MPC
Research Projects (2007-08)

Identifying Number

MPC-291

Project Title

A New Generation of Emergency Escape Ramps, Year 1

University

Colorado State University

Project Investigators

John van de Lindt and Paul Heyliger

Description of Project Abstract

Runaway truck ramps are life-saving features of road systems that see a level of use that can vary widely with location. Some of these ramps, including those on high-use interstates, see very limited use. Others have events several times per month. In all cases, there are a number of design criteria that must be considered when constructing or modifying an optimal escape ramp in order to ensure driver safety whether it be the truck or collateral vehicles. Most designs are based on slowing down a vehicle with large mass while minimizing the chances of injury to the driver, damage to the vehicle, and potential for multi-vehicle accidents. At the same time, other considerations such as vehicle recovery, and cost related to the subsequent repair of the damaged (or used) escape ramp can also have impact. The proposed work focuses on new design concepts for runaway truck ramps. There has been very little work completed to date by either the transportation or academic community to develop alternative methods that may prove more effective in meeting the design criteria for these ramps. At the same time, such new approaches will be economically viable offering a solution that provides the optimal balance between performance and cost. In order to accomplish this, a performance-based design methodology will be incorporated with novel explorations of ramp systems that may be the next generation for this class of structure that will provide safer and more durable structures that are easier and less expensive to maintain. Performance-based design is a design paradigm that allows transportation agencies to target certain desired performance levels and cost is then subsequently minimized while the design maintains that specified performance level.

Project Objectives

The primary objective of this work is to consider and provide initial analysis and testing of an alternative class of emergency ramps barriers for the purpose of either modifying existing ramps or use in constructing new ramps in either low-use or rural regions.

Project Approach/Methods

The approach taken in this work can be separated into the following five basic tasks.

• Task 1 – Preliminary Calculations: Required Impulse
  Basic mechanics calculations will be performed to determine the impulsive forces necessary to slow a runaway vehicle on varying grade. These will be quantified in tabular form to give the necessary input for future calculations as other methods are explored to slow the vehicle. Since the vehicle weight will vary significantly with type of road, these parameters will be calculated for an array of both highway and rural road systems.
• Task 2 – Alternative Designs: Vertical Barriers and Sequential Webs
  Two of the most promising and simple methods that will be explored are what will be referred to as lawnmower-style networks of deformable beams and those containing fibrous networks. Both will be explored as alternatives on firm grade to determine the required material using both synthetic and biomass material candidates. The necessary stiffness and toughness capabilities will be used to determine the adequacy of these systems.
• Task 3 – Performance-Based Design of Prototype Systems
  The desired performance level will be achieved by applying performance-based design methods. Basic statistics derived from the previous tasks and runaway truck records (to the extent available) will be utilized to ensure that there is, for example, a W% chance (e.g. 99.9%) of a X lb truck stopping in Y ft if it enters the ramp at Z mph. The purpose of this task is to provide a consistent safety margin for all truck ramps throughout the states included within the MPC. This type of approach also will enable MPC entities to use different combinations of design variables and combinations thereof while maintaining the same ramp performance.
• Task 4 – Verification of Selected Designs via Prototype Testing
  Testing will be performed to verify the adequacy or alternative ramp designs. The key variable of interest is momentum; thus a momentum-based similitude approach will be applied to allow scale, e.g. 1/5 scale, testing. These scale prototypes of our design candidates will be constructed and tested at scale using a system of dynamic actuators on typical vehicle models to determine the true slowing/stopping capacity of the candidate ramp systems. The largest possible vehicle will be used based on the capabilities of these measurements.
• Task 5 – Reporting and Design Guidelines
  Reporting for this project will consist of the usual written and demonstration efforts as required by MPC.

Contributions/Potential Applications of Research

Most designs of runaway truck ramps have been somewhat ad hoc in that a lack of research and analysis of alternatives has led to adoption of known systems that will, for the most part, do the job of slowing down a vehicle with limited injury, damage, and cost. However, there are environments when alternatives should be explored both for the sake of improving existing ramps but also to consider the next generation of ramps that will provide cost and safety benefits to the citizens of MPC states.

The alternatives explored in this research will be based on the idea that cost-effective structural systems can be derived from either synthetic or "green" biomass sources that will yield inexpensive escape ramp designs that are both easy to maintain and provide a lower cost to the state. We propose that these systems be developed under the rubric of a performance-based design paradigm that will include accounting for a number of design considerations, including but not limited to:

• Life safety and health of driver
• Life safety of other drivers
• Damage to vehicle and contents
• Replacement cost of ramp
• Recovery cost and time
• Damage to surrounding landscape

By incorporating these considerations into the design process, a sequence of prototypical ramp models can be constructed and tested at scale and compared against predictive theoretical models of the same systems. Competing designs can then be examined to select candidates that may yield a better escape ramp.

Technology Transfer Activities

The results of this work will be made immediately available to state DOTs involved in the MPC and later to other state DOT's. It is envisioned that installation will be possible within 12 months of the culmination of the project.

A final report will be prepared under MPC auspices and a TLN teleconference will also be prepared and delivered upon project completion.

Time Duration

July 1, 2007 - June 30, 2008

Yearly and Total Project Cost

$85,000

TRB Keywords

Emergency, truck ramps, safety, rural regions, truck safety, trucks