Human Factors Guidelines for Road Systems: Second Edition (2012) / Chapter Skim
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Pages 94-106
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From page 94... ...
Task Analysis of Driver Merging Behavior at Freeway Entrance Ramps .
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From page 95... ...
T AS K A NA LY SI S OF D RI VE R M ER GI NG B EH AV IO R AT F RE EW AY E NT RA NC E R AM PS In tr od uc ti on Merging fro m an entrance ramp onto the freeway ma inline can be a challenging task for drivers. For exa mp le, 36% of all ra mp accidents on urban interstates in Northern Virginia occurred when drivers were entering the freeway ( 1 )
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From page 96... ...
Di scu ssi on Initial steering component : The initial steering co mp onent occurs when drivers transition from the entrance ra mp onto the SCL. This steering ti me is approximately 1 s in length, derived from empirical research on steering ( 4 )
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From page 97... ...
R ED UC IN G W RO NG -W AY E NT RI ES ON TO F RE EW AY E XI T R AM PS In tr od uc ti on Reducing wrong-way entries onto freeway exit ramps refers to treatments that can be used to reduce the frequency of dr iv ers entering freeways by using the exit ramps. An average of 350 fatalities occur each year in the United States as a result of wrong-way crashes on freeways ( 1 )
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From page 98... ...
Di scu ssi on All of the characteristics listed in the guideline on the previ ous page correspond to mi ssing cues that can help drivers deter mi ne that they have start ed down the roadway, particularly an exit ramp, in the wrong direction. Light land use and low traffic volumes : Wrong-way driving crashes tend to occur in areas with light land use and low levels of traffic.
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From page 99... ...
DRIVER EXPECTATIONS AT FREEWAY LANE DROPS AND LANE REDUCTIONS Introduction Matching driver expectations at freeway lane drops is important because lane drops represent a situation that may violate driver expectations and cause confusion when th e driver expects the lane to continue on the freeway mainline. This confusion can result in high speed variability, erratic maneuvers, and driver frustration ( 1 )
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From page 100... ...
Discussion It should be noted that the lane drop guidance provided by Goodwin (2) is not specific to exit lane drops as they are commonly referred to today.
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From page 101... ...
DRIVER INFORMATION NEEDS AT COMPLEX INTERCHANGES Introduction Accommodating driver expectations at interchanges is paramount to navigational success. Expectations refer to "a driver's readiness to respond to situations, events, and information i n predictable and successful ways" ( 1 )
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From page 102... ...
Di scu ssi on Overall, there is little information available in the research literature that provides specific guidance related to supporting driver expectations at interchanges. The information provided in the guideline on the previous page is generally related to principles of geometry, signage, and sight distance to s upport elements of driver expectations at interchanges.
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From page 103... ...
A RRO W - PE R -L AN E S IG N D ES IG N TO S U PPO RT D RI VE R N AV IG AT IO N In tr od uc ti on Arrow-per-lane (APL) signs are com posed of prim arily two parts: arrows that point to individual lanes, and the destination inform ation listed above the arrows.
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From page 104... ...
Di scu ssi on The drivers' reading goal is to associate destination information with an arrow which points to a particular lane. To accom plish this goal, the pertinent destination inform ation mu st be able to be separated from adjacent information and clearly pertain to one or mo re arrows.
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From page 105... ...
DRIVER BEHAVIORAL TRENDS BASED ON EXIT RAMP GEOMETRY Introduction Exit ramps provide the means of accessing adjacent surface streets from a freeway. Well-designed exit ramps provide sufficient area for vehicles to depart from the main freeway lanes and sufficient distance for vehicles to decelerate comfortably from freeway speeds to a speed appropriate for the controlling feature of the ramp, which may be the first curve encountered along the ramp or it could be the crossroad terminal.
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From page 106... ...
De si gn Gu id an ce On an exit ramp, deceleration is accomplished first as the driver removes his/her foot from the throttle and the vehicle coasts in gear for a period of time (ty p ically ) without the use of brakes, and then the driver applies the brake s and de celerates comfortably .
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