To handle the project efficiently, Hanson uses a combination of GIS and mobile 
mapping technologies. According to Hanson Assistant Vice President Gary 
Rogers, PLS, the firm used GIS technology to capture and manage positions 
of the signs. The GIS also contained photos and permitting information. 
Some information, such as permit tag numbers, could only be obtained by 
visiting each sign. Other data including sign dimensions, milepost and offset 
from centerline could be better handled using mobile mapping. Together, 
the two technologies could check and supplement one another, enabling 
Hanson to set up the sign database for subsequent years.

In the first year of the project, Hanson conducted field surveys at each sign 
to develop an accurate baseline inventory of the actual conditions in the 
field. Hanson equipped its in-house and contract field technicians with 
Trimble GeoXH™ handheld GPS receivers. At each sign, the technician 
collected specified information including GPS position and digital photos 
as well as the sign’s permit number, type, and condition. According to Rogers, 
each technician could visit and collect information on roughly 50 or more 
signs on a typical day. Each day’s data were downloaded and sent to 
Hanson’s office for checking and processing. The results were then added 
into an Esri ArcGIS geodatabase.

To verify the information, Hanson compared the GIS data from the field sur-
veys of the signs against independent measurements. For this, Hanson used 
a Trimble MX1 Mobile Data Capture System to rapidly obtain high-quality 

acquisition of position and images, and other 
data not collected by the field crews, along the 
state's controlled highways. Following routes 
designed by Hanson’s GIS staff, Hanson’s 
mobile mapping vehicle could collect data on 
roughly 400 mi (640 km) per day at intervals 
of 10 m (33 ft). Over the course of two years, 
Hanson collected data along more than 
35,000 mi (56,000 km) of highway. 

At the end of each day, the mobile data were 
transferred to Hanson’s office in Springfield.  
Using Trimble Trident Analyst software, techni-
cians inspected each photo to extract sign 
position and information including sign face 
dimensions, structure type, and distance from 
the highway centerline. The completed infor-
mation was combined with the field GIS data. 

Rogers is convinced that using multiple Trimble 
technologies is key to the project’s success. 
“The data collection resulted in a robust inven-
tory of controlled signs and their locations 
that were then compared with IDOT’s permit 
database,” he said. “We can rapidly review any 
changes to the inventory for compliance with 
the State’s Highway Advertising Control Act.”  

Using the Trimble MX1 to confirm the field 
data was essential in meeting the project 
goals and produced significant savings in time 
and costs. At the end of the first year of the 
contract, Hanson had completed and verified 
the entire IDOT sign inventory. The information 
was added to the state database, where signs 
can be compared with existing permits to 
identify discrepancies or illegal signs. During 
the subsequent years of the contract, Hanson 
will use the Trimble mobile mapping system 
to detect changes or newly constructed signs 
in the field. 

The technology provides benefits beyond 
the financial aspects. The mapping systems 
eliminated the need for field personnel to stop 
and work along the state’s busy highways. 
This resulted in lower risk of accidents and in-
creased comfort and safety for the field teams. 
“It’s an incredibly important tool,” Rogers con-
cluded. “We can collect high-quality data while 
moving at highway speeds. It’s fast, safe and 
accurate. ”The next time you travel on Route 
66, remember that mobile mapping is helping 
to keep America’s scenery in view.

See feature article in Professional Surveyor's 
March issue: www.profsurv.com