian crossing points on the landscaped median.

Computergenerated illustration of separated pedestrian promenade and bicycle pathway along the river side of reconstructed Route 9A.
Computergenerated illustration of separated pedestrian promenade and bicycle pathway along the river side of reconstructed Route 9A

Separation of Pedestrian and Bicycle Traffic

In this part of Manhattan, as in many urban areas, there are significant conflicts between pedestrians and bicyclists. A design element incorporated to alleviate this conflict along the river side of the boulevard is the provision of a separate 4.9mwide (16ft) bikeway for use by bicyclists and rollerbladers (both recreational and commuter) and a parallel 4.6mwide (15ft) pedestrian pathway-promenade.

The Street Light Design Issue

As the design concept moved into the formal preliminary and final design phases, a major issue that was successfully resolved concerned the design of the street lights along the project. The design of the standard New York State Department of Transportation (NYSDOT)/city of New York steel street light pole was deemed by community representatives to be out of keeping with the overall urban boulevard concept.

After some additional research, it was discovered that the light poles that were being used in the privately developed Battery Park West (a mixeduse office/retail/residential development) were replicas of a design originally found throughout the city of New York in the early part of this century. This replica design is being incorporated along the length of the project.

Unique street light design enhances aesthetics.

drawing: man next to ornate street light with a car in the roadway

Other Notable Design Elements

No formal design exceptions were requested for this project by the New York State DOT. All the design elements are within AASHTO allowable ranges. Some of the special elements that have been incorporated into the final design of the project include the following:

  • Compatibility with the Hudson River Park Conservancy in terms of paving materials, dimensions of paving and planting strips, plant materials, and other elements.
  • Reuse of existing granite paving blocks found along the waterfront area as edge treatments between the separate bicycle and pedestrian paths.
  • Use of mixed plant materials (grass, shrubs, and trees) in the median area, as opposed to use of all trees or all grass, to better reflect the character of the adjacent land uses along each segment of the highway.


This project has the potential for widespread application across the Nation as an illustration of the manner in which a collaborative, multidisciplinary planning and design process, incorporating a high level of continuous public involvement, can result in the creation of a worldclass street design.

It also illustrates how detailed investigations of travel demand and traffic movement patterns can result in a dramatic change in the scale of the proposed improvement, from a six to eightlane elevated urban freeway to a sixlane urban boulevard with a design speed of 65 kph (40 mph).

Setting: Midtown Manhattan, New York, NY
Length: 8.2 km (5.1 miles)
Traffic Volume: At 59th Street -northern project limits
3,600 vehicles per hour
(1988 AM peak hour, peak direction)
3, 750 vehicles per hour
(1998 AM peak hour, peak direction)
3,900 vehicles per hour
(2018 AM peak hour, peak direction)
Design Speed: 65 kph (40 mph)
Type of Road: 6- to 8-lane, median-divided urban principal arterial street
Design Cost: $18 million (1994 estimate)
Construction Cost: $380 million ( 1994 estimate), including engineering design,
construction supervision, right-of-way, and inflation
Key Design Features: Use of lowered design speed to mitigate right-of-way impact and to reflect urban character of surrounding development; use of high barrier curbs along both sides of center-Iandscaped median and along roadway edge with riverside linear park; treatment of pedestrian crossing areas; provision of separate pathways for bicyclists and pedestrians
Debits: None reported
Similar Projects: West Main Street, Westminster, MD
Carson Street, Torrance, CA
Contacts for
Additional Information:
Mr. Douglas A. Curry, P:E.
Director, Route 9A Reconstruction Project

Ms. Heather T. Sporn
Landscape Architect
Route 9A Reconstruction Project
New York State DDT
141 Fifth Avenue (at 21" St.), 7th FI.
New York, NY 10010
Tel: 212-979-6630
Fax: 212-979-6638
Updated: 3/12/2012
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