Gorove Slade is Certified SWaM in Virginia
Gorove Slade is now a certified SWaM firm as a small business in Virginia. Gorove Slade offers comprehensive traffic engineering, transportation planning, and parking consulting services. We are experts in all modes of ground transportation including cars, trucks, public transportation, bicycles, and pedestrians. The firm serves both the private and public sectors.
“With our SWaM certification, we are better positioned to continue to provide our full range of transportation planning, traffic engineering and traffic signal design services on state-funded projects in Virginia.”
-Christopher Tacinelli, President
Gorove Slade holds a number of on-call Engineering and Planning projects throughout Virginia serving a wide range of public agencies. In addition, we serve as a subconsultant on a number of other on-call and project specific assignments to Engineering and Planning firms where we bring our specialization in Transportation Planning and Traffic Engineering to the project team. Our engineers and planners take a multimodal approach to projects, and we are experts on the functionality and interdependence of facilities that serve cars, pedestrians, bicyclists, and public transit. We are skilled in a full range of services related to forecasting, analysis and design and familiar with how to apply those services to local, state and federal processes.
Gorove Slade’s experience is brought to bear through a full-service and cost-effective team selected specifically for each project. Every project is assigned a Principal-in-Charge, a Project Manager, and technical and administrative support as needed. Working together in project teams allows Gorove Slade to provide responsive, comprehensive, professional service tailored specifically to the demands of each project.
On-Call Task Order Contracts
Gorove Slade serves as both the Prime firm and a Subconsultant on a number of on-call task order contracts throughout the Washington, DC metropolitan area. We have significant experience partnering with public agencies to help them evaluate needs, develop alternatives, determine funding requirements and produce full design plans to aid in construction. In addition, we have served on a number of design build teams where we have provided Traffic Signal Design Plans, Pavement Marking and Signage Plans and Maintenance of Traffic Plans.
Signal Design and Pavement Marking and Signing (PMS) and Maintenance of Traffic (MOT) Plan Preparation
Gorove Slade has experience working closely with state and local transportation agency staff in the initial phases of traffic signal project planning to identify all critical design elements. Also related to the design process, our firm is skilled in developing comprehensive signal timing plans for upload to the signal control cabinets and the agency control centers as part of the final installation process. We are skilled in all aspects of developing Maintenance of Traffic and Traffic Control Plans and have a number of staff that are work zone plan certified as well as Roadway Specialists.
Data Compilation and Forecasting
Utilizing the following five methodologies, Field Traffic Counts, Historical Data, Big Data, Extrapolation, and ITE Land Use Trip Generation, Gorove Slade forecasts traffic volumes for primary and secondary roadway links and intersections. In addition to more manual methods, Gorove Slade has experience leveraging information contained within long range models. In some instances we have had to supplement model runs with network or land use changes to develop alternative forecasts. For each project, all methodologies are evaluated and we move forward with the approach that is most applicable to the project scope and budget.
Multimodal Planning
Our particular transportation philosophy is well suited to help with multimodal transportation design services. We leverage practical experience to develop analyses and designs that blend traditional traffic engineering methodologies with modern thoughts on multi-modalism and non-auto-centric viewpoints. At Gorove Slade, the design of pedestrian and bicycle facilities identifies conflicts between modes and seeks to resolve those conflicts while still providing all necessary multimodal infrastructure. We are fluent in local, VDOT, and national standards, including those issued by AASHTO and NACTO.
Traffic Analysis and Modeling
PTV VISSIM is a state-of-the-art microsimulation software tool that analyzes multi-modal traffic flow. We are skilled in working with this tool to analyze freeway, surface street and urban transportation infrastructure analysis. Synchro® implements the methodologies of the industry-standard Highway Capacity Manual for various intersection traffic controls to determine operational levels of service and average vehicular delays. SimTraffic® models individual cars, trucks, buses and pedestrians traveling through a network of freeways, streets and multiple types of intersections. We rely heavily on these tools for almost every project.
Contact Us
Please contact our team if you are interested in discussing current or future projects where Gorove Slade could provide transportation planning and/or engineering services. We look forward to making your project successful and helping our partners meet their SWaM goals.
