00741908

Component

https://doi.org/10.3141/1579-03

http://scholar.google.com...Nolf&publication_year=1997

Multilane trunk-line (state routes other than freeways) highways in the state of Michigan typically have one of two cross sections: five-lane or boulevard. The cross section of a five-lane facility consists of four through lanes and a continuous two-way center left-turn lane. The alternative to the center left-turn lane design is a divided highway with a median. The median widths may vary from as little as 1.2 m (4 ft) to more than 30 m (100 ft). Since left turns at intersections have a major effect on limiting the capacity of the intersection, Michigan uses directional U-turn crossovers to provide for an "indirect left-turn" maneuver at signalized intersections. The alternative to this boulevard strategy is to provide for direct left turns with a left-turn phase at the intersection. It was impossible to find appropriate locations in the field to evaluate the sensitivities of these designs and operations with various traffic volumes and left-turn volumes. Thus, computer modeling, via TRAF-NETSIM, was used to evaluate these designs operationally. The boulevard designs that used indirect left-turning strategies and signalized crossovers were superior, in most cases, to all other designs considered. The boulevard designs that used direct left-turning strategies had proportionally higher amounts of delay than all other designs considered, and their operation tended to fail as the percentage of left turns and traffic volume increased. In addition, with low percentages of left turns, the operation of a boulevard with an indirect left-turn strategy was similar for both signalized and stop-controlled crossovers.

This paper appears in Transportation Research Record No. 1579, Geometric Design and Its Effects on Operations.

English

p. 18-26

1997

Transportation Research Record

030906158X

Figures (9) ; Photos (2) ; References (2) ; Tables (1)

Arterial highways; Crossovers; Divided highways; Left turns; Operations; Signalized intersections; Simulation; State highways; Traffic delays; Traffic volume

Five lane highways; Operational analysis

Michigan

Administration and Management; Design; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure

TRIS, TRB

Oct 6 1997 12:00AM

• EFFECTS OF INADEQUATE DRIVEWAY CORNER CLEARANCES ON TRAFFIC OPERATIONS, SAFETY, AND CAPACITY
• FIELD ANALYSIS OF OPERATION AND DESIGN OF SINGLE-POINT URBAN INTERCHANGES
• FORMULATION AND VALIDATION OF OPERATING SPEED-BASED DESIGN CONSISTENCY MODELS BY BOOTSTRAPPING
• GUIDELINES FOR OFFSETTING OPPOSING LEFT-TURN LANES ON DIVIDED ROADWAYS
• GUIDELINES FOR RIGHT-TURN TREATMENTS AT UNSIGNALIZED INTERSECTIONS AND DRIVEWAYS ON RURAL HIGHWAYS
• MODEL FOR MINIMUM DRIVEWAY CORNER CLEARANCES AT SIGNALIZED INTERSECTIONS
• MODELING HEADLIGHT SIGHT DISTANCE ON THREE-DIMENSIONAL HIGHWAY ALIGNMENTS
• OPERATING SPEED ON SUBURBAN ARTERIAL CURVES
• OPERATIONAL IMPACT OF SPLIT INTERSECTIONS
• RURAL TWO-LANE PASSING HEADWAYS AND PLATOONING
• STATE-OF-THE-ART DESIGN OF ROUNDABOUTS