OBJECTIVE

The objective of this project is to develop and recommend a new MUTCD traffic signal warrant for a highway-highway intersection near a highway-rail grade crossing.

STATUS

The research results have been incorporated into the MUTCD.

BACKGROUND

At some stop-controlled intersections near highway-rail grade crossings, the distance from the stop line to the track is shorter than the length of a large vehicle. Insufficient sight distance may preclude waiting on the far side of the grade crossing before entering the intersection. A traffic signal that can be preempted by a train is a possible treatment but many of these intersections may not meet one of the traffic signal warrants in the Manual on Uniform Traffic Control Devices (MUTCD), Chapter 4C, "Traffic Control Signal Needs Study." These warrants set minimum thresholds for considering installation of a traffic signal and do not consider the proximity of heavy or light rail. A traffic signal may also be beneficial at other locations where vehicles often queue over the tracks.

It is desirable that the decision to install a signal at these types of locations be based on an assessment of risk. Factors that may influence the probabilities of risk include the number of trucks or busses approaching; the length and acceleration capability of those large vehicles; the space between the intersection and the tracks; the traffic volumes, speeds, and driver expectancy on the parallel highway; the acceptable gap or the time needed for a bus or truck to cross or turn onto the highway; and train characteristics such as the type of train (i.e., heavy or light), number of trains per day, and speeds. There may be other factors worth considering, such as sight distance, the type of railroad-crossing control in place, and the impacts on the train operator's and the transportation agency's liability.

TASKS (1.) Review relevant literature and ongoing efforts and briefly summarize the knowledge gained. (2.) Identify critical variables and engineering criteria that enter into the decision to install a traffic signal at these types of locations. (3.) Develop a risk assessment model that will form the basis for the warrant developed in Task 4. (4.) Develop a proposed traffic signal warrant and any needed supporting text for Chapter 4C of the MUTCD. (5.) Apply the proposed warrant to 20 case studies to illustrate the effects of including the warrant in the MUTCD. The data for these case studies (as defined in Task 2) will be supplied by Technical Committees of the National Committee on Uniform Traffic Control Devices (NCUTCD). (6.) Submit a final report documenting the entire research effort. Specific recommended text for the MUTCD shall be provided in an appendix to the report.