Developing a Safer Impact-Absorbing Street Lighting Pole for Urban Environments and Review of Test Requirements and Pass–Fail Criteria

摘要

According to Australian Road Transport Statistics, every third accident is a single-vehicle accident and involves a collision with a roadside object, such as trees, utility poles, bridge fences, buildings, and others. Therefore, it is important to improve the performance of roadside street furniture in order to reduce the road toll. This paper presents an overview of the development process for a new safer impactabsorbing street lighting pole (IASLP) using a dual crumple zone. There are two types of frangible street light poles used in Australia: slip-base street light poles (SBSLP) and IASLP. The SBSLP is commonly used in outer metropolitan areas where there is minimal or no pedestrian traffic. Its mode of operation is to detach and provide minimum resistance to an impacting out-of-control vehicle. Due to this breakaway feature, the impacting vehicle deceleration is low and could result in no injuries to the vehicle occupants. On the other hand, the IASLP is predominantly used in inner-metropolitan areas, where pedestrian traffic is significant and a probability of injuring pedestrians by the falling pole is high. The IASLP is designed to deform and absorb energy during impact. It should stay attached to the pole base, safely arrest the vehicle, and not harm its occupants. The IASLP must deform progressively and in a predictable manner so it does not present danger to the pedestrians or other road users. There are two types of footing for IASLP: in ground and base plate mounted. This paper deals with base plate-mounted IASLP which is preferred by some road authorities for maintenance reasons. The IASLPs have been used on Australian roads for more than 20 years and some have been tested using an average Australian car with a mass of 1,200 kg and traveling at 60 km/h. This type of IASLP has only one crumple zone, optimized for one impact energy level. In line with changing crash testing requirement for other road safety hardware such as crash cushions or road barriers, it was important to advance towards more-realistic and more-effective designs, utilizing smaller vehicles at lower speeds and heavier vehicles at higher speeds. A dual crumple zone pole has been developed in response to this requirement. Moreover, to improve shear strength of this pole, the column at the base has been reinforced and to produce safer response to vehicle impact, the base plate has been lowered underground. While developing this new design for IASLP, testing authorities in Australia and overseas appear to have different interpretations of the pass–fail criteria, which may lead to acceptance of unsafe designs. The intention of this paper is to propose a new test matrix and evaluation criteria of tests results as well as to present a number of critical design changes for the new safer IASLP. INTRODUCTION Road crashes represent a large human and financial burden to Australian society. Since record keeping in 1925, there have been more than 180,000 deaths on Australia’s roads. The annual economic cost of road crashes is estimated to be $27 billion per annum and the social consequences are devastating. Although the road trauma levels have declined substantially over the last four decades the road death toll is still significant: it was 3,798 in 1970 and 1,192 in 2013 (1). Approximately 1/3 of these fatal accidents involve fixed-roadside objects. A safer IASLP has the potential to make a significant contribution to the reduction of the Australian road toll. Specifically, the IASLP function is to protect two groups of road users in an event of road accident—vehicle occupants (driver and passengers) and other road users (pedestrians and other road traffic). TESTING AND EVALUATION The initial project objectives include the following: 1. To define a suitable test matrix and 2. To define the test evaluation and pass–fail criteria. The proposed test matrix has been changed from currently accepted 1,200-kg sedan ve