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Innovative applications
Published in Malcolm D. Bolton, Akio Kitamura, Osamu Kusakabe, Masaaki Terashi, New Horizons in Piling, 2021
Malcolm D. Bolton, Akio Kitamura, Osamu Kusakabe, Masaaki Terashi
Common problems encountered in the Road–Road grade separation in a densely built urban environment are: a limited right-of-way, restriction of construction time and space, special care for minimizing any adverse influence on the current traffic volume during construction, and noise and vibration. Grade separation can be achieved by depressing the major road with the larger traffic volume underneath minor roads with less traffic, thereby permitting through traffic on the major road to travel without traffic signals as exemplified in Figure 3.19. By employing embedded walls for the retaining walls of the depressed road and for the foundation of the bridge structures of the at-grade road, the construction sequence is simplified and space required for construction is minimized by the use of the walk-on-pile-type press-in piling.
Foundational elements of the IPD Collaboration Framework
Published in Derek H. T. Walker, Steve Rowlinson, Routledge Handbook of Integrated Project Delivery, 2019
Derek H. T. Walker, Beverley Lloyd-Walker
Socially oriented project-owner organisations tend to see value, and hence BV, in terms of a balance of tangible amenity or facilities that have an active purpose combined with an intangible form of value. There is a program of work being undertaken in Melbourne at the time of writing for the removal of 50 level crossings, the Level Crossing Removal Program (LXRP). This program of work is expected to deliver multiple layers of value. Firstly, and more tangibly, it is aimed to provide grade separation, between trains and traffic (pedestrian as well as vehicular), in a cost-effective manner. Rail lines may be relocated to remove the level crossing in a below-road-grade-level trench with a bridge over the track or as a ‘sky-train’ stretch of rail line elevated above the former track.
Economic analysis of mobility improvements
Published in Zongzhi Li, Transportation Asset Management, 2018
Grade separations: Intersections that handle high volumes of vehicular and pedestrian traffic (and in some cases rail traffic) limit the capacity of the approaching roads. Grade-separating these points of conflict allows uninterrupted traffic flow while also eliminating the safety threat posed by crossing traffic. Three primary roadway improvement objectives are accomplished using grade-separated intersections: (i) increased capacity and uninterrupted flow; (ii) increased safety; and (iii) reduced auto-train conflicts and delays. Grade separation can be implemented for high-volume roadway intersections or highway-railroad crossings. Grade-separated intersections are expensive to build, thus they should be used only when other techniques such as signal timing and lane additions are unsuccessful in reducing congestion to an acceptable level or were impossible due to external constraints. Grade separation works well when one or more directions continue to experience heavy traffic and high congestion even after other methods have been exhausted.
Selection of at-grade highway-rail crossings for grade separation
Published in International Journal of Rail Transportation, 2023
Xue Yang, Joshua Q. Li, Wenyao Liu, Kelvin C. P. Wang, Jim Hatt, Jared Schwennesen
With the ambitious goal of zero deaths but increasing traffic and congestion at grade crossings, states and communities are increasingly promoting grade separation as a viable alternative that not only improves safety but also boosts network capacity and improves liveability [7]. The grade separation of these conflict points allows for continuous traffic flow while also eliminating the safety threat posed by trains, pedestrians, and/or other vehicles. However, the costs of highway-rail grade separation projects are expensive and can vary considerably depending on the surrounding environments (rural versus urban), the number of lanes and/or tracks, and the design of the proposed separation. According to a statewide study by the Minnesota Department of Transportation (MnDOT), the costs of grade separation improvements could range from $10 million for a rural two-lane road to nearly $50 million for urban multiple-lane construction [8].
Progress in pedestrian safety research
Published in International Journal of Injury Control and Safety Promotion, 2020
One of the earliest study on pedestrian crashes (Waller, 1985) reported ‘Pedestrians are often asked to decide between the easy and quick way to safe way’. Repeated empirical studies have shown that pedestrians chose the former. Often grade separation between pedestrian and vehicular movement has been suggested in urban areas as well as on highways in LMICs to improve pedestrian safety. This involves constructing foot over bridges or underpasses. Empirical studies have been carried out in different regions and settings to understand pedestrian behaviour at zebra crossings at grade, foot over bridges and under passes. Cantillo, Arellana, and Rolong (2015) reviewed a large number of studies on pedestrian crossing behaviour in urban environments and concluded that pedestrian crossing behaviour is affected by socioeconomics (e.g., age, gender), traffic characteristics (e.g., speed and flow), the road environment (e.g., crossing walking distance, presence of traffic/pedestrian control devices and signals, presence of crossing facilities), and subjective factors (e.g., perceptions and attitudes). This study found that additional walking distance to cross the road over the pedestrian bridge is less appealing than using a zebra when available; even if it is less attractive when compared to crossing directly somewhere on the road. This effect could be explained by the additional effort needed to climb and descend stairs in a pedestrian bridge. Cantillo et al. (2015) reported that ‘the respondents state a general dislike to walk additional distances to cross the street using the “safer” alternatives (i.e., pedestrian bridge and crosswalk at the intersection). To some extent, respondents prefer to walk towards an intersection rather than going towards a pedestrian bridge to cross’. Model results suggest that pedestrians are willing to take less risk when traveling with a minor. The presence of a minor increases the probability of using safer crossings; in fact, the direct crossing alternative became less attractive. The probability of being delayed also has an important effect on the decision. Pedestrians are more prone to use the alternative route involving less walking distance (crossing directly). The authors concluded that ‘…a largest distance diminishes the probability for the individual to choose safer alternatives. It is observed that this effect is more relevant for the case of the pedestrian bridge than for the signal crossing, which may be explained by the extra effort involved in climbing stairs. This finding suggests that pedestrian bridges should only be considered in extreme cases, as they seem to be a non-effective crossing facility. To solve conflicts between traffic and pedestrian flows it is preferable to propose at level signalized crossings along with underpass/overpass roads, when necessary’.