James H. Dunlop NCDOT Congestion Management Section Congestion Management Options to Improve Air Quality James H. Dunlop NCDOT Congestion Management Section

Ideal Driving Conditions

Usual Driving Conditions

A place where two or more roads meet Intersections A place where two or more roads meet

Conventional Intersection Conflict Points

Intersection Congestion What is the traffic control device that leads to more confusion, congestion and air pollution than any other?

Intersection Congestion The Traffic Signal

Signalized Intersections The Purpose of a Traffic Signal is to take the Right-of- Way assignment away from the main flow of traffic and assign it to lesser movements

Main Street Green Time Main Phase ~ 70% Green Main Phase ~ 50% Green

Signalized Intersections Eight-Phase Signal

Intersections Does every intersection need every movement served at the same location?

Alternative Intersection Design Concepts Separate conflicting movements Reduce conflicts Remove signals where possible Limit phases at signalized intersections Provide better signal coordination

Alternative Intersection Design Concepts Roundabouts Superstreets Quadrant Lefts Jughandles Offset “T” Intersections Continuous Flow Intersection

Circular Intersections 3 Types of Circular Intersections Traffic Circle Columbus Circle – New York City Market Square - Fayetteville 15

Circular Intersections 3 Types of Circular Intersections Traffic Circle Traffic Calming Intersection

Circular Intersections 3 Types of Circular Intersections Traffic Circle Traffic Calming Intersection Modern Roundabout Clemmons, Forsyth Co. NC State, Raleigh

Roundabout vs. Traffic Circle Size Traffic Circle - ~ 800’ Diameter Roundabout – ~ 180’ Diameter

Roundabout vs. Traffic Circle Deflection Traffic Circle – 90 degree entry Roundabout – 45-60 degree entry

Roundabout vs. Traffic Circle Entry Traffic Control Traffic Circle - Stop Roundabout - Yield

Why Roundabouts? Safest Intersection High Capacity / Low Delay Good for All Modes of Traffic Geometric Flexibility Aesthetics

Roundabouts - Safety There are 32 conflict points at a conventional intersection. There are only 8 conflict points at a modern roundabout

Crash Reductions Following Installation of Roundabouts Roundabouts - Safety Crash Reductions Following Installation of Roundabouts In the United States – 2007 Total Crashes 48% Fatal/Injury Crashes in Rural Areas 78% Fatal/Injury Crashes in Urban Areas 60% In North Carolina from 1999-2006 Conversion From Stop Sign Control 41% Conversion From Signal Control 74% Sources: Insurance Institute For Highway Safety www.highwaysafety.org NCHRP Report 572 onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_572.pdf NCDOT Safety Evaluation Group www.ncdot.org/doh/preconstruct/traffic/safety/Reports/completed.html

Roundabouts - Capacity and Operation Peak Hour Traffic – Usually at least as efficient (same overall delay to drivers) as traffic signals or all-way stops Off Peak Traffic – Usually much more efficient than traffic signals. Multi-lane roundabouts can handle as much traffic as a busy signalized intersection

Roundabouts – Multi-Modal Roundabouts provide a safer crossing for pedestrians

Roundabouts – Multi-Modal Roundabouts provide safer travel for cyclists PHOTOGRAPHY SOURCE: Lee Rodegerdts 26

Roundabouts – Multi-Modal

Roundabouts – Multi-Modal Buses do not have trouble negotiating the roundabout, and provide a good location for bus stops

Large Trucks PHOTOGRAPHY SOURCE: Lee Rodegerdts

Emergency Vehicles PHOTOGRAPHY SOURCE: Brian Walsh

Roundabouts – Geometric Flexibility

Roundabouts – Geometric Flexibility Roundabouts can be designed as ovals and oblong shapes in order to achieve better movement separation and accommodate unique intersection geometry Works well for offset T-type and multiple legged intersections Could be an option for median divided facilities where controlling access is an issue

Roundabouts – Geometric Flexibility Corridor Operation

Landscaping

Landscaping Bloomington, IN

Houten, the Netherlands Landscaping Houten, the Netherlands

Roundabout Air Emissions At a roundabout replacing a signalised junction, CO emissions - 29% NOx emissions - 21% fuel consumption - 28% At a roundabout replacing yield regulated junctions, CO emissions + 4% NOx emissions + 6% fuel consumption + 3% “The results indicate that the large reductions in emissions and fuel consumption at one rebuilt signalised junction can “compensate for” the increase produced by several yield-regulated junctions rebuilt as roundabouts.” The effects of small roundabouts on emissions and fuel consumption: a case study András Várhelyi, Department of Technology and Society, Lund University, Sweden 2001

Roundabout Air Emissions Better fuel efficiency and air quality Where roundabouts replace signals, idling decreases which reduces vehicle emissions and fuel consumption by 30 percent or more. http://www.dot.state.mn.us/roundabouts/ (Minnesota DOT)

NY State Study Roundabout vs. Signalized intersection

Intersection Costs Average Roundabout construction costs about $400,000 Maintenance is minimal (mostly mowing any additional landscaping is done by others) Signalized intersection costs are about $100,000 Signal maintenance costs are about $3,000-5,000 annually Construction of turn lanes is about $75,000-$150,000

North Carolina Roundabouts Inventory as of August 2010

Single Lane Roundabouts Clemmons, Forsyth Co.

Single Lane Roundabouts NC State, Raleigh

Multi Lane Roundabouts Davidson, NC Griffith Street and Davidson Gateway Drive Griffith Street and Jetton Street

Superstreets A type of intersection in which minor cross-street traffic is prohibited from going straight through or left at a divided highway intersection. Minor cross street traffic must turn right, but can then access a U-turn to proceed in the desired direction. *Other configurations possible based on site specific conditions.

