CIV 412 CLASS PROJECT Presentation File

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

SAGTIKOS PARKWAY EXIT 41A WESTBOUND SOUTHERN STATE NORTHBOUND SAGTIKOS PWKY

PARKWAY HISTORY The Sagtikos Parkway is a major north–south route in Suffolk County, originally constructed in the 1950s as part of Robert Moses’ vision for improved parkway connectivity across the region.

It was designed to link the Northern State Parkway and the Southern State Parkway, effectively serving as a central spine connecting eastern and western Long Island.

The parkway was named after the nearby Sagtikos Manor, a historic estate dating back to the 17th century.

Over the decades, the Sagtikos has evolved into a heavily trafficked commuter route due to Long Island’s population growth and suburban expansion.

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

Despite its scenic, limited-access design, it now faces congestion and aging infrastructure issues. Various improvement projects have been proposed, including capacity expansions and interchange upgrades, to address increasing traffic demands.

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3D GOOGLE SHOWING THE EXIT 41A ON-RAMP TO SAGITKOS NORTHBOUND. MAGENTA CIRCLE SHOWS DRONE LOCATION.

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

CONCRETE REPAIRS TO EXISTING ROADWAY TO BE COMPLETED OFF HOURS, SUNDAY THROUGH THURSDAY, FOR THE DURATION OF ONE MONTH OR AS WEATHER PERMITS.

N ROADWAY SPECS NUMBER OF LANES LANE AND SHOULDER WIDTH ROADWAY MATERIAL CURB TYPE OFF SHOULDER ACCESS INTERCHANGE DENSITY PERCENTAGE TRUCK/RV LOCATION CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

2 LANES 11’-0” // 6” ASPHALT/CONCRETE ROLL/MOUNT. CURB LARGE/GRASS SUBURBAN/URBAN

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DRONE IMAGES SHOWING THE EXIT 41A ON-RAMP TO SAGITKOS NORTHBOUND. CONSTRUCTION VEHICLES STAGED ALONG THE LEFT SIDE OF EXIT RAMP, WITH CONES AND LIGHTING TO THE RIGHT OF THE SHOULDER. CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

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TRAFFIC AADT

101,040 VEHICLES

PRIMARY USE OF ROAD

COMMUTER/NON-COM. TRUCKS NOT PERMITTED CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

LOCATION MOSTLY SURBURBAN ENVIRONMENT SURROUNDING THE PASSENGER-VEHILCE-ONLY PARKWAY. ROADWAY RUNS BETWEEN TWO DISTINCT NEIGHBORHOODS AND SERVES AS AN IMPORTANT POINT OF CONNECTION BETWEEN THE LONG ISLAND EXPRESSWAY (NORTH) AND SOUTHERN STATE PARKWAY (SOUTH).

N CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

Above shows I495 Eastbound Exit toward Sagtikos Parkway North.

Below shows plan view of Sagtikos Parkway.

According to recent data from NYSDOT’s GIS traffic map, the Annual Average Daily Traffic (AADT) at a specific segment of the Sagtikos State Parkway—just north of the Southern State Parkway interchange—is approximately 101,040 vehicles per day. This high volume highlights the importance of the Sagtikos Parkway as a key north-south transportation corridor in western Suffolk County. The data reflects significant usage in this area, likely due to its connections with major east-west highways such as the Southern State Parkway and the Long Island Expressway.

The AADT figure emphasizes the parkway’s role in supporting heavy daily commuter and regional traffic across Long Island.

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

Sagtikos Parkway Calculations Number of lanes: 2 lanes Lanes width: 11 ft Shoulder width: 6 inches

CALCULATION

Location: Suburban / Urban 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑐ℎ𝑎𝑛𝑔𝑒𝑠

4

Interchange density = 𝑆𝑒𝑔𝑚𝑒𝑛𝑡 𝑙𝑒𝑛𝑔𝑡ℎ (𝑖𝑛 𝑚𝑖𝑙𝑒𝑠) = 5.14 = 0. 78 Truck Percentage = 0 %

Annual average daily traffic (2023) = 51,343 Directional design hour volume = 4,284 Truck % = 0 Lanes = 2 Speed = 55 mph Free flow speed: 𝐹𝐹𝑆 = 𝐵𝐹𝐹𝑆 - 𝑓𝐿𝑊 − 𝑓𝐿𝐶 − 𝑓𝑁 − 𝑓𝐼𝐷

𝐹𝐹𝑆 = 70 − 1. 9 − 3. 0 − 4. 5 − 1. 3 = 59. 3 𝑚𝑝ℎ

The calculations presented for the Sagtikos Parkway provide a clear application of the Highway Capacity Manual (HCM) methodology for basic freeway segments in a suburban/urban context.

