Determination Of Headway And Average Travel Speed Of Vehicles
[Case study of post office-Kwara State Polytechnic permanent Site Car park Road]

Advantages of Traffic signals
Properly deigned traffic signals have the following uses:
(i)    They provide orderly movement of traffic and increase the traffic handling capacity of most of the intersections at grade.
(ii)    They reduce certain types of accidents, notably the right angled collisions.
(iii)    Pedestrians can cross the roads safely at the signalized intersection
(iv)    The signals allow crossing of the heavy traffic flow with safety.
(v)    When the signal system is properly co-ordinated, there is a reasonable speed along the major road traffic.
(vi)     Signals provide a chance to crossing traffic of minor road to cross the path of continuous flow of traffic stream at reasonable intervals of time.
(vii)     Automatic traffic signal may workout to be economical when compared to manual control.
(viii) The quality of traffic flow is improved by forming compact platoons of vehicles, provided all the vehicles move at approximately the same speed.
Disadvantage of Traffic Signals
(i)    The Rear-end collisions may increase
(ii)    Improper design and location of signals may lead to violations of the control system.
(iii)    Failure of the signal due to electric power failure or any other defect may cause confusion to the road users.
2.7    FACTOR THAT CONTRIBUTE TO JOURNEY TIME
Journey time is the time taken by the vehicle to travel between one points to another point in the highway.
Delay, congestion and accidents, contribute greatly to journey time. Apart from the problem of delay, Congestion and accident which contribute to journey time, there are other factors, which are primary cause of traffic free flow problem of study areas, they include
    Indiscriminate parking
    Street hawkers/ market traders
    Poor vehicle Condition
    Lack of road maintenance
   Disobedience to traffic regulations
Poor vehicle Condition: This among the factors that contribute to journey time. When the condition of a vehicle traversing  on a particular road is poor which may include; Engine condition, Bad tyres with worn out treads, Poor brakes and so on causes delay and extremely large hour of travel.
•    Power of vehicle: The power of the heaviest vehicles and their loaded weights govern the permissible and limiting values of gradient on roads. In this regard the total resistances to traction consisting of inertia, rolling resistance, air resistance and grade resistance are considered.
•    Speed of vehicle: The vehicle speed affects, (i) sight distance (ii) superelevation, length of transition curve and limiting radius on horizontal curves (iii) length of transition curves on vertical valley curves and on humps  (iv) width of pavement and shoulders on straight and on horizontal curves (v) design gradient (vi) capacity of traffic lane (vii) design and control measures on intersection.    
Indiscriminate parking:- Indiscriminate parking of vehicle as well as vehicle stalling in the middle at traffic stream.
Vehicle is being parked on street, which in turn cover part of the road. Hence traffic activities are distributed, which lead to poor level of service, comfort and convenience of free flow of the road ‘r to avoid bad sections at the road impedes the free flow,
Street hawker:- Hawking or selling along the street disrupts the effective performance of traffic. This is because in most cases half (½) of the road has been covered by market traders or hawkers, so the remaining portions of the road will not he enough to accommodate vehicles and other road users. As traffic try to avoid any damage to hawkers and the articles, this resulted into delay of traffic.
Lack of road maintenance:- Bad road, disrupted the effective performance of traffic free flow, in this attempt of the road user to avoid bad sections of the road impedes the free flow, hence traffic activities are disturbed which lead to poor level of service comfort I convenience of free flow.
Disobedience to traffic regulation:- This defines the mental characteristics of the road users i.e knowledge, skills intelligence and literacy can affect the road users characteristics. Knowledge of vehicle characteristics, traffic behavior, during practice, rules of roads and psychology of road users will be quite useful for safe traffic operations. Reactions to certain traffic situations become more spontaneous with experience. Understanding the traffic regulation and special instruction and timely action depends on intelligence and literacy.