Towards Green Bridges

摘要

There is no existing standard to define a green bridge. Green standards have been successfully implemented in other industries and can be used as a guide for developing a green standard for bridges. The goals of green design include reducing greenhouse gas emissions, pollution emissions, waste, energy, and the use of non-renewable resources to sustainable levels.rnThe Greenbridges standard proposed herein has a total of six prerequisites and thirty-nine points grouped into seven categories. The categories are: materials & resources, alternative transportation, project delivery process, construction activity, maintenance & access, environment & water, and energy. Greenbridges is a tool that will encourage existing best practices to see more widespread use.rnTwo primary strategies for "greening" bridge projects are to maximize the use of recycled and by-product materials and to design for minimum life cycle costs.rnConcrete made with high percentages of by-product pozzolan cements, in place of Portland cement, have greatly reduced greenhouse gas emissions and embodied energy. Recent bridge projects have used concrete mixes with as much as 85% pozzolan cements.rnBridges with lower life cycle costs will tend to be "greener". In other words, the least expensive bridge alternative is also likely to have the least associated emissions and embodied energy. The key is to consider the total costs for design, construction, use, maintenance, demolition, and salvage; not solely initial construction cost.