Using a base free-flow speed (BFFS) of 70 mph, appropriate adjustments were applied for lane width (−1.9 mph), lateral clearance (−3.0 mph), number of lanes (−4.5 mph), and interchange density (−1.3 mph), resulting in an adjusted free-flow speed (FFS) of 59.3 mph. The computed passenger car flow rate per lane—2,450 pc/hr/ln—accounts for the peak hour factor (PHF = 0.92), number of lanes (2), and the heavy vehicle adjustment factor (which is 1.0 due to 0% truck percentage).

Dividing flow rate by FFS yields a density of 41.3 pc/mi/ln. According to HCM thresholds, this corresponds to Level of Service (LOS) E, which is consistent with high traffic volumes and limited maneuverability. The methodology is correct, and all relevant factors appear to be reasonably considered.

Passenger car flow rate: 𝑉

4,284

𝑉𝑝 = 𝑃𝐻𝐹×𝑁×𝑓 ×𝑓 = 0.92×2×0.95 = 2, 450 𝑝𝑐/ℎ𝑟/𝑙𝑛 𝐻𝑉

𝑃

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

CONCLUSION This project analyzed a 5.14-mile segment of the Sagtikos Parkway, a major north-south corridor in Suffolk County, Long Island, New York. The parkway serves as a critical connector between key highways, including the Long Island Expressway (I-495), the Southern State Parkway, and the Northern State Parkway, making it an essential route for both commuters and regional traffic.

Within this segment, four interchanges were identified, resulting in an interchange density of 0.78 per mile—consistent with the design of a limited-access parkway that balances accessibility with uninterrupted flow. The Average Annual Daily Traffic (AADT) of 51,343 vehicles underscores the parkway's significance in the regional transportation network.

Traffic analysis revealed a free-flow speed of 59.3 mph, suggesting efficient travel under ideal conditions.

The estimated passenger car flow rate of 2,450 vehicles per hour per lane reflects the high demand placed on this corridor.

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

KEY TAKEAWAY Project Scope: Analyzed a 5.14-mile segment of the Sagtikos Parkway in Suffolk County, Long Island, NY. Connectivity: Connects major highways—LIE (I-495), Southern State Parkway, and Northern State Parkway.

Interchange Density: 4 interchanges, resulting in 0.78 interchanges per mile.

Traffic Volume: AADT of 51,343 vehicles, indicating significant usage.

Speed and Flow: Free-flow speed measured at 59.3 mph under ideal conditions.

Lane Capacity: Passenger car flow rate of 2,450 vehicles per hour per lane.

Conclusion: The parkway is a vital infrastructure component, currently performing well, but requires continued monitoring and planning to maintain efficiency.

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

REFERENCES Wikipedia contributors. (n.d.). Sagtikos State Parkway. Wikipedia. Retrieved May 4, 2025, from https://en.wikipedia.org/wiki/Sagtikos_State_Parkway New York City Roads. (n.d.). Sagtikos State Parkway. Retrieved May 4, 2025, from http://www.nycroads.com/roads/sagtikos/ New York State Roads. (n.d.). Southern State & Sagtikos Parkway. Retrieved May 4, 2025, from https://nysroads.com/list-smsp.php New York State Department of Transportation. (2024, July 8). Traveler advisory: Sagtikos Parkway construction update. Retrieved May 4, 2025, from https://www.dot.ny.gov/news/traveler-advisories/2024/2024-07-082

CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA

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CIV 412 HIGHWAY DESIGN RESTREPO / MARTILOTTA / WASIUTA / GARCIA