Traffic conditions can change rapidly. A fallen tree orflooded bridge might force cars to detour onto adjacent streets. Lane closures during road work or special events can create bumper-to-bumper traffic. A crash may block lanes and require immediate response.
Pedestrian safety remains a persistent challenge in urban transportation systems. While improvements in vehicle technology and roadway design have contributed to the steady decline in vehicle fatalities, pedestrian-involved crash rates have increased by more than 80 percent since 2009.(1) Research has identified that these increases are most pronounced in urban areas, particularly on arterials, at non-intersections, and under low-light conditions.(2) These findings underscore the need to examine structural and contextual factors that shape pedestrian exposure, especially two interrelated concepts: walkability and social vulnerability.
The day that many transportation professionals were hoping for came on December 18, 2023, when FHWA published the 11th Edition of the Manual on Uniform Traffic Control Devices (MUTCD). This was the first new edition of the MUTCD since 2009, so people were clamoring to see what was in the new Manual that would reflect changes that have occurred in traffic control devices over the past 14 years. We had a glimpse of potential new items in the 2020 Notice of Proposed Amendments, but what was in the final rule?
Intelligent Transportation Systems (ITS) leverage technological advancements, information management, and systems engineering principles to optimize transportation facility operations. Within the ITS framework, Active Traffic and Demand Management (ATDM) strategies target real-time mitigation of traffic disruptions and bottlenecks, ultimately enhancing overall network performance. Managed Lanes (ML) represent a prominent ATDM strategy, offering dedicated lanes for vehicles meeting pre-defined criteria. Express lanes are a type of managed lanes designed to provide optional travel lanes for eligible vehicles.(1) Access is limited to these lanes, and the congestion is controlled through pricing strategies that can be static or dynamic during times of high demand.
A service interchange is a junction between a freeway and a non-freeway (called "arterial" in this paper) that uses ramps to connect the two roadways and a bridge to separate the through movements. They are important pieces of the transportation network: they cost a lot to build, they cause many impacts on the surrounding landscape, they are the sites of many crashes, users incur much delay at them, and they cost a lot to operate and maintain (with operations and maintenance often performed by local agencies). Projects to build new service interchanges or rebuild existing ones are constantly underway across the United States and elsewhere.