Economically Beneficial Environmentally Responsible Why Superstreets? Improved Safety Less Travel Time Economically Beneficial Environmentally Responsible

Why Superstreets? Improved Safety Reduced conflict points (especially crossing movements) leads to reduced crashes

Superstreet Conflict Points Total Conflict Points = 14 Improved Safety

Superstreet Benefits and Capacities (Research Project 2009-06) Safety impact by collision type for unsignalized superstreets, % Collision Type Crash Reduction % Total -46 Fatal and injury -63 Angle and right turns -75 Rear ends -1 Sideswipes -13 Left turns -59 Other -15 50

Why Superstreets? Less Travel Time Reduced “wait time” or delay Increased roadway capacity Improved signal coordination

Superstreet Phasing

Superstreets

Superstreet- US 321 Hickory-Lenoir 2035 Full Network Delay Analysis (Traditional Build vs. Three-lane Superstreet Build)   AM PM Traditional Superstreet % Change Vehicles Exited (veh / hr) 31,760 35,618 12.15% 31,358 34,601 10.34% Vehicles Entered (veh / hr) 33,730 37,283 10.53% 34,039 36,494 7.21% Travel Distance (mi) 76,355 86,120 12.79% 73,721 82,465 11.86% Travel Time (hr) 10,121 6,628 -34.52% 10,245 7,051 -31.17% Total Delay (hr) 8,488 4,755 -43.98% 8,671 5,250 -39.45% Total Stops (number) 111,713 122,511 9.67% 120,421 119,534 -0.74% Fuel Usage (gal) 44,308 39,617 -10.59% 44,001 39,781 -9.59% Per Veh. Distance (mi) 2.4 2.42 0.57% 2.35 2.38 1.38% Per Veh. Time (hr) 0.32 0.19 -41.61% 0.33 0.2 -37.62% Per Veh. Delay (hr) 0.27 0.13 -50.05% 0.28 0.15 -45.13% Per Veh. Stops (number) 3.52 3.44 -2.21% 3.84 3.45 -10.04% Per Veh. Fuel (gal) 1.4 1.11 -20.27% 1.15 -18.06%

2009 – Looking south above Evans Road, PM peak US 281 (San Antonio TX) 2009 – Looking south above Evans Road, PM peak

US 281 Superstreet Comments As traffic congestion on U.S. Highway 281 eases due to the completion of the superstreet project, construction of new commercial and retail developments along the far North Central San Antonio corridor is ramping up. “We are close to 90 percent leased with no pad sites left,” Elliott remarked. “We've had quite a bit of interest because of the market, which is in a high growth area. And a lot of our tenants say they feel like business has increased since the superstreet was finished.” San Antonio Express-News March 17, 2011

Economically Beneficial Why Superstreets? Economically Beneficial Preserves the existing facility Less expensive than an interchange Provides good access to both sides of the main road for development

UPS Expects To Save $600 Million by Favoring Right Hand Turns

Environmentally Responsible Why Superstreets? Environmentally Responsible Less time spent idling at a red light Reduction in environmental pollutants (exhaust fumes / fuel usage) Less acreage impacted by construction and permanent facility

Superstreet-US 15-501 Chapel Hill

Superstreets US 15-501 Chapel Hill

Offset “T” Intersections Two 3-Phase Signals Operate Better than an 8-Phase

Alternative Intersection Concepts Don’t Allow the “Simple” Fourth Leg

What is a Quadrant Roadway? A network of adjacent intersections that work together to relieve congestion at a busy intersection Goal is to relieve one congested traffic signal with three or more simpler, less congested traffic signals “Simpler” = fewer “phases” at signal

NC 73 Quadrant Roadway

Capacity Analysis Results 2030 Design Year Peak Periods 2030 Primary Network Delay Analysis (Full Movement vs. Quadrant Left)   AM PM Full Movement Quadrant Left % Change Vehicles Exited (veh / hr) 6,127 7,736 26.26% 7,425 9,087 22.38% Vehicles Entered (veh / hr) 6,234 7,774 24.70% 7,557 9,231 22.15% Travel Distance (mi) 2,985 3,595 20.45% 3,512 4,256 21.19% Travel Time (hr) 1,128 273 -75.81% 1,566 654 -58.22% Total Delay (hr) 1,044 169 -83.86% 1,464 527 -63.99% Total Stops 11,310 9,785 -13.48% 15,851 14,378 -9.29% Fuel Useage (gal) 358 186 -48.01% 473 291 -38.59% Per Veh. Distance (mi) 0.49 0.61 25.00% 0.29 0.35 19.52% Per Veh. Time (hr) 0.20 0.04 -82.79% 0.21 0.07 -65.86% Per Veh. Delay (hr) 0.17 0.02 -87.21% 0.06 -70.58% Per Veh. Stops 1.85 1.26 -31.48% 2.13 1.58 -25.88% Per Veh. Fuel (gal) -58.83% 0.03 -49.82%

Jughandles Main Street – No Lefts

Ingress and Egress Movements at Same Time Left In/Out Access Ingress and Egress Movements at Same Time

Left Turns Move During Same Phase as Throughs Continuous Flow (CFI) Left Turns Move During Same Phase as Throughs

Side Street Left Turn at Same Time as Main Left Continuous Flow (CFI) Side Street Left Turn at Same Time as Main Left

Continuous Flow (CFI)