Estimating the Safety and Operational Impact of Raised Medians and Driveway Density: Experiences from Texas and Oklahoma Case Studies

Eisele, William L; Frawley, W E

doi:10.3141/1931-14

Cited by 23 publications

(21 citation statements)

References 2 publications

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“…Some simulation-based studies have considered the access density as an essential and easily controllable parameter in the simulation model. The results revealed that access density strongly influences the TWLTL performance; generally, higher access density results in higher crash rates (Eisele and Frawley 2005) and lower average travel speed .…”

Section: Introductionmentioning

confidence: 93%

“…This is because geometric factors such as access density are uncontrollable variables for field observation. Studies based on simulation software such as CORSIM Giese et al 2001), TRAF-NETSIM (Venigalla et al 1992), and VISSIM (Eisele and Frawley 2005) do exist, though not many. Some simulation-based studies have considered the access density as an essential and easily controllable parameter in the simulation model.…”

Section: Introductionmentioning

confidence: 97%

“…Since the mid-1980s, studies have shifted focus to a comparison between the efficiency and safety of a TWLTL and a nontraversable median (Venigalla et al 1992;Mukherjee et al 1993;Margiotta and Chatterjee 1995;Bonneson 1997;Phillips et al 2004;Eisele and Frawley 2005;Kaseko and Mauga 2010) because both are usually used as improvements to four-lane undivided roadways having operational and safety problems. Some studies also analyzed four-lane undivided roadways (Harwood 1986(Harwood , 1990Bonneson 1997).…”

Section: Introductionmentioning

confidence: 98%

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Investigation of the performance of two-way left-turn lane on roads with staggered intersections

WuZhizhou

2014

Can. J. Civ. Eng.

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A simulation based on VISSIM and its external driver model dynamic link library (DLL) was used to investigate the efficiency and safety of a two-way left-turn lane (TWLTL) on roads with staggered intersections (SIs). The impacts of traffic volume, ratio of left-turn vehicles, and stagger distance on SIs and conventional cross intersection (CI) were simulated with the following results: (1) SIs with stagger distance shorter than 200 m show few advantages in terms of average delay over a CI irrespective of traffic volume and left-turn ratio; (2) In contrast, SIs with stagger distance longer than 200 m show advantages that, however, disappear with an increase in traffic volume and left-turn ratio; and (3) SIs show a significantly higher number of traffic conflicts than CIs, indicating that they have more serious safety problems. These results should help traffic researchers and practitioners decide whether it is feasible to establish SIs on existing roadways with TWLTLs and the appropriate stagger distance for SIs, as well as whether it is appropriate to change a road that has dense SIs into a TWLTL cross section.Résumé : Une simulation a été réalisée à partir du logiciel VISSIM et de sa bibliothèque de liens dynamiques (dynamic link library ou DLL) associée au modèle de conducteur externe pour étudier l'efficacité et la sécurité des tourne-à -gauche à double sens (TGDS) sur les routes comportant des intersections décalées (ID). Les répercussions de ces aménagements sur le volume du trafic, la proportion de véhicules tournant à gauche et la distance de décalage aux ID et aux carrefours conventionnels (CC) ont été simulées et ont donné les résultats suivants : (1) Les ID avec distance de décalage inférieure à 200 m présentent peu d'avantages en termes de temps moyen d'attente par rapport aux CC, quel que soit le volume du trafic et la proportion de véhicules tournant à gauche; (2) À l'inverse, les ID avec distance de décalage supérieure à 200 m présentent des avantages qui disparaissent néanmoins lorsque le volume du trafic et la proportion de véhicules tournant à gauche augmentent. (3) Il y a beaucoup plus de conflits de circulation aux ID qu'aux CC, ce qui signifie que les ID posent des problèmes de sécurité plus graves. Ces résultats devraient aider les chercheurs en circulation et les professionnels de ce domaine à déterminer si l'aménagement d'ID sur des routes existantes comportant des TGDS, avec la distance de décalage appropriée, est réalisable et s'il est pertinent de transformer une route comportant des ID à forte densité de circulation en un carrefour équipé de TGDS. [Traduit par le Rédaction]Mots-clés : tourne-à -gauche à double sens, intersection décalée, efficacité, sécurité.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

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Investigation of the performance of two-way left-turn lane on roads with staggered intersections

WuZhizhou

2014

Can. J. Civ. Eng.

