Intersection Proven 

Safety Countermeasure

Executive Summary:

Corridor Access Management

Managing access at the corridor level 

improves safety and business

Corridor Access Management (CAM) is a strategy 

that seeks an appropriate balance between the 

safety and mobility of a roadway facility with the 

access needs of adjacent land uses. CAM uses a combination of policies and strategies, such 

as closing, consolidating, or improving driveways, median openings, and intersections; adding or 

redesigning medians; and planned spacing of intersections, median openings, and driveways.

Addressing the concerns about Corridor Access Management improvements 

with data

Business owners along a corridor may fear that access management improvements will disrupt or 

otherwise negatively impact their businesses, but several studies over many years have dispelled 

this myth. Studies and surveys of property owners and businesses from North Carolina, Texas, Florida, 

Minnesota, Kansas, and Iowa, among others, reveal that access management projects do not 

result in adverse effects, and, in fact, can be beneficial. Importantly, a common factor in achieving 

this long-term success is early and frequent consultation between the road agency and corridor 

stakeholders, with special emphasis on the construction phase.

Studies conducted by State and local 

agencies, national organizations, and 

transportation trade associations consistently 

show that corridor access management 

can improve safety, mobility, accessibility, 

and even business along an entire stretch 

of roadway because it favorably impacts ALL 

properties along that corridor. 

http://safety.fhwa.dot.gov

Exhibit 1: Washington State Department of Transportation (WSDOT) conducted an analysis of the crashes in the corridor before and after 

the measures were in place. The results of the analysis showed that implementing access management practices significantly reduced 

accident severity and societal costs. (Source: WSDOT)
2

Offering a range of safety options 

Corridor access management techniques allow agencies to deploy flexible solutions for their unique 

environments. Common CAM techniques and their safety benefits include: 

• Relocation of Direct Left Turns. Restricting left-hand turns

reduces conflicts and improves safety along corridors.

• Provision of Turn Lanes. An undivided highway provides no

separation between opposing traffic, does not restrict turning

movements into and out of access points, and offers no

refuge for pedestrians.

• Median Type. The type of median determines the type of turning movements that can be

performed along a corridor and separates turning movements and opposing traffic.

Exhibit 2: Example of a method to relocate direct left turns. (Source: FHWA)

Restricting left-hand turns reduces 

conflicts and improves safety 

along corridors. The Highway 

Safety Manual summarizes results 

as follows: 

Total: 14 to 51 percent reduction

PDO: 5 to 11 percent reduction

Fatal/Injury: 31 to 36 percent 

reduction

Rear-end: 9 to 16 percent 

reduction

Right Angle: 33 to 36 percent 

reduction

Sideswipe: None reported

Exhibit 3: Example of exclusive turn lanes used to separate slower turning vehicles 

from through traffic. (Source: VHB)

Adding exclusive left-turn and 

right-turn lanes results in a 

reduction in total crashes (4 to 

44 percent) and fatal and injury 

crashes (6 to 55 percent) at rural 

and urban stop- and signalcontrolled intersections. 

Exhibit 4: These photos illustrate (left) undivided roadway; (center) two-way left-turn lane; (right) raised median. (Source: VHB)
3

• Signal Density. Signal density is defined as the number of signalized intersections per mile along

a given corridor. More signals create more access points, which add conflict points and increase

the potential for crashes and incidents involving pedestrians and bicyclists. 

• Unsignalized Access Density. Unsignalized access density is defined as the number of unsignalized

access points per mile along a given corridor, including driveways, unsignalized crossroads, and

median openings.

Improving operations for all stakeholders 

Reducing the frequency of access points, properly spacing 

access points, and managing turning movements increases 

capacity, reduces delay, allows more consistent travel speeds, 

and delivers better quality of service for all road users. 

Effects on Pedestrians and Cyclists

Studies show that a motorist failing to 

yield mid-block at a driveway or alley 

to a bicyclist accounted for between 

8.6 percent and 11.7 percent of all 

crashes involving a bicyclist and a 

motor vehicle. 

Exhibit 5: Example of closely spaced signals. (Source: VHB)

Increased signal density contributes to 

substantially higher crash rates. One 

study of corridor access management 

reports that total corridor crashes 

increase by 10 to 13 percent for each 

additional signal per mile depending on 

the adjacent land use.

Crash rates and crash severity 

increase as unsignalized access 

density increases. Studies show that 

each additional access point per 

mile increases the crash rate along 

a corridor by 3 to 5 percent.

Exhibit 6: Diagram illustrating conflict points associated with unsignalized accesses. 

(Source: FHWA)

Medians offer separation between opposing traffic, improve movements in and out of access 

points, and provide refuge for pedestrians.

• Converting a two-way left-turn lane (TWLTL) to a non-traversable median reduces total

crashes by 15 to 57 percent and reduces injury crashes by 33 to 48 percent. 

• Installing a TWLTL on an undivided roadway reduces crashes by 13 to 70 percent (Hallmark et

al. 2008). 

• Installing a non-traversable median on an undivided roadway reduces crashes by 21 to 53

percent. 

• Raised medians are associated with a 45 percent reduction in pedestrian crashes and 78

percent reduction in pedestrian fatalities. 

• A study of corridor access management by Gross et al. (in press) reports that the installation

of a non-traversable median reduces right-angle crashes along a corridor by 38 percent.
Overcoming potential challenges

Planning and implementing CAM improvements calls for careful policy making and pre-determined 

strategies, including: 

• Setting enabling policy

• Identifying funding

• Managing access during construction

• Building stakeholder support

• Demonstrating economic benefits

Using Visualization Tools

Visualization tools are used to enhance 

communication with multiple stakeholders by 

rendering a design, data, or other information 

in a visual format that can be easily 

understood. One such tool is the Corridor 

Visualization Explorer (CVE), which illustrates 

the effects of various access management 

strategies, can facilitate improvements 

planning and decision making, and aid in 

communicating with stakeholders. 

For complete information, including references, 

please refer to the Corridor Access Management 

Technical Summary.

FHWA-SA-15-006

LADOTD and the CVE Tool 

The Louisiana Department of Transportation and 

Development (LADOTD) sponsored a project to 

create a visualization prototype that can be 

used to improve how access management 

principles are conveyed to the public. 

Exhibit 7: The user selects road and traffic conditions in the top pane. 

These are visualized in the middle pane. The effects of these 

decisions can be seen on the dials in the bottom pane, which also 

includes a note to user. Dragging the cursor over the dials reveals 

explanations of the results. (Source: Teach America)

Highway 101 Corridor Access 

Management Case Study, 

Shakopee, Minnesota

Scott County and the City of Shakopee, 

Minnesota, completed a successful CAM 

project on a nine-block urban business 

corridor on Highway 101 with intersections at 

each block and 41 private property accesses. 

City and county staff were charged with 

making safety and mobility improvements for a 

nearly 25,000 vpd in an 80’ right-of-way. 

Officials decided on a five-lane undivided 

roadway with an “aggressive access 

management” process to remove redundant 

private access and encourage voluntary 

removal of private driveways. Nearly 50 

percent of the private accesses were 

eliminated.The project exceeded the 

expectations of the business community.

FOR MORE INFORMATION

Office of Safety: Jeffrey Shaw

jeffrey.shaw@dot.gov

Office of Operations: Neil Spiller

neil.spiller@dot.gov

FHWA Resource Center: Mark Doctor 

mark.doctor@dot.gov

FHWA Intersection Safety Web site: http://

safety.fhwa.dot.gov/intersection/