Vehicle Speed Characteristics and Alignment Design Consistency for Mountainous Roads

Nama, Suresh; Maurya, Akhilesh Kumar; Maji, Avijit; Edara, Praveen; Sahu, Prasanta K.

doi:10.1007/s40890-016-0028-3

Cited by 37 publications

(19 citation statements)

References 13 publications

(23 reference statements)

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“…However, vehicle fitted with GPS devices can make driver over sensitive about vehicle speed (Nama et al 2016). Data collection using roadside laser detectors and sensors cannot identify vehicle categories accurately.…”

Section: Study Objectivesmentioning

confidence: 99%

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Operating Speed Prediction Model as a Tool for Consistency Based Geometric Design of Four-Lane Divided Highways

et al. 2019

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Researchers have studied two-lane rural highways to predict the operating speed on horizontal curves and correlated it with safety. However, the driving characteristics of four-lane-divided highways are different. Weak lane discipline is observed in these facilities, which influences vehicle speed in adjacent lane or space. So, irrespective of its lane or lateral position, vehicles in four-lane divided highways are considered free flowing only when it maintains the minimum threshold headway from any lead vehicle. Examination of two conditions is proposed to ensure the free flow. Vehicles meeting both conditions, when tracked from the preceding tangent section till the centre of the horizontal curve, are considered as free flowing. The speed data of such free flowing passenger cars at the centre of eighteen horizontal curves on four-lane divided highways is analysed to develop a linear operating speed prediction model. The developed model depends on curve radius and preceding tangent length. The operating speed of passenger car in four-lane divided highways is influenced by horizontal curve of radius 360 m or less. Further, longer tangent would yield higher operating speed at the centre of the curve. Finally, two nomograms are suggested for conventional design, consistency based design and geometric design consistency evaluation of four-lane divided horizontal curves.

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Section: Study Objectivesmentioning

confidence: 99%

“…Table 1 represents the summary of a few relevant models. Gong and Stamatiadis (2008) (Nama et al 2016). However, availability of speed prediction model for four-lane divided horizontal curves is very limited, especially in developing countries.…”

Section: Introductionmentioning

confidence: 99%

Operating Speed Prediction Model as a Tool for Consistency Based Geometric Design of Four-Lane Divided Highways

et al. 2019

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“…The influence of horizontal and vertical alignment on their traffic operation was studied on 19 uniform segments from Spain; it was proved that deviations on horizontal alignment or longitudinal profile may produce bad estimation if they are not considered on the analysis procedure [7]. The 85th percentile vehicle speed had been adopted as part of geometric design consistency evaluation criteria [8].…”

Section: Introductionmentioning

confidence: 99%

An Optimization Design Method of Combination of Steep Slope and Sharp Curve Sections for Mountain Highways

Yue

Wang

2019

Mathematical Problems in Engineering

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As it was found steep slope and sharp curve sections account for 14% of the accident-prone sections according to the accidents data in Chongqing. Regular design indices with certain thresholds are found not enough for this kind of mountain highways. The goal of this paper is to find an optimization design method for combination of steep slope and sharp curve sections based on the analysis of vehicle driving stability. The overall safety model of steep slope and sharp curve combined section is established, and the relevant coordination relationship between design indices of the front and rear alignment unit is established by using the operating speed estimation model. Taking the maximum slope length corresponding to the specified design speed as the design condition of the front segment, the threshold values and variation rules of the design indices of the rear segment under different design speeds are calculated ensuring driving safety. The safety model is simulated by CarSim software, the trajectory offset and lateral acceleration are used to indirectly reflect the degree of lateral instability, and the results are compared to verify the effectiveness of the simplified safety model established in this paper.

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“…It was observed that curve radii of 400 m and higher have an insignificant effect and radii above 800 m have no effect on vehicle operating speed [3,4]. Furthermore, the effect of a horizontal curve on vehicle operating speed is significant in flatter gradient [5]. Horizontal curve radius is the most common independent parameter in the operating speed prediction models at MC [3,[6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…However, these studies are based on traffic with stronger lane discipline. Nama et al [5] extensively studied the speed characteristics of passenger car and heavy commercial vehicle with weak lane discipline but did not provide a speed prediction model. On the other hand, Sil et al [15] developed the speed prediction model for passenger cars at MC only.…”

Section: Introductionmentioning

confidence: 99%

Speed prediction models for car and sports utility vehicle at locations along four-lane median divided horizontal curves

Maji

Tyagi

2018

J. Mod. Transport.

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Sites with varying geometric features were analyzed to develop the 85th percentile speed prediction models for car and sports utility vehicle (SUV) at 50 m prior to the point of curvature (PC), PC, midpoint of a curve (MC), point of tangent (PT) and 50 m beyond PT on four-lane median divided rural highways. The car and SUV speed data were combined in the analysis as they were found to be normally distributed and not significantly different. Independent parameters representing geometric features and speed at the preceding section were logically selected in stepwise regression analyses to develop the models. Speeds at various locations were found to be dependent on some combinations of curve length, curvature and speed in the immediately preceding section of the highway. Curve length had a significant effect on the speed at locations 50 m prior to PC, PC and MC. The effect of curvature on speed was observed only at MC. The curve geometry did not have a significant effect on speed from PT onwards. The speed at 50 m prior to PC and curvature is the most significant parameter that affects the speed at PC and MC, respectively. Before entering a horizontal curve, drivers possibly perceive the curve based on its length. Longer curve encourages drivers to maintain higher speed in the preceding tangent section. Further, drivers start experiencing the effect of curvature only after entering the curve and adjust speed accordingly. Practitioners can use these findings in designing consistent horizontal curve for vehicle speed harmony. Keywords Vehicle speed prediction model Á Four-lane median divided highway Á Horizontal curve Á Regression analysis Á The 85th percentile speed

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Vehicle Speed Characteristics and Alignment Design Consistency for Mountainous Roads

Cited by 37 publications

References 13 publications

Operating Speed Prediction Model as a Tool for Consistency Based Geometric Design of Four-Lane Divided Highways

Operating Speed Prediction Model as a Tool for Consistency Based Geometric Design of Four-Lane Divided Highways

An Optimization Design Method of Combination of Steep Slope and Sharp Curve Sections for Mountain Highways

Speed prediction models for car and sports utility vehicle at locations along four-lane median divided horizontal curves

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