Improving Safety through Pennsylvania’s

Intersection Safety Implementation Plan (ISIP) 

Introduction 

According to the 2012 Pennsylvania Strategic Highway Safety Plan (SHSP), nearly 40 percent of all traffic 

crashes in the State occur at intersections. These crashes account for approximately one-quarter of the total 

fatalities and major injuries1. In Pennsylvania, intersection safety has been a safety priority since 2006 and has 

been included in previous iterations of the SHSP. One of the top strategies identified in the SHSP for 

improving intersection safety is the Intersection Safety Implementation Plan (ISIP). 

The development of the ISIP began in 2009 when the Federal Highway Administration held a workshop 

assembling safety personnel from the Pennsylvania Department of Transportation (PennDOT) and Local 

Technical Assistance Program to identify safety initiatives in the intersection emphasis area of the SHSP. The 

results of the workshop led to a consensus on a set of countermeasures, deployment levels, and costs. 

PennDOT released the ISIP in February 2010. The plan included expanding the traditional approach of 

implementing moderate-cost improvements at the highest crash locations to include the addition of a 

systemic approach of deploying a large number of low-cost countermeasures at intersections with crashes 

above a defined threshold.

Process and Results 

Although PennDOT developed and 

released the ISIP in 2010, the plan was 

not implemented until 2014, when onethird of the Highway Safety 

Improvement Program (HSIP) funding 

was set aside for intersection and 

roadway departure improvements. 

PennDOT was successful in developing 

and implementing the ISIP because the 

plan was ingrained in the HSIP policies 

and procedures for funding. The central 

office reviewed HSIP applications. Then, 

it was the responsibility of the districts to 

deliver the projects. Because PennDOT 

is a decentralized agency, it provided the 

districts with guidance on implementing the countermeasures outlined in the ISIP. Using the systemic 

approach allowed PennDOT to complete projects that were low-cost, improved safety quickly, and had 

limited right-of-way impacts. 

 

1

 PennDOT. 2012. Strategic Highway Safety Plan. Pennsylvania Department of Transportation, Harrisburg, Pennsylvania. 

Signage and pavement marking upgrades. 

 Source: PennDOT.
FHWA-SA-16-082 

Revised June 2020

Countermeasures 

Below are some examples of systemic countermeasures implemented for signalized and stop-controlled 

intersections identified in the ISIP that had the highest deployment levels, along with the associated 

construction costs: 

 Basic Set of Sign and Pavement Marking Improvements:

o State intersections: 1,072 intersections for $8.58 million.

o Local intersections: 114 intersections for $910,000.

 Basic Set of Sign and Signal Improvements:

o State intersections: 353 intersections for $10.59 million.

 Change of Permitted and Protected Left-Turn Phasing to Protected-Only:

o State intersections: 276 intersections for $1.38 million.

 Pedestrian Enhancements:

o State intersections: 477 intersections for $14.2 million.

 Speed Reduction Enhancements:

o State intersections: 535 intersections for $8.02 million.

The current ISIP has identified improvements for 

over 3,000 intersections representing an investment 

of $56 million—or approximately $11 million 

annually over five years—to fully implement the 

plan. These figures will change when the State 

officially updates its ISIP. PennDOT recently 

awarded more HSIP funds for future ISIP projects. 

Expected Outcome 

Because of the successful countermeasure 

implementation at the intersections identified by the 

ISIP, the project lists for the district offices are 

becoming short. The local agencies and districts are 

currently looking to identify new priority locations and best practices for updating the project list. PennDOT 

will begin evaluations of the ISIP improvements once three years of after data are available. Since 

Pennsylvania has its own regional safety performance functions for segments and intersections, the State is

also exploring the methodologies in the Highway Safety Manual for prioritizing sites for implementation. 

Contact 

Federal Highway Administration

Pennsylvania Division Office

717.221.3461

Pennsylvania.FHWA@dot.gov

Signage upgrades include doubling up the intersection 

warning signs, adding cross street names, and yellow 

flags above the signs. Source: PennDOT.