Tollbooth-style PUDO
Scramble-style PUDO
A scramble-style PUDO refers to when some (or all) students are being dropped off or picked up on the street, not an adjacent sidewalk, and walking between cars. For scrambles, some cars drive into a designated area, and then they all stop and don’t move again until all students arrive safely at the school or in their car at dismissal. Scrambles are often used during dismissal for schools with limited sidewalks since a scramble allows for more cars to load simultaneously.
Scramble-style PUDO
When helping plan a school, what does Gorove Slade recommend? In short, all of them. Our recommendation is to design a PUDO facility that can be flexible and work for several operational styles. Once up and running, the staff and teachers can try several and see what works best. The goal is to give them the tools they need to find the best solution.
An example is the new Cardinal Elementary School in Arlington, VA. We recommended a flexible system with ample sidewalks and a bypass lane, and once it was up and running, the facility operated a bit differently than planned. At dismissal, teachers split the facility in two, with two pick-up waiting spots – one for younger grades closer to the school and one for older ones further away. This allowed for quicker matching at dismissal times.
Afternoon pick-up at Cardinal Elementary School
PUDO Analysis
Gorove Slade handles the analysis of PUDO facilities in several ways. They are inherently tricky to analyze because some operational details are challenging to model, and the significant demand is very sensitive to variables leading to large ranges of results.
Here are three ways we approach analyzing PUDO:
Queuing Analysis/Equations
One method is to use classic queuing equations, which transportation engineers have used for decades for toll booths. They are based on three factors: the arrival rate of cars, the number of booths, and the processing speed of the toll. All three of these factors correspond to PUDO facilities.
Even so, queuing equations often fail to get accurate results for PUDO facilities. For example, we were working for a private school with a notorious PUDO problem at dismissal, so we went to the field and measured the arrival rate of cars, the number of vehicles that could load simultaneously, and the average time for each pick-up. We then entered that information into our queuing models, which then told us the queue should be negative, or in other words, there shouldn’t be a queue at all, as the car arrival rate was less than the overall number of cars that could be processed.
Subsequently, we returned to our observation notes and video. We realized the longest queue in the field was when dismissal began and that our model was correct in that the queue was being processed faster than additional cars arrived. Parents and guardians arrived so early that they stacked up well beyond the school property, but once dismissal started, the queue only got shorter as more cars showed up.
The lesson we learned here is that there are more factors in the queuing analysis than just the traditional three and that arrival rates are not random.
Comparable Analysis
A common transportation engineering practice is to study comparable locations, and sometimes, that works well for PUDO facilities, especially when queuing equations don’t work as described above. We’ve taken max queue data at several private and public schools. We can try to match the car length per student ratio from a site comparable to the one we’re working on, given the design and operational elements of their PUDO.
There are two issues with using comparable data. The first one is that there’s an extensive range of data, so using our observed data leads to a max queue range of 0.10 to 0.20 cars per student being picked up. The wide range is due to how well the PUDO processes traffic and the starting queue length. To use these ratios, you need to estimate how well the PUDO will operate within this range.
But more importantly, our observations found some schools with a max queue under the 0.10 cars per student range during dismissal. This wasn’t because they had fewer cars picking up students; it was because the cars weren’t all in the same place. For example, the school we observed once had around 25 to 30 cars picking up simultaneously, but only six were at the official pick-up spot at the front door. The others were in the parking lot or curbside in several locations. So, when planning PUDO facilities, the ability of parents to use informal locations near the school can be a huge factor in the max queues and overall PUDO operations.
VISSIM Modeling
When something other than engineering judgment combined with the two analyses stiles above is desired, we turn to detailed traffic models using the VISSIM software platform. VISSIM models are highly detailed and can account for things like starting queues and varying arrival rates. The main drawback is that they require more time and resources to assemble, and in the end, they still can’t arrive at a perfect representation of a PUDO since human behavior is always a factor.
Thoughtful design and operations can dramatically improve the pick-up and drop-off process. Whether planning a brand new PUDO experience or improving existing operations, the principles and methods discussed here provide a framework for tackling one of the most persistent logistical challenges for administrators and parents alike. By considering key factors like demand patterns, operational strategies, and facility types, schools can create systems that minimize queuing, reduce neighborhood impacts, and make the beginning and end of the school day better for all.
