Providing traffic management services is one
of PB’s responsibilities in our role as prime civil engineering
consulting firm on the Dallas-Fort Worth International Airport (DFW)
Development Team. This activity consists primarily of designing
and coordinating all traffic control plans to support DFW’s
Capital Development Program (CDP). It is a large effort, given that
the airport occupies 7200 ha (18,000 acres), which is approximately
the size of Manhattan Island in New York.
The DFW CDP is an ambitious $2.6 billion five-year program that
is highlighted by a new automated people mover and a new International
Terminal D, construction of which will dynamically impact the existing
DFW landside roadway system. This system provides vital access for
airport customers traveling to or from each of the airport terminals
and all airport related support services, and it serves as a regional
roadway for the Dallas/Fort Worth urban area. As such, it is imperative
for DFW to maintain the existing limited roadway capacity while
this construction program is underway.
Figure 1: Traffic Management Master
Plan |
We have approached this challenge by developing
a Traffic Management Master Plan as shown in Figure 1. This plan
consists of the following:
- Benchmarking
- Planning
- Design
- Operation and deployment
- Traffic information services
- Evaluation of performance measures.
Benchmarking
During the benchmarking phase, when existing conditions are established
to compare against future performance, our team collected existing
roadway information to be used during the traffic control design
and implementation process. We also inventoried, analyzed, and digitally
photographed all existing landside roadway traffic signals to determine
what features were available in case we needed to provide revised
phasing or timing patterns to accommodate construction. All existing
landside roadway traffic control devices, (including traffic signals)
were located to provide the traffic control plan design engineer
with existing signs, signals, crash attenuators, etc. so the engineer
could determine if any were in conflict with the proposed plan or
needed to be removed or covered during the implementation of a specific
plan. The devices were inventoried by DFW surveying staff using
GPS equipment to collect x- and y-coordinates, sign dimensions and
elevation measurements, and digital photographs were taken to provide
a record for future traffic control planning and design. Our staff
developed a Microsoft Access® database containing
all of this information and converted it into an ArcView®
shape file to provide quick point-and-click access capabilities.
We subcontracted with two local traffic-counting firms to collect
turning movement counts at existing and proposed traffic signal
locations identified by airport staff. Twenty-four hour directional
counts were collected on airport landside roadways expected to be
impacted by the construction.
Dallas-Fort Worth International
Airport |
Planning
Our staff then took all of the traffic count data and developed
a landside roadway traffic simulation model using a traffic engineering
industry standard model. Initially we proposed using the FHWA CORSIM
model for this analysis. Upon further investigation of the existing
DFW roadway network, however, we saw that the intersection geometry
for the subject roadway, in particular the left turn movements around
underpasses, were not similar to the typical intersection layouts
to be modeled with CORSIM. We determined that Synchro would be the
better simulation model to use because of the roadway operational
characteristics and the signal operations. In additional, Synchro
provides a dual capability of signal timing optimization and simulation
within the same package. This model was used as an evaluation tool
for multiple construction work zones that impacted the airport landside
roadway system at the same time.
Design
Our staff is responsible for designing all traffic control plans
that support each of the CDP projects. If each project is taken
individually, this task is somewhat routine. Due to the aggressive
timeline of DFW’s CDP schedule, however, this was not the
case. It is our responsibility to coordinate each and every project
to ensure that one project does not close a lane needed by another
project.
The design and implementation of these plans must take into consideration:
- Any DFW tenant construction activity
- Local utility construction activity
- DFW maintenance activity
- The continual provision of ingress
and egress into each of the four terminals and three remote parking
areas.
PB is an active participant in the design and
construction coordination meetings among the other design firms,
contractors, and airport staff, and we provide leadership by representing
traffic control needs in establishing the overall construction schedule.
Operation and Deployment
DFW Airport Development has retained one contractor who is responsible
for implementing all traffic control plans. To date, these plans
have involved the use of standard work zone traffic delineation,
signing, dynamic message signs, arrow boards, and a temporary video
camera installation to maintain side street actuation at a traffic
signal during construction.
DFW requires our design engineer to be on site during the first
night’s implementation of all major roadway shutdowns and
traffic detours (which are allowed only between 9:30 p.m. and 5:30
a.m.) of each plan in case something unexpected arises. This process
becomes challenging when multiple plans need to be implemented at
the same time.
Figure 2: Peak Period Speeds on
DFW Airport Roads |
Performance Measures
We provide an independent quality assurance inspection to assure
that each traffic control plan or multiple traffic control plan
scenario is implemented per plan and provides for consistent and
positive traffic flow. This quality assurance inspection checks
the implementation against the design plans, requirements of the
Texas Manual of Uniform Traffic Control Devices, and industry wide
work zone device implementation. Any discrepancies or problems are
noted and reported to our design engineer and the DFW traffic engineer
for correction.
We also monitor the impacts of implementing the plans by conducting
monthly travel time runs. International Parkway, the main expressway
through the airport, carries nearly 50,000 vehicles per day and
the service roads that run parallel to International Parkway carry
nearly another 50,000 vehicles per day. Peak period speeds along
the service roads are shown in Figure 2 on the previous page. Even
though several traffic control plans have been implemented that
impact these roads, level-of-service has remained high during peak
times.
Traffic Information
The last part of the cycle is getting information to the public
and improving traffic control planning and design through monitoring
performance. Weekly traffic control maps showing location and scope
of the work zones are posted to the DFW Web page. Both airport employees
and the general public can view work zones that may impact travel
by going to the airport’s Web site (see Related Web site,
below) and choosing the traffic control map in the box on the right.
Our team develops the weekly map based on information received from
all CDP contractors every Monday morning. We then forward the map
to DFW’s marketing department, where it is converted to a
Web image. The traffic map can be referenced as a tool (both the
paper and electronic version) to widely disseminate weekly traffic
control information to airport users and staff.
Keys to a Successful Program
Our wealth of knowledge in geometric design principles and experience
in traffic control work zone design and traffic engineering operations
helped tremendously to make this program successful. Throughout
this process, however, several important lessons have been learned:
-
The traffic control contractor chosen to implement the designed
plans must have past experience in the sound principles of safe
traffic control implementation and maintenance.
- The contractor must be capable of managing
multiple work zone implementations at the same time, while balancing
the time requirements of the individual construction contractors,
and DFW ground operations and maintenance staff.
- It is very important that the traffic control
plan design engineer attend all contractor, sub-contractor, owner,
and traffic management planning meetings in order to provide appropriate,
accurate, and timely traffic control plans to maintain the ambitious
fast paced construction schedule of the DFW CDP.
- Daily communication between the design
engineer, the contractor, other CDP contractors, the work zone
implementation contractor, and DFW staff was an essential factor
in providing and implementing an effective traffic management
plan.
Keeping the traveling public moving and safe
while providing the contractor with sufficient work zone area for
worker safety and efficiency measure the success of the program.
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