i wanna do research about mesoscopic traffic flow parameters which affect crash severity in urban highway. i know that mesoscopic parameters are combination of macroscopic & microscopic parameters. but what kinds of variable should i consider for making a crash severity models
thanks for your time and consideration
Dear Sasan Zamani,
Following parameters may used in mesoscopic model:
1. LOS
2.Time
for other Mesoscopic Simulation Models pl visit this link.
http://ops.fhwa.dot.gov/trafficanalysistools/tat_vol1/sectapp_a.htm#a6
In mesoscopic models vehicles (or better packets of vehicles) are traced explicitly, while the performances of links are expressed in an aggregate way. Therefore, as for supply, you need the length, capacity and maximum density of each link of the network; as for demand, you need the flows (vehicles per time unit) at each node of the network. If you're interested in, I can send you a paper of mine about a mesoscopic model of Dynamic Network Loading.
Crash Severity on a urban highway, as on other roads, mainly depends on the kinetic energy. The kinetic energy by the speed. The speed by traffic flow, density, lane width, tortuosity of the route etc.
I would check the following parameters in function of the crash severity:
number and width of lanes, traffic flows per lane (in passenger car equivalents per hour), composition of traffic flow, speed (85th percentile or speed diagrams for the entire path), speed differences among different types of vehicles (such as cars, vans, trucks etc).
The interdependence of these parameters and the crash severity should give you some good results.
Good work and good luck
In my opinion and according to previous answers - speed is the main factor. But the severity also may be influenced by headway and spacing. Lower distance or shorter time for reaction of the driver = shorter time of breaking = higher level of the crash severity. And hope that we are discussing about crash between two or more vehicles.
I agree with the explanation of Dr. Mauro where you analyze platoons of vehicles . The relationship between crash severity and speed is directly proportional for the same class of vehicles
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