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“…Access management is a process that controls physical access to developed land while simultaneously preserving traffic safety, mobility, and speed (Demosthenes 1999;Eisele and Frawley 2005;Gattis 2005;Gattis, Balakumar, and Duncan 2005;Gluck, Levinson, and Stover 1999;Gluck et al 2005;Koepke and Levinson 1992;Rose et al 2005;Stamatiadis et al 2004;Stokes, Russell, and Vellanki 1994;Transportation Research Board 2003). Strategies include removal of access/service points by closing median openings, frontage road access for business driveways, special turning lanes to separate through vehicles from turning vehicles, and proper signing and pavement markings to communicate access points to drivers (Garber and Hoel 2002).…”

Section: Introductionmentioning

confidence: 97%

Risk management for infrastructure corridors vulnerable to adjacent land development

Linthicum

Lambert

2010

Journal of Risk Research

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Communities worldwide face diminished infrastructure performance and increased operating and capital costs resulting from unmanaged industrial, commercial, and residential development that impinges on their infrastructure corridors. It is important that planners anticipate and proactively manage land development along the corridors to avoid surprise, regret, and belated action. This paper demonstrates an approach utilizing expert elicitation and geographic data (i) to assess the relative risk of land development adjacent to infrastructure corridors, and (ii) to focus and prioritize corridor sections for risk management. The approach uses several factors to score adjacent properties according to their relative likelihoods of development in a 10-to 20-year horizon. The scores are compared to land values and existing road-access points in order to illuminate the relative costs of risk management along corridor centerlines. The riskmanagement options, including land acquisition, negotiation with developers, and limitations on future access points, are discussed. The approach is germane for risk-based protection of infrastructure corridors of both developed and developing regions of the world, for a range of time horizons, geographic scales, and infrastructure networks.

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“…This FDOT policy was based on earlier study results showing the benefits of raised medians, as compared with TWLTLs. Several studies over the past two decades documented a reduction in crash rate after arterials with TWLTLs were converted to raised medians (Maze and Plazak 1997, Gattis et al 2005, Parsonson et al 2000, Eisele and Frawley 2005. However, results from some more recent studies (for example, Phillips 2004, Schultz et al 2007 showed an increase in crash rates after conversion from TWLTLs to raised medians.…”

Section: Introductionmentioning

confidence: 99%

Safety Impacts of Converting Two-Way Left-Turn Lanes to Raised Medians and Associated Design Concerns

Alluri¹,

Gan²,

Haleem³

2016

J Transp Res Forum

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Raised medians and two-way left-turn lanes (TWLTLs) are the two most common types of median treatments on arterial streets. This paper aims to conduct a detailed study on the safety impacts of conversion from TWLTLs to raised medians on state roads in Florida. In addition, the study also investigated several potential safety concerns related to raised medians on state roads, including crashes at median openings, vehicles directly hitting the median curb, and median crossover crashes. Based on data availability, 17.51 miles of urban arterial sections in Florida that were converted from TWLTLs to raised medians were analyzed. Police reports of all the crashes before and after median conversion were reviewed to correct miscoded crash types and obtain additional detailed crash information. Overall, a 28.5% reduction in total crash rate was observed after the 10 study locations were converted from TWLTLs to raised medians. The reductions in the proportions of left-turn and right-turn crashes were statistically significant, while the changes in the proportions of other crash types were not statistically significant. Furthermore, the crash data did not show evidence that raised medians are an additional hazard compared with TWLTLs.

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Estimating the Safety and Operational Impact of Raised Medians and Driveway Density: Experiences from Texas and Oklahoma Case Studies

Cited by 23 publications

References 2 publications

Investigation of the performance of two-way left-turn lane on roads with staggered intersections

Investigation of the performance of two-way left-turn lane on roads with staggered intersections

Risk management for infrastructure corridors vulnerable to adjacent land development

Safety Impacts of Converting Two-Way Left-Turn Lanes to Raised Medians and Associated Design Concerns

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