Abstract: A roadway expansion that takes place on soft ground is susceptible to differential settlement because of the high consolidation of
soft soils. Therefore, steps must be taken to lessen the risk of such settlement; yet, this often only results in costly drainage solutions. In that,
applying a systematic value engineering (VE) process can be beneficial to develop cost-effective design alternatives. However, VE studies
specifically targeting for this problem are absent from the field. Thus, the goal of this study is to supplement this knowledge gap by applying a
systematic VE process to an expansion project on soft ground to demonstrate the benefits of performing VE. A case study was performed on
an expansion project over a soft soil layer approximately 50 m thick. Through the VE process, the original design was reviewed, problems
were discussed, and three alternatives were proposed. Then value analysis techniques were applied to evaluate these alternatives in terms of
cost saving, function improvement, and value improvement with respect to the original design. The VE process and design alternatives as
applied in this study are expected to serve as a guideline for engineers and decision-makers in roadway expansion projects on soft ground.
DOI: 10.1061/(ASCE)CO.1943-7862.0001054. © 2015 American Society of Civil Engineers.
Author keywords: Value engineering (VE); Job plan; Roadway expansion; Deep soft ground; Differential settlement; Value improvement;
Cost saving; Project planning and design.
Introduction
In 2011, the number of vehicles worldwide surpassed 1 billion
units—an annual increase of 3.6%, 20 million vehicles, since 2009
(WardsAuto 2011). Today, increased traffic continues to demand
road expansions internationally, and these expansions require adequate planning to minimize the chance of differential settlement
between new and existing sections. When an expansion project
occurs on soft soils specifically, the embankment for new sections
could cause high settlement because of the high consolidation
of soft soils, which subsequently leads to differential settlement
between the new and existing road. Such differential settlement
can result in a number of problems such as reduced traffic safety
and reduced structural stability, increased surface cracking, and increased maintenance costs during construction and maintenance.
In recent years, ground improvement methods based on drainage systems have proven effective for accelerating the consolidation of soft soils. Unfortunately, such drainage systems are typically
costly. Therefore, applying a systematic value engineering (VE)
process can be beneficial in developing cost-effective design alternatives that can improve the value of expansion projects on soft
ground, while effectively mitigating the risk of differential settlement. However, no identified VE study has aimed at developing
design solutions for a roadway expansion on soft ground. In
response, the overarching goal of this study is to supplement this
knowledge gap by applying a systematic VE process to a case
project to exemplify the process of developing design alternatives
for a roadway expansion on soft ground. To achieve the goal, this
study aims: (1) to analyze the original design of a roadway expansion project for brainstorming ideas for improvement; and (2) to
synthesize and evaluate ideas for developing alternatives as design
improvement through a systematic VE process, called the job plan.
To exemplify the VE process as applied in a roadway expansion
project, a highway expansion project in South Korea was selected.
It is expected that the VE process as applied in this study, along
with the design alternatives developed as a result of the process,
will provide a guideline for engineers and decision-makers to
perform VE when they face issues related to a roadway expansion
project on soft ground. It is also believed that the rigor of this case
study will provide insight and evidence regarding the capability
and effectiveness of the VE job plan in improving the value of expansion projects.
Literature Review
Geotechnical Issues Related to Expansion Projects on
Soft Ground
It is a geotechnical fact that stress can exist at a point in soils
not only because of a superstructure loading above the point,
but also by loading on adjacent points (Bowles 1997; Clough
and Woodward 1967). When applied to saturated clay, this stress
can result in consolidation because of dissipation of excess pore
water pressure (Bergado et al. 1990; Holtz and Kovacs 1981). This
localized differential settlement can cause unevenness and cracking
in the road, and even cracks in a superstructure itself (Ludlows et al.
1993; Varin and Saarenketo 2012). Applying uniform embankment
preload to the entire roadway area for an extended period will
create uniform settlement and thus minimize the likelihood of this
1
Professor, Dept. of Civil Engineering, Korea Maritime and Ocean
Univ., Busan 606-791, Republic of Korea. E-mail: kth67399@kmou.ac.kr
2
Assistant Professor, Dept. of Construction Management, Univ. of
Washington, 120 Architecture Hall, Campus Box 351610, Seattle, WA
98195 (corresponding author). E-mail: hyunwlee@uw.edu
3
Assistant Professor, Dept. of Civil Engineering, Dong-Eui Univ., 176
Eomhwangno, Busan-Jin-gu, Busan 614-714, Republic of Korea. E-mail:
hongswoo@deu.ac.kr
Note. This manuscript was submitted on December 29, 2014; approved
on July 10, 2015; published online on August 17, 2015. Discussion period
open until January 17, 2016; separate discussions must be submitted for individual papers. This paper is part of the Journal of Construction Engineering and Management, © ASCE, ISSN 0733-9364/05015014(9)/$25